blood and bleeding disorders

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BLOOD AND BLEEDING DISORDERS

UNDER THE GUIDANCE OF:

Dr. Binita SrivastavaDr. H.P. BhatiaDr. Archana AggarwalDr. Ashish K. SinghDr. Nidhi Gupta

PRESENTED BY:

Dr. Isha Jain

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Contents

Introduction Composition of blood Functions of blood Haemopoeisis

Erythropoiesis Granulopoiesis Agranulopoiesis Thrombopoiesis

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Contents RBC-

Normal count, Normal physiology Polycythemia, Anemia and its classification

WBC- Normal count, Classification Leucocytosis, Leucopenia, Leukemia

Platelets Mechanism of clotting, Clotting factors, Anticoagulants Anticoagulants, Bleeding disorders

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Contents

Blood groups and its clinical significance Erythroblastosis fetalis

Blood Transfusion Hazards of mismatched transfusion

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INTRODUCTION

Blood is a type of specialized connective tissue which serves as a transport medium for gases like oxygen and carbon-dioxide and waste products like urea, uric acid etc.

Interestingly, It is considered as a connective tissue in spite of it being a fluid.

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General characteristics

Total Blood volume : 5-6 litres(8% of

body weight or 80

mg/kg body weight

Specific gravity : 1050-1060

Viscosity : 4-5 times that of

water Blood pH : 7.4±0.05;alkaline

in nature

INTRODUCTION

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Composition of Blood

Blood constitutes of :-

Cells : Red blood corpuscles, White blood corpuscles and platelets constitute the essential cellular components of the blood.

Plasma : Plasma is a clear straw coloured fluid portion of the blood which represents 55% of the blood volume.

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Composition of Blood

Blood constitutes 55% of plasma and 45% of cellular components.

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Cells of Blood

The cellular elements of blood represents 45%of the total blood volume called Packed Cell Volume(PCV) or Haematocrit.

It includes : ERYTHROCYTES OR RED BLOOD CELLS(RBC’S) LEUCOCYTES OR WHITE BLOOD CELLS (WBC’S)

GRANULOCYTES

* NEUTROPHILS

* EOSINOPHILS

* BASOPHILS AGRANULOCYTES

* LYMPHOCYTES

* MONOCYTES PLATELETS OR THROMBOCYTES

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Scanning Electron Microscopic view of RBC,PLATELET AND WBC

WBC

PLATELET

RBC

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Plasma Plasma is a clear straw coloured fluid portion of the

blood which represents 55% of the blood volume.

It contains :-

91% water

9% solids which includes 1% inorganic molecules 8% organic molecules

Inorganic molecules majorly constitute Na ,Ca² ,Cl ,HCO₃ (mainly extra-cellular)⁺ ⁺ ⁻ ⁻ K ,Mg² ,Cu² ,PO₄³ (mainly intra-cellular)⁺ ⁺ ⁺ ⁻ Fe² ,Fe³⁺ ⁺

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Plasma

Of 8% organic molecules 7% are plasma proteins and 1% are other substances like Non protein

Nitrogenous (NPN)substances, sugars, fats, enzymes and hormones

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BLOOD

CELLS

RBC’S

WBC’S

PLATELETS

PLASMA

WATER

INORGANIC MOLECULES like

Na,Mg,Cu,Bicarbonate ions

Organic molecules like plasma proteins and NPN substances

sugars, fats etc.

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Functions of blood

Functions of blood

Respiratory Nutritive Excretory

‘Homeostatic’ for water,pH

and electrolyte concentratio

n

Regulation for body

temperature

Chemical for communicati

on and protection

Plasma protein

functions

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Respiratory:-Transport of oxygen from lungs to tissues and carbon-dioxide from the tissues to the lungs is carried out by blood.

Nutritive:- conveys absorbed food materials, glucose, amino acids, fatty acids, vitamins, electrolytes and trace metals from alimentary canal to the tissues for utilization and storage.

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Excretory:-Transports the metabolic wastes like urea, uric acid, creatinine etc. to the kidney, skin and intestines for the removal.

‘Homeostatic’ for water, pH and electrolyte concentration:-Blood forms internal environment of the cell i.e. ‘MILLIEU INTERIEUR’ in terms of volume, composition, concentration, pH and temperature, which is regulated to normal physiological limits with respect to minor changes in the body. This mechanism is called HOMEOSTASIS.

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Buffering power of hemoglobin helps to maintain constancy of blood pH.

Regulation of body temperature :-Blood(which has the major constituent as water) has –

High specific heat-buffers sudden change in body temperature.

High conductivity-which helps to take out heat from an organ for uniform distribution throughout the body.

High latent heat of evaporation.

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Chemical for communication and protection :- Concentration of hormones and various

substances is regulated through feed-back mechanism.

The entire complex of humoral antibodies important in defense against infection, initiation of inflammation and regulation of Haemostasis(clotting mechanism) is circulated in Blood.

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Plasma protein functions :- Exert the osmotic pressure which influences

the exchange of fluid between the blood and the tissues.

Act as a reservoir of proteins. Combine with many substances e.g. iron,

thyroxin and steroid hormones to form transportable complexes from which the active components are released at the appropriate sites

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Haemopoeisis

Haematopoiesis is a continuous, regulated process of blood cell production that includes cell renewal, proliferation, differentiation and maturation.

These processes result in the formation, development and specialization of all of the functional blood cells that are released from the bone marrow to the circulation

Ref.by: Hematology: clinical principles and applications: By Bernadette F. Rodak, George A. Fritsma, Kathryn Doig

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In adults, all these processes are primarily restricted to bone marrow.

During fetal development, this process occurs in different areas of developing foetus.

Haematopoiesis is divided into 3 phases :- Mesoblastic phase Hepatic phase Myeloid phase/ Medullary phase

Haematology: clinical principles and applications: By Bernadette F. Rodak, George A. Fritsma, Kathryn Doig

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Mesoblastic phase

Haematopoiesis begins around 19th day of embryonic development after fertilization in the yolk sac.

This phase is characterized by the development

of primitive erythroblasts, that produce good

amounts of hemoglobin and angioblasts(cells

that form future blood vessels).

It does not contribute to definite haemopoiesis

and occur intravascularly.

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Hepatic phase Hepatic phase of haemopoiesis begins around 4

to 5 gestational weeks and is characterized by recognizable clusters of developing erythroblasts, granulocytes and monocytes in addition with lymphoid cells.

The developing erythroblasts signal the beginning of definitive haemopoiesis with a decline in primitive haemopoiesis in the yolk sac.

This phase occurs extravascularly with liver being the major site.

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The developing spleen, thymus, kidney, lymph nodes also contribute to the hematopoietic process during this phase.

The formation of megakaryocytes also begin in this phase.


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Myeloid / Medullary phase

During the fifth month of fetal development, the haematopoiesis begins in the developing bone marrow cavity.

This phase is called The Medullary Phase because it occurs in the medulla or the inner part of the bone marrow.

Hematopoietic activity, specially myeloid activity is apparent during this phase of development.

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Myeloid /Medullary phase

Myeloid to Erythroid ratio approaches the adult level of 3:1 by the 21 weeks of gestation.

By the end of six months, the bone marrow is the primary site of haematopoiesis.


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SITES OF BLOOD FORMATION

Production of blood cells commences in the yolk sac of the embryo, but then shifts to liver, to a lesser extent to spleen, so that these organs become the dominant sites of production between the second and seventh month of gestation.

(contd.)

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The liver and spleen are then superseded by the bone marrow, which serves as the only important site of blood cell production after birth (an exception is lymphocyte production which occurs substantially in other organs in addition with bone marrow).

(contd.)

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Haemopoetic tissue fills all of the cavities within the bones of new born, but with increasing age becomes localized in cavities of:

Upper shafts of femur and humerus, The pelvis or the iliac bones, The sternum, and the vertebrae, The skull, The Ribs.

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Relative rates of red blood cell production in the bone marrow of different bones at different ages

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Types of Bone MarrowRed Bone Marrow

Haemopoetic tissue is known as red bone marrow due to its macroscopic appearance and it is present in the axial skeleton and the long bones.

From sixth month onwards the red bone marrow is the main organ of haemopoiesis, and from shortly before birth and for the rest of the life it is the only organ of red cell, granulocyte and platelet production.

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Red bone marrow

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If it is destroyed by disease, the spleen and liver may regain the ability to produce red cells – so called extra-medullary (ectopic) erythropoeisis.

Yellow bone marrow

The remaining bone marrow in the more peripheral regions of the skeleton contains predominantly fat, and is termed as Yellow bone marrow.

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Yellow bone marrow

It serves as a reserve space into which haemopoetic tissue can expand in response to an increased demand for blood cell production.

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Development of blood cells or Haemopoeisis

Stem cells/ Haemocytoblasts

The blood cells originate from Stem Cells in the bone marrow(referred to as Totipotential haemopoetic stem cells).

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Two types are identified mainly- pluri- and multipotential uncommitted stem cells. unipotential committed stem cells.

The pluripotential stem cells give origin to myeloid and lymphoid uncommitted stem cells.

These cells divide and some of them differentiate into committed unipotential stem cells.

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Pluripotential uncommitted

stem cells

Myeloid uncommitted

stem cells

Erythroblasts

Megakaryoblasts

Myeloblasts

Monoblasts

Lymphoid uncommitted

stem cellsLymphoblasts

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There are five different types of unipotential stem cells, namely

Erythroblasts, Myeloblasts, Lymphoblasts, Monoblasts and Megakaryoblasts.

These committed blast cells pass through a series of stages to form mature erythrocytes, granulocytes, lymphocytes, monocytes and megakaryocytes.

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Haemopoeisis

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Erythropoiesis

Red blood cells are produced by proliferation and differentiation of precursors whose dominant representatives in the bone marrow are erythroblasts.

Erythroblasts are referred to as normoblasts when their morphological features are within normal limits.

(contd.)

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Erythropoiesis

During the course of differentiation, the size of erythroblasts progressively decreases, and the character of nucleus and cytoplasm changes as the cells proceed toward the point where proliferative capacity is lost and hemoglobin becomes predominant protein in the cytoplasm.

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Erythroid series of Erythropoeisis

Stem cell /Progenitor cell

Proerythroblast

Basophil erythroblast

Polychromatic erythroblast

Orthochromatic erythroblast

Reticulocyte

Erythroblast

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The Erythroid seriesPro-erythroblast

It is the least mature of the morphologically identifiable members of the erythroid series.

It has a diameter of 14-18μm, and a basically round outline with minor peripheral protuberances. It has several nucleoli in the nucleus which is round and occupies most of the cell.

(contd.)

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Pro-erythroblast

Chromatin in the nucleus consists of a network of fine red purple strands.

Characteristic feature is that the peripheral cytoplasm is more basophilic than in the myeloblast (corresponding member of the granulocytic series).

Pro-erythroblasts undergo rapid division and give rise to Basophilic erythroblasts

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Basophilic erythroblast

This cell is round with a diameter of 10-15μm and more basophilic cytoplasm than pro-erythroblast.

It also undergoes rapid proliferation.

Its nucleus differs from that of pro-erythroblast by having coarser more basophilic chromatin strands.

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Polychromatic Erythroblast

It is a round cell between 7-10μm in diameter.

The characteristic polychromatic appearance of the cytoplasm is derived from the mixture of basophilic ribonucleic acid (RNA) and acidophilic hemoglobin.

Nuclear chromatin is in coarse, deeply basophilic clumps.

(contd.)

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Polychromatic Erythroblast

This cell occupies a position in the pathway of maturation between the early, immature stages characterized by active proliferation, and later stages characterized by absence of proliferation.

It has a predominance of hemoglobin in the cytoplasm of the cell. For this reason it is also frequently termed as Intermediary erythroblasts.

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Orthochromatic erythroblasts

It constitutes the next and final

stage of maturation of the nucleated red cell series.

They are smaller than their predecessors, and have a diameter of 7-10μm.

The nucleus is relatively small and pyknotic, with a homogenous blue-black appearance.

(contd.)

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Orthochromatic erythroblasts

Active hemoglobin synthesis occurs in the cytoplasm, which contains ribosomes and mitochondria.

Ribosomal RNA imparts a basophilic tint to the cytoplasm, although cytoplasm is predominantly acidophilic due to hemoglobin.

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Reticulocyte

The nucleus is extruded from the ortho-chromatic erythroblast to form reticulocyte.

Reticulocytes have the same biconcave discoid shape as mature red cells with similar staining characteristics of the cytoplasm which are distinguished from the mature red cells by a diffuse basophilic hue.

(contd.)

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Reticulocyte

They have a slightly greater volume and diameter than the mature red cells.

They loose their mitochondria and ribosomes over the course of few days, in doing so loose the basophilic tint and evolve into a mature erythrocyte

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Erythrocytes

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Erythrocytes

Erythrocytes normally enter the blood at the stage of the reticulocyte or mature erythrocyte.

It is currently not understood how these non-motile cells pass from extravascular space to blood within sinusoids of the bone marrow.

It remains within the vascular compartment during their life span of approximately 120days

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FATE OF RED BLOOD CELLS

Life span of RBC’s in blood stream is 120 days Senescent RBCs are phagocytosed and/or lysed

·Normally, lysis occurs extravascularly in the reticuloendothelial system subsequent to RBC phagocytosis (Kupffer cells).

· Lysis can also occur intravascularly (in blood stream)

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With aging, the metabolic systems of the red cells become progressively less active, and cells become more and more fragile, probably because their life processes wear out.

Once the cells become rigid and fragile, the cells rupture during passage through some tight spot of the circulation.

Many of the red cells self-destruct in the spleen, where they squeeze through the red-pulp of the spleen.

Here the spaces between the structural trabeculae of the red pulp, through which most of the cells must pass, are only 3μm wide, in comparison with 7.5μm diameter of red cells(so, the cells which are rigid can not pass through it).

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Spleen as a Sieve

Cross section of spleen

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When the cell membranes have ruptured, the released hemoglobin is phagocytosed by tissue macrophages throughout the body

Then this hemoglobin molecule splits into heme and globin.

The heme ring is opened to give free iron that is transported to the blood by transferrin or stored in liver as ferritin protein. a straight chain of four pyrrole nuclei that is substrate by which biliverdin is formed.

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Fate of RBC

MATURE RBC’S AFTER 120DAYS

RBC’S BECOME FRAGILE

THEIR CELL MEMBRANE RUPTURES

THESE CELLS ARE PHAGOCYTOSED AND LYSED BY TISSUE-MACROPHAGES(KUPFFER CELLS) IN THE RETICULO-

ENDOTHELIAL SYSTEM

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Kupffer cell phagocytosing fragile Red Blood Cell

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LYSIS OF RBC’S

HAEMOGLOBIN

SPLITS INTO

GLOBIN

HEME PIGMENT

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α and β CHAINS OF GLOBIN

ENTER THE AMINO ACID POOL

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HEME (IRON PROTOPORPHYRIN IX)

FERROUS IONS (Fe²⁺) STRAIGHT CHAIN OF 4 PYRROLE NUCLEI

Fe²⁺

Heme oxygenase

BILIVERDIN

FREE BILIRUBIN

Biliverdin reductase

Re-used for the synthesis of hemoglobin

FERRITIN (stored in liver)

Splits into

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FREE BILIRUBIN

MACROPHAGE BLOOD PLASMA

BINDS WITH

ALBUMIN

Free bilirubin combines strongly with plasma albumin and is transported in this combination throughout the blood and interstitial fluids.

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Within hours, the free bilirubin is absorbed through the hepatic cell membrane.

In passing to the insides of the hepatic cells, it is released from the plasma albumin and soon thereafter about 80% conjugated with glucuronic acid to form bilirubin glucuronide, and about 10% with sulfate to form bilirubin sulfate and the final 10% with a multitude of other substances.

In these forms, the bilirubin is excreted from the hepatocytes by an active transport process into the bile canaliculi and into the intestines as a part of bile.

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ALBUMIN

FREE BILIRUBIN

BLOOD PLASMA LIVER

CONJUGATED BILIRUBIN

BILE

Becomes a part of

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SMALL INTESTINES

CONJUGATED BILIRUBIN

UROBILINOGEN

By the bacterial action

BILE

LIVER

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Formation and fate of urobilinogen

Once in the intestines about half of the “conjugated” bilirubin is converted by bacterial action into the substance urobilinogen, which is highly soluble.

Some of the urobilinogen is reabsorbed through the internal mucosa back into the blood.

Most of this is once again re-excreted by the liver back into the gut, but about 5% is excreted by the kidneys into the urine.

(contd.)

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Formation and fate of urobilinogen

After exposure to air in the urine, the urobilinogen becomes oxidized to urobilin, or in the faeces, urobilinogen (now called stercobilinogen i.e. when in intestinal contents) becomes altered and oxidized to form stercobilin which further gets excreted in faeces.

(contd.)

Conjugated bilirubin Urobilinogen Urobilin

OXIDATION

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Normal serum Bilirubin Concentration

Serum Bilirubin

Total : 0.2 -0.8 mg/dl

Conjugated : 0.1 to 0.4 mg/dl

Unconjugated: 0.2 to 0.7 mg/dl

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HYPERBILIRUBINEMIA

· Increased plasma concentrations of bilirubin (> 3 mg/dL) occurs when there is an imbalance between its production and excretion · Recognized clinically as jaundice

Prehepatic (hemolytic) jaundice Results from excess production

of bilirubin (beyond the livers ability to conjugate it) following hemolysis

Excess RBC lysis is commonly the result of autoimmune disease; hemolytic disease of the newborn (Rh- or ABO- incompatibility); structurally abnormal RBCs (Sickle cell disease); or breakdown of extravasated blood

High plasma concentrations of unconjugated bilirubin (normal concentration ~0.5 mg/dL)

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Intrahepatic jaundice Impaired uptake,

conjugation, or secretion of bilirubin

Reflects a generalized liver (hepatocyte) dysfunction

In this case, hyperbilirubinemia is usually accompanied by other abnormalities in biochemical markers of liver function

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Post hepatic jaundice

Caused by an obstruction of the biliary tree

Plasma bilirubin is conjugated, and other biliary metabolites, such as bile acids accumulate in the plasma

Characterized by pale colored stools (absence of fecal bilirubin or urobilin), and dark urine (increased conjugated bilirubin)

In a complete obstruction, urobilin is absent from the urine

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Diagnosis of Jaundice

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Cell composition of aspirated normal adult bone marrow

Cell composition Percentage of total cells

Granulocyte series

Myeloblasts 0.1-3.5

Promyeloblasts 0.5-5.0

Myelocytes 5-23

Metamyelocytes 7-27

Band forms 9-18

Segmented forms 4-28

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Erythroid series

Pro-erythroblasts 0.1-1.1

Basophilic 0.4-2.4

Polychromatic 2-30

Orthochromatic 2-10

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Lymphocytes 5-24

Plasma cells 0-3.5

Monocytes 0-0.6

Macrophages 0-2

Megakaryocytes 0-0.5

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Granulopoiesis

Granulocyte are produced by the proliferation and maturation of pre-cursors from the earlier recognizable stage, the myeloblast.

Development of neutrophil, eosinophil and basophil series follows a similar pattern, except that the characteristic distinction between the colour of the granules becomes obvious at the myelocyte stage.

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Granulopoeisis

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Granulocyte series

Myeloblast

The myeloblast is a relatively large cell, 15-20μm in diameter, with a round to oval nucleus which occupies a large proportion of the cell.

There are no typical granules in the moderately basophilic cytoplasm.

(contd.)

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Myeloblast

Nuclear chromatin is arranged in a fine network of red-purple strands with occasionally small aggregates.

Nucleoli are typically prominent; while two or three is the usual number, there may be up to six nucleoli.

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Promyelocyte

The features of this cell are similar to those of the myeloblast, except for the development of some cytoplasmic granules and a slightly more coarse appearance of the chromatin.

Nucleoli are still present.

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Myelocyte

The myelocyte is the next stage in the maturation sequence.

It has prominent cytoplasmic granules, and the area of cytoplasm relative to the nucleus is greater than in the promyelocyte.

The cytoplasm is also less basophilic.

87

Nucleoli are no longer present, the chromatin appears more aggregated than in the promyelocyte.

Granulocyte precursors undergo active proliferation until after the myelocyte stage.

Subsequent steps involve the progressive changes in the conformation of the nucleus from round to segmented form in mature form.

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Metamyelocyte

The nucleus becomes indented and assumed a kidney shaped appearance in the Metamyelocyte.

Granules are prominent in the cytoplasm.

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Band or Stab-form stage

When the degree of indentation of the nucleus is greater than 50 percent of the nuclear diameter, the precursor has reached the band or stab-form stage.

Cytoplasmic granules are identical to those in the mature segmented form.

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Segmented or polymorphonuclear granulocytes

The terminal stage of development is a cell 12-14μm in diameter, characterized by a lobulated nucleus with two or five lobes of clumped chromatin, each linked by a thin chromatin strand.

Such segmentation of the nucleus gives rise to the designation of these cells as segmented or polymorphonuclear granulocytes.

(contd.)

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An abnormally high number of nuclear lobes is indicative of disordered granulopoeisis.

Approximately 1-3 percent of segmented neutrophils in females have clearly defined drum-stick appendages protuding from one of the nuclear lobes.(Davidson & Smith 1954).

(contd.)

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Drumsticks are not present in males, and are thought to reflect the presence of the condensed chromatin of the inactivated X-chromosome in female cells, equivalent to the Barr body in buccal mucosal cells.

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A Neutrophil band form (left) compared with a segmented Neutrophil (right).

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Polymorphonuclear eosinophils

Polymorphonuclear eosinophils are slightly larger than segmented and have a diameter of up to 16μm.

The number of nuclear lobes is usually two.

The cytoplasm has a pale hue similar to that of the segmented neutrophil, and contains many granules which are larger than segmented neutrophils.

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Polymorphonuclear Basophils

Polymorphonuclear Basophils are similar to the mature eosinophil, with the characteristic distinction that the granules are intensely basophilic, and tend to overlie and obscure the nucleus.

Stab and segmented granulocytes are motile, and thus possess capacity to migrate into the blood passing through bone marrow sinusoids.

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Agranulopoiesis

Formation of Monocytes and Macrophages

The monocyte-macrophage and granulocytic series collectively constitute the myeloid series, whose mature forms are the most important mobile phagocytic cells involved in host defense against infection.

97

Mature monocytes have less vigorous phagocytic capacity and a longer life span than segmented neutrophils.

They are able to re-enter the circulation, but are primarily distributed in the extra-vascular space.

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Monocyte-Macrophage series

Monoblast

Monoblasts are the least mature of the morphologically recognizable members of the monocyte-macrophage series, and are similar to appearance to the myeloblasts.

They are located in the bone marrow which is the major site of monocyte production.

99

Promonocyte

It is similar in size to the promyelocyte, but has a more irregularly shaped, and often deeply cleft, nucleus containing nucleoli.

The cytoplasm contains granules often arranged in a localized region which are larger and more basophilic than in mature monocyte.

100

Mature Monocyte

It is slightly larger than the segmented granulocyte.

It has irregularly shaped nucleus with a relatively fine chromatin pattern.

The shape of the nucleus ranges from almost round to sufficiently indented to produce a lobulated appearance.

101

Cytoplasm is abundant and of a gray blue tint which contains some small neutrophilic or basophilic granules, which are less common than in granulocytes.

Monocytes are motile cells and are thus capable of migrating into the blood passing through bone marrow sinusoids.

102

Macrophages

It range from 15-80 μm in diameter. They have one or more oval nuclei and an

irregular or oval cytoplasmic outline. Cytoplasm in larger macrophages is abundant

and contains granules and in some instances, vacuoles which may contain phagocytosed material.

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Lymphopoiesis

The production of lymphocytes exclusively take place from lymphoid uncommitted stem cells or progenitors.

Some are formed in the bone marrow, but more are formed in the spleen, lymph nodes and thymus from stem cells (lymphoblasts) which originally migrated from the bone marrow to these organs.

104

Germinal centres in other lymphoid tissues, such as lymph nodes and spleen, also actively produce lymphocytes but do so to a greater extent as a response to antigenic stimulation.

The life span of lymphocytes varies from days to years.

Radiation, Glucosteroid hormones can suppress lymphocytopoiesis and reduce its life span.

105

Lymphoid seriesLymphoblasts

They are slightly smaller than the myeloblasts which they resemble, except that the ratio of the diameter of the nucleus to that of the cell tends to be greater, and the number of nucleoli per nucleus tends to be fewer than in the myeloblast.

Lymphoblasts are actively dividing cells and there is no detectable difference in appearance between actively dividing lymphoid cells in normal germinal centers and small lymphocytes.

106

Differentiation into mature forms does not proceed along such morphologically well-demarcated steps as with other blood cells series and the feature reflect whether the cell is engaged in proliferative activity or is in the dormant state.

107

Large Lymphocyte

The large lymphocyte is in between 12 and 16 μm in diameter, and is round in outline.

The nucleus is round or slightly indented and its chromatin is more clumped than in the lymphoblast.

Cytoplasm is more abundant than in the lymphoblast and is usually pale blue, although it can extend to intense basophilia, particularly in inflammatory states.

Some granules may be present in the cytoplasm, but are fewer than in granulocytes

108

Small Lymphocytes

Small lymphocytes are between 9 and 12 μm in diameter, and are thus smaller than segmented granulocytes.

The cytoplasm usually forms only a thin, medium to a deeply basophilic rim encircling a round or marginally indented nucleus which contains deeply staining, heavily clumped chromatin.

109

Large and small lymphocyte in a smear

110

Plasma Cells

Plasma cells at the most immature stage of development resemble lymphoblasts, except for possessing more basophilic cytoplasm.

In the next stage of development, the nucleus is smaller and the chromatin is more clumped.

The nucleus at this intermediate stage has assumed the eccentric location at the periphery of the cell which is characteristic of mature plasma cell.

111

Plasma Cells

Nuclei of mature forms are round or oval with coarsely clumped chromatin.

The ratio of the diameter of the cell to that of the nucleus is large, and the cytoplasm is basophilic, in keeping with its large content of RNA laden ribosomes engaged in antibody synthesis.

112

Thrombopoiesis

Platelets are formed in the bone marrow by megakaryocytes, and are subsequently released into the vascular compartment where they play an essential role in haemostasis.

MEGAKARYOBLAST

113

Megakaryocytic seriesMegakaryoblast

The most immature stage of platelet development is the megakaryoblast, which resembles the myeloblast in its basic features.

These cells amount to less than eight percent of the total megakaryocyte population.

114

Promegakaryocyte

The promegakaryocyte is the next stage in the sequence of maturation, and is larger than its precursors because it has undergone endoreduplication.

Endoreduplication is nuclear replication without division of the cell, and is characteristic feature of the mature members of the megakaryocytic series.

(contd.)

115

Promegakaryocyte

Promegakaryocytes make up about 25 percent of megakaryocytes, and have deeply basophilic cytoplasm containing some basophilic granules.

The nucleus may be lobulated, and the chromatin is more deeply basophilic than in the megakaryoblast.

116

Megakaryocyte

Mature megakaryocytes range from 30 to 90μm in diameter, and contain 4-16 nuclear lobes with coarsely clumped chromatin.

The larger expanse of cytoplasm stains light blue and contains many small red-purple granules.

(contd.)

117

Platelets appear to be formed by protrusion into the bone marrow sinusoids

of the pseudopods of megakaryocyte cytoplasm, which detach into the bloodstream and fragment to yield small discoid platelets. (Bessis 1950).

118

Platelets

Platelets are small, anucleate, terminal stage of development of the megakaryocyte series.

They are discoid and have a diameter of 1-4 μm.

The cytoplasm stains light blue and contain small red purple granules which are centrally located in the platelets in blood films.

(contd.)

119

PLATELETS

Clumping, or aggregation of platelets, occurs readily, and is particularly prevalent in inadequately anticoagulated blood, where it can cause spurious lowering of platelet count.

120

Various blood cells entering the circulation after maturation

121

RBC(RED BLOOD CORPUSCLE)

122

Erythrocytes(RBC’S)

Hematocrit(Hct)(%) 47(males);42(females)

Normal Count 5.4million/μL(in men); 4.8 million/μL(in

women)

Hemoglobin(Hb)(g/dL) 13-18(males) ;

11.5- 16.5(females)

123

Mean corpuscular volume 87

(MCV)(fL)

Hematocrit × 10

RBC(10⁶/μL)

Mean corpuscular hemoglobin 29

(pg) = Hb × 10

RBC(10⁶/μL)

Mean corpuscular hemoglobin concentration(MCHC)(g/dL) 34 Hb × 100 Hct

124

Mean cell Diameter(MCD)(μm) 7.5 μm

RBC’s thickness 2μm(at edges),1μm(at

centre) Volume

82-99 μm³

Life span 120 days.

125

DIMENSIONS OF ERYTHROCYTE

126

RBC is a circular, biconcave, non-nucleated disc.

The biconcave shape renders the red cells quite flexible so that they can pass through capillaries whose minimum diameter is 3.5μm.

127

COMPOSITION 62.5% Water

35% Hemoglobin

2.5% :-

sugars(glucose),

lipids(lecithin, cholesterol),

proteins (glutathiones, albumin like insoluble protein),

enzymes of glycolytic system

vitamin derivatives, and

Ions – sodium ions, potassium ions, calcium ions etc.

128

Rouleaux (singular rouleau) are stacks of red blood cells (RBCs) which form because of the unique discoid shape of the cells in vertebrate body.

The flat surface of the discoid RBCs give them a large surface area to make contact and stick to each other; thus, forming a rouleau.

They occur when the plasma protein concentration is high, and because of them the ESR (erythrocyte sedimentation rate) is also increased. This is a non-specific indicator of the presence of disease.

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RED CELL CYTOSKELETON

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Spectroscopic view of RBC

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Structure of a Haemoglobin molecule

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AnemiaDefinition of Anemia

Anemia is present when the hemoglobin level in the blood is below the lower extreme of the normal range of age and sex of the individual.

The lower limit of normality is reduced during pregnancy.

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Classification of AnemiaPathophysiologic classification

I. Anemia due to increased blood loss

acute post-haemorrhagic anemia

chronic blood loss

II. Anemia due to impaired red cell production

a) Cytoplasmic maturation defects

Deficient haem synthesis like in iron deficiency anemia.

Deficient globin synthesis like in thalassaemia

b) Nuclear maturation defects- vitamin B12 and/or

folic acid deficiency; Megaloblastic anemia

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Classification of Anemia c) Defect in stem cell proliferation and differentiation

Aplastic Anemia, Pure red cell aplasia

d) Anemia of chronic disorders

e) Bone marrow infiltrations

f) Congenital anemia

III. Anemias due to increased red cell destruction (Haemolytic Anemias)

a)Extrinsic red cell abnormalities

b)Intrinsic red cell abnormalities

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Classification of AnemiaMorphologic classification

I. Microcytic hypochromic

II. Normocytic normochromic

III. Macrocytic normochromic

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Iron Deficiency Anemia

It is a type of microcytic, hypochromic anemia. It is the commonest nutritional deficiency throughout

the world but is more prevalent in developing countries.

It develops when supply of iron is inadequate for the requirement of hemoglobin synthesis(heme part)

The development of this deficiency depends on Increased blood loss Increased requirements Inadequate diet Decreased intestinal absorption.

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Etiology of Iron Deficiency Anemia Increased blood loss

Uterine e.g. excessive menstruation in reproductive years, repeated miscarriages, at the onset of menarche

gastrointestinal e.g. peptic ulcer, hemorrhoids, hookworm infestation, chronic aspirin ingestion

Renal tract e.g. hematuria, haemoglobinuria Nose e.g. repeated epistaxis Lungs e.g. haemoptysis

Increased requirements Spurts of growth in infancy, childhood Prematurity Pregnancy and lactation

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Etiology of Iron Deficiency Anemia Inadequate dietary intake

Poor socio-economic status Anorexia Elderly individuals due to poor dentition, apathy

and financial constraints Decreased absorption

Partial gastrectomy Achlorhydria Intestinal malabsorption such as in celiac disease

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Clinical features It is much more common in women between the age

of 20 to 45 years than in men, in the active growth of infancy, childhood and adolescence.

The onset is usually slow. The usual symptoms are of weakness, fatigue,

dyspnoea on exertion, palpitations and pallor of the skin, mucous membranes and sclerae.

Older patients may develop angina and congestive cardiac failure.

Long-standing chronic iron deficiency causes epithelial changes like spoon-shaped nails(koilonychia), atrophic glossitis, angular cheilitis, and esophagus dysphagia(Plummer-Vinson syndrome)

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Iron deficiency anemia

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Iron deficiency anemia

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Esophageal web in Plummer Vinson syndrome

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Blood picture and red cell indices

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Prussian Blue Stain of Bone Marrow

IRON PRESENT NO IRON PRESENT

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Blood picture and red cell indices Haemoglobin

Fall in haemoglobin is an essential feature. Red cells

Microcytic and hypochromic Hypochromia generally precedes microcytosis Central pallor in red cells due to decreased

hemoglobin content. Target cells, elliptical forms and polychromatic

cells are often present. Reticulocyte count

It can be normal or reduced.

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Target cells and Elliptical cells.

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Blood picture and red cell indices Absolute values

Red cell indices reveal a diminished MCV(below 50fl), diminished MCH(below 15pg) and diminished MCHC(below 20g/dl)

Leucocytes and platelet count The total and differential leukocyte count is usually

normal and platelet count is also normal but can be raised in case of recent bleeding.

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Treatment of Iron Deficiency Anemia Correction of the etiology

Appropriate surgical, medical or preventive measures are instituted to correct the cause of blood loss.

Oral therapy Iron deficiency responds very effectively to the

administration of oral iron salts such as ferrous sulfate. One tablet containing 60 mg of elemental iron is administered thrice daily.

Parenteral therapy It is indicated in cases who are intolerant to oral iron

therapy, in GIT disorders such as malabsorption, or a rapid replenishment of iron stores is desired such as in women with severe anemia.

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The megaloblastic anemias are disorders caused by impaired DNA synthesis.

In this anemia, the maturation of the nucleus is delayed relative to that of the cytoplasm.

Since cell division is slow, but the cytoplasmic development progresses normally, the nucleated red cell pre-cursors tend to be larger which Ehlrich in 1880 termed as megaloblasts.

The most prominent abnormality in this disorder is Macrocytosis.

Defective DNA synthesis may be due to vitamin B12 and/or folic acid deficiency.

Megaloblastic anemia

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Etiologic Classification

Vitamin B12 deficiency Inadequate dietary intake e.g. strict vegetarians,

breast-fed infants Malabsorption* Gastric causes : pernicious anemia, gastrectomy,

congenital lack of intrinsic factor

* Intestinal causes : tropical sprue, ileal resection, Crohn’s disease

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Etiologic Classification Folate deficiency

Inadequate dietary intake e.g. in alcoholics, teenagers, poverty, old age

Malabsorption e.g. in tropical sprue, Crohn’s disease

Excess demand Physiological : pregnancy, lactation, infancy Pathological : malignancy, increased

haemopoiesis, tuberculosis Excess urinary folate loss e.g.in active liver

disease, congestive heart failure

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Etiologic Classification Other causes

Impaired metabolism e.g. inhibitors of dihydrofolate (DHF) reductase such as methotrexate and pyrimethamine, alcohol, congenital enzyme deficiencies.

Unknown etiology e.g. in Di Guglielmo’s syndrome, congenital dyserythropoeitic anemia

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Pernicious anemia

Pernicious anemia is a relatively common chronic disease.

Also known as Addison’s Anemia and Biermer’s anemia.

Its history was culminated in the discovery by Whipple, and Murphy and Minot of the value of liver therapy.

Although the exact nature of the disease is still unknown, but it is generally recognized as being due to atrophy of gastric mucosa resulting in failure to secrete still ‘unidentified’ intrinsic factor.

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Clinical features

Pernicious anemia is rare before the age of 30 years and increases in frequency with advancing age.In the United States, males are affected more commonly than females but in Indian sub-continental regions, females are more affected than males.

Rarely it can be seen in children under 10 years of age (juvenile pernicious anemia).

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Clinical features Hematologic abnormalities Symptoms of anemia like weakness, fatigue,

exertional dyspnea, palpitations, dizziness and aches and pains all over the body are commonly present.

Hyperpigmentation over dorsum of the hands, or knuckles may also be seen.

There may be mild hepato-splenomegaly.

Shah A. Megaloblastic anemia - Part II. Indian J Med Sci 2004;58:309-11

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Clinical features Neurologic abnormalities Neurological abnormalities occur only with B12

deficiency.

Patients commonly present with paresthesias characteristic of peripheral neuropathy.

B12 deficiency can also cause degeneration of the posterior and lateral columns of the spinal cord with features ranging from unsteadiness and inco-ordination of gait to ataxia and spastic paraplegia.

B12 deficiency in infancy is associated with mental retardation.


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Clinical features Neurologic abnormalities (contd.)

Folate deficiency during pregnancy is known to be associated with congenital anomalies, most notably neural tube defects.

Folate deficiency can also lead to elevated homocysteine levels which is a major risk factor for atherosclerosis and venous thrombosis.


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Oral manifestations

Glossitis, glossodynia and glossopyrosis are some characteristic features of this disorder, i.e. there is gradual atrophy of the papillae of the tongue leading to smooth, bald tongue – Moeller’s glossitis or Hunter’s glossitis.Loss of taste sensation have also been reported.

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LABORATORY FINDINGS

Red blood counts are seriously decreased, often to 1 million/cubic millimeters or less.

Macrocytosis is the characteristic feature with poikilocytosis.

Hemoglobin level is increased. Pernicious anaemia is identified with a high MCV

and a normal MCHC (that is, it is a macrocytic, normochromic anemia). Ovalocytes are also typically seen on the blood smear, and a pathognomonic feature of megaloblastic anemias (which include pernicious anemia and others) is hypersegmented neutrophils.

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Pernicious anemia (giant band)

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Pernicious anemia (Howell jolly bodies)

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Pernicious anemia (macro- ovalocytes)

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Diagnosis of Pernicious anemia

Schilling test

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Treatment of Pernicious Anemia

Patients of Pernicious Anemia are treated with Vitamin B12 in the following way : Replacement therapy with vitamin B12. Symptomatic and supportive therapy such as

physiotherapy for neurologic deficits, and blood transfusion.

Follow-up for early detection of cancer of the stomach. Most of the abnormalities due to vitamin B12 deficiency

can be corrected except the irreversible damage to the spinal cord. Corticosteroid therapy can improve the gastric lesion.

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Thalassemia

Thalassemia is a group of inherited disorders of hemoglobin synthesis characterized by a reduced or absent output of one or more of the globin chains of adult hemoglobin .

The name is derived from the Greek words Thalasso = Sea" and "Hemia = Blood" in reference to anemia of the sea.

Thalassemia result from over 150 mutations of the globin genes that result in the absence or a reduction of the globin chains(α or β)

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Alpha ( ) thalassemia

It appears when a person does not produce enough alpha chains for hemoglobin. It is mainly prevalent in the Africa, the Middle East , India, and occasionally in Mediterranean region countries. There are four types categorized according to the severity of their effects on persons with thalassemia :-

Silent Carrier State (1 affected gene) Alpha Thalassemia Trait (2 affected genes) Hemoglobin H Disease (3 affected genes) Alpha Thalassemia Major (also called hydrops fetalis, 4

affected genes)

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It appears when a person does not produce enough beta chains for hemoglobin.

It is mainly prevalent in the Mediterranean region countries, such as Greece, Cyprus, Italy, Palestine and Lebanon.

There are 3 types categorized according to severity: Thalassemia minor Thalassemia intermedia Thalassemia major

Beta (ß) thalassemia

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Chromosomes

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An example of inheritance:a carrier married to a normal person

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An example of inheritance- Cont:marriage between two carriers

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Types of α thalassemia Silent Carrier State (1 affected gene)

The silent carrier will have normal hemoglobin levels and red cell indices but can pass on the affected gene to their offspring. Often, these individuals are identified only after having a child with Hb H disease or alpha thalassemia trait.

Alpha Thalassemia Trait (2 affected genes)

Patients who have alpha thalassemia trait have red blood cells that are microcytic, hypochromic, have decreased MCV, and have a mild chronic anemia, but they do not generally experience any other symptoms. This is an anemia that does not respond to iron supplements.

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Types of α thalassemia Hemoglobin H Disease (3 affected genes)

With this condition, the decrease in the amount of alpha globin chains produced causes an excess of beta chains, which then aggregate into beta tetramers (groups of 4 beta chains), known as Hemoglobin H.

Hb H disease can cause moderate to severe anemia and splenomegaly (enlarged spleen).

Some individuals are asymptomatic while others have severe anemia. Hemoglobin H disease is found most often in individuals of Southeast Asian or Mediterranean descent.

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Types of α thalassemia

Alpha Thalassemia Major (also called hydrops fetalis, 4 affected genes)

This is the most severe form of alpha thalassemia. In this condition, no alpha globin is produced, therefore, no Hb A or Hb F are produced.

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Types of α thalassemia

Foetuses affected by alpha thalassemia major become anaemic early in pregnancy.

They become hydropic and frequently have enlarged hearts and livers (swollen abdomen).

This diagnosis is frequently made in the last months of pregnancy when a fetal ultrasound indicates a hydropic foetus.

About 80% of the time, the mother will have toxaemia and can develop severe postpartum bleeding (haemorrhage).

Foetuses with alpha thalassemia major are usually miscarried, stillborn, or die shortly after birth.

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Types of β thalassemia

Thalassemia Minor (Trait)

This can also be called (carrier state), meaning that the person carries the genetic trait for thalassemia.

Such people usually practice normal life, but may suffer from a mild form of anemia.

Thalassemia Intermedia

Caused by the reduced availability of beta chains in hemoglobin and can lead to moderate to severe anemia and an array of complications including bone deformities and splenomegaly.

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Types of β thalassemia

Thalassemia Major (Cooley's Anemia) Caused by the unavailability of beta chains in

hemoglobin leading to a very severe and fatal if left untreated anemia.

It requires regular blood transfusions leading to iron-overload which is treated with chelation therapy to prevent death from organ failure.

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Signs and symptoms

Thalassemia carriers (trait) Usually no signs or symptoms are apparent, except for a

mild anemia. Carriers are usually initially detected through screening, or

when performing routine CBC (complete blood count). Later it can be confirmed using hemoglobin electrophoresis.

Thalassemia major

Signs such as paleness and growth retardation, are readily detectable since the first year of life. Those are mainly due to severe anemia. The child has a yellowish pallor of the skin and the oral mucosa.

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Signs and symptomsChild also exhibits chills, malaise and generalised weakness. Later bone deformities and hepato-splenomegaly develops which leads to protrusion of the abdomen.The face often develops mongoloid features due to slanting of eyes, prominence of cheek bones, protrusion of maxillary anterior teeth, and the depression of the nose.

Roentgenographic features The skeletal changes in this disease are most striking.

In skull there is thickening of the diploe, the inner and outer plates become poorly defined, trabeculae between the plates become elongated producing a hair-on end appearance on the surface of the skull.

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Roentgenographic features(contd.)

Both the skull and long bones exhibit some degree of osteoporosis. The bony changes occur early in life and tend to persist, particularly those in the skull.

Intra oral roentgenograms in some cases reveal a very peculiar trabecular pattern of the maxilla and mandible, characterized by an apparent coarsening of some trabeculae and the blurring and disappearance of others, resulting in a ‘salt and pepper’ effect.

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Clinical features of thalassemia

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Cooley’s anemia

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Laboratory diagnosis

Thalassemia minor: Blood smear shows hypochromia and

microcytosis (similar to Iron Deficiency Anemia). Blood indices: MCV< 75 fl, Hb usually> 10,

Hematocrit> 30% Thalassemia major:

Blood smear shows profound microcytic anemia, with extreme hypochromia, tear drop, target cells and nucleated RBCs exhibiting a poikilocytosis,

and anisocytosis. Hemoglobin may be very low at 3-4 g/dl.

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Blood picture of a ß thalassemia major patient

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Management and treatment

Thalassemia minor (trait) :

No need for any treatment, since the carriers are usually symptomless.

Thalassemia major:

The severe life-threatening anemia, requires regular life long blood transfusion, to compensate for damaged red blood cells.

The continuous blood transfusion will eventually lead to iron overload, which must be treated with chelation therapy to avoid organ failure.

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Management and treatment

Other novel treatments like bone-marrow transplantation are very costly.

New treatments includes the use of oral chelators, to replace the chelation treatment using Desferal delivered by infusion under the skin through a battery-operated pump.

Gene therapy is also an option still researched

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APLASTIC ANEMIA

Aplastic anemia is a severe, life threatening syndrome in which production of erythrocytes, WBCs, and platelets has failed.

Aplastic anemia may occur in all age groups and both genders.

The disease is characterized by peripheral pancytopenia and accompanied by a hypocellular bone marrow.

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HYPOCELLULAR BONE MARROW IN APLASTIC ANEMIA

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APLASTIC ANEMIA

Etiology Acquired

Most cases of aplastic anemia are idiopathic and there is no history of exposure to substances known to be causative agents of the disease

Exposure to ionizing radiation – hematopoietic cells are especially susceptible to ionizing radiation. Whole body radiation of 300-500 rads can completely wipe out the bone marrow. With sublethal doses, the bone marrow eventually recovers.

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APLASTIC ANEMIA

Etiology Acquired

Most cases of aplastic anemia are idiopathic and there is no history of exposure to substances known to be causative agents of the disease

Exposure to ionizing radiation – hematopoietic cells are especially susceptible to ionizing radiation. Whole body radiation of 300-500 rads can completely wipe out the bone marrow. With sublethal doses, the bone marrow eventually recovers.

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Chemical agents – include chemical agents with a benzene ring, chemotherapeutic agents, and certain insecticides.

Idiosyncratic reactions to some commonly used drugs such as chloramphenicol or quinacrine. Infections – viral and bacterial infections such as infectious mononucleosis, infectious hepatitis, cytomegalovirus infections, and miliary tuberculosis occasionally lead to aplastic anemia

Pregnancy (rare)

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APLASTIC ANEMIA

Paroxysmal nocturnal hemoglobinuria – this is a stem cell disease in which the membranes of RBCs, WBCs and platelets have an abnormality making them susceptible to complement mediated lysis.

Other diseases – preleukemia and carcinoma

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APLASTIC ANEMIA

Congenital disorders Fanconi’s anemia – the disorder usually becomes

symptomatic ~ 5 years of age and is associated with progressive bone marrow hypoplasia. Congenital defects such as skin hyperpigmentation and small stature are also seen in affected individuals.

Familial aplastic anemia – a subset of Fanconi’s anemia in which the congenital defects are absent.

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Clinical manifestations Fatigue Heart palpitations Pallor Infections Petechiae Mucosal bleeding

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APLASTIC ANEMIA

Lab findings Severe pancytopenia with relative lymphocytosis

(lymphocytes live a long time) Normochromic, normocytic RBCs (may be slightly

macrocytic) Mild to moderate anisocytosis and poikilocytosis Decreased reticulocyte count Hypocellular bone marrow with > 70% yellow marrow

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SICKLE CELL ANEMIA Sickle cell anemia is a hereditary type of chronic

hemolytic anemia transmitted as a mendelian dominant, nonsex-linked characteristic, which occurs almost exclusively in blacks.

The name is derived from the peculiar microscopic appearance of sickle or crescent shaped erythrocytes found in circulating blood.

Normal adult hemoglobin(Hb A) is genetically altered to produce sickle hemoglobin(Hb S) by the substitution of valine for glutamine at the sixth position of β globin chain.

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Spectroscopic view of RBC in Sickle cell anemia

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Sickle cell anemia Clinical features Sickle cell anemia is more common in females and

usually manifests before 30 years of age. Patients manifest a variety of features related to the

anemia per se. Thus the patient is weak and short of breath and

easily fatigued. Pain in the joints, limbs and abdomen, as well as

nausea and vomiting, is common. Systolic murmur and cardiomegaly also occur. One characteristic feature is packing of red blood

cells in peripheral vessels with erythrostasis and subsequent local tissue anoxia.

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Sickle cell anemia

Oral manifestations

Mild to severe generalized osteoporosis and a loss of trabeculation of the jaw bones with the appearance of large, irregular marrow spaces.

The trabecular change is prominent in the alveolar bone.

There are no alterations in lamina dura or periodontal ligament.

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Sickle cell anemia

Roentgenographic features

Roentgenograms of skull exhibit hair on end pattern identical to thalassemia, congenital hemolytic jaundice, and sometimes, in chronic iron deficiency anemia.

The outer table of bone may appear absent and the diploe thickened.

Generalized osteoporosis may be present. The long bones of children may exhibit enlarged

medullary cavities with thin cortices, while in adults they become sclerotic with cortical thickening due to fibrosis of the marrow.

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Sickle cell anemia Laboratory diagnosis The red blood cell count may reach a level of

1,000,000 cells or less per cubic millimeter with a decreased hemoglobin level.

On blood smear, sickle shaped red blood cells are commonly seen.

The sickle hemoglobin molecule undergoes gelation or crystallization when it is deoxygenated, and this physically distorts the erythrocyte producing the sickle shape.

These distorted cells then “logjam” and produce stasis within the microvasculature.

Damage to erythrocytes occurs in sickled cells and leads to fragmentation and intravascular hemolysis.

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Sickle cell anemia

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Sickle cell anemia Treatment

There is no specific treatment for this disease except transfusion during a crisis.

The prognosis is unpredictable. The four main treatment options are:

Blood Transfusions Drug Treatment like with hydroxyurea. Blood and Marrow Stem Cell Transplantation Gene Therapy

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Polycythemia vera is a chronic disease with an insidious onset characterised by an absolute increase in the number of circulating red blood cells and in the total blood volume.

It is of unknown etiology, but is considered as a familial disease by some haematologists.

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Clinical features Polycythemia vera often manifests itself primarily by

headache or dizziness, weakness and lassitude, tinnitus, visual disturbances, mental confusion, slurring of speech and inability to concentrate.

The skin is flushed or diffusely reddened as a result of capillary engorgement which is most obvious on head, neck and extremities.

Splenomegaly, sometimes associated with pain, is a constant feature.

Gastric complaints such as belching and peptic ulcers are common.

The disease is more in males and usually occurs in middle age or later.

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Clinical features

Flushing of the skin of the face

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Oral manifestations

The oral mucosa appear deep purplish red, gingiva and tongue being most prominently affected.

The gingivae are often engorged and swollen and bleed upon the slightest provocation.

Submucosal petechiae, ecchymoses and hematomas are also common.

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Laboratory findings

The red blood cell count is elevated and may even exceed 10 million cells per cubic millimetres.

The hemoglobin content of the blood is also increased, often as high as 20 gm/dl, although the colour index is low.

Because of the great number of cells are present, both the specific gravity and viscosity are increased.

Increase in the number of leukocytes and platelets is also seen.

There is usually hyperplasia of all elements of the bone marrow.

Bleeding and clotting times are normal.

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Treatment

No specific treatment for polycythemia is known, although several methods may be used to relieve the symptoms.

The patient may be periodically bled, or substances may be administered to destroy blood( phenylhydrazine) or to interfere with its formation( nitrogen mustard or even X ray radiation).

In recent years, radioactive phosphorus ( P³² has been used.

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WBC(WHITE BLOOD CORPUSCLES)

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WHITE BLOOD CELLS(LEUKOCYTES) Leukocytes: have nuclei and other organelles, not

involved in oxygen transport. Functions:

Defend against pathogens

Remove toxins and wastes

Attack abnormal cells WBC in blood vs. tissue

Very small numbers in blood : 6000 to 9000 per microliter

Outnumbered 1000:1 by RBCs

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Only 1% of WBC are in blood Most WBCs are not found in blood but instead in

connective tissue proper and in lymphatic system organs.

Circulating WBCs WBCs can migrate out of bloodstream into tissues Have amoeboid movement (using actin) Attracted to chemical stimuli (positive chemotaxis) Some are phagocytic: neutrophils, eosinophils and

monocytes.

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Neutrophils

Also called polymorphonuclear leukocytes 50–70% of circulating WBCs; 3,000 – 6,000/cumm. Pale cytoplasm granules with lysosomal

enzymes and bactericides (hydrogen peroxide superoxide)

Phagocytes that are the first to attack bacteria, engulf and digest pathogens with defensins

Release prostaglandins and leukotrienes

(inflammation and alarm call) Form pus

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NEUTROPHIL(WBC)

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Eosinophils

Also called acidophils 1–4% of circulating WBCs;150-300/cumm. Acidophilic cytoplasm, pink in colour Attack large parasites by excreting toxic

compounds Sensitive to allergens Control inflammation with enzymes that

counteract inflammatory effects of

neutrophils and mast cells

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EOSINOPHIL(WBC)

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Basophils

Less than 1% of circulating WBCs;10-100/cumm. Slightly basophilic cytoplasm, appears blue Plenty of granules are present which obscure the

nucleus boundary. Small cells that accumulate in damaged tissue Release histamine to dilate blood vessel and

heparin prevent blood clotting Similar to mast cells (found in the tissues)

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BASOPHIL(WBC)

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Monocytes

2–8% of circulating WBCs, 300-600/cumm Largest WBC, irregular in shape Pale staining, single, kidney shaped nucleus which

is eccentric in position Enter peripheral tissues and become macrophages Engulf large particles and pathogens Secrete substances that attract immune system cells

and fibroblasts to injured area

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MONOCYTE(WBC)

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Lymphocytes

T cells, B cells and NK cells 20–40% of circulating WBCs;1500-2700/cumm Note the small amount of cytoplasm Small, just slightly larger than RBCs Migrate in and out of blood Most of them are in connective tissues and

lymphatic organs (spleen, lymph nodes) Respond to specific antigens

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LYMPHOCYTE(WBC)

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Agranulocytosis

Agranulocytosis is a serious disease involving leukocytes( also known as Granulocytopenia).

It is often classified as primary(in which etiology is unknown) and secondary(etiology recognized).

The most common known cause of secondary agranulocytosis is ingestion of any of a considerable variety of drugs (even in very small amounts).

Those compounds can be responsible for idiosyncratic reactions manifested in the form of urticaria, cutaneous rashes and edema.

But in case of some drugs it occurs only after continued administration.

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The following drugs are those which have been reported to produce agranulocytosis :-

Amidopyrine Barbiturates Chloramphenicol Gold salts Phenacetin Phenothiazines Phenylbutazone Quinine Sulfonamides

Thioglycolic acid Thiouracil Tolbutamide

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Clinical features

Agranulocytosis can occur at any age but is more common in adults, particularly in women.

The disease frequently affects health professionals (e.g., physicians, dentists, nurses, pharmacists) probably because they have easy access to the offending drugs and often use drug samples injudiciously.

The disease commences with a high fever accompanied by chills and sore throat with malaise and weakness.

The most characteristic feature is presence of the infection specially in the oral cavity or GIT.

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Oral manifestations

The lesions appear on oral mucosa, tonsils, pharynx with gingiva and palate are particularly involved.

The lesions appear as ragged necrotic ulcers covered by gray or even black membrane.

There is no apparent inflammatory cell infiltration around the periphery of the lesion.

It is obvious that all oral surgical procedures, particularly tooth extraction are contraindicated in agranulocytosis.

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Histologic features

The pathognomonic feature of this disease is that the ulcerated areas exhibit no polymorphonuclear reaction to the bacteria in the tissues, and rampant necrosis ensues.

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Laboratory findings

The WBC count is often below 2000 cells per cubic millimeter with almost complete absence of granulocytes or polymorphonuclear cells.

The red blood cell count and platelet count is usually normal, although occasionally anemia is present.

The bone marrow is relatively normal except for the absence of granulocytes, metamyelocytes and myelocytes.

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Treatment and prognosis

The treatment of agranulocytosis is not specific, but should consist principally in recognition and withdrawal of the causative drug and in administration of the antibiotic drugs to control the infection.

Although it is a serious disease but prognosis is good if responsible agent is discovered.

Death is usually related to massive infection, and thus the disease carried a high mortality before the advent of antibiotics.

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Leukemia Leukemia is a disease characterized by the

progressive overproduction of white blood cells which usually appear in the circulating blood in immature form.

Any of the white blood cells may be involved by this disorder, and for this reason the disease is often classified according to the following types:- Myeloid Leukemia-involving granulocytic series. Lymphoid Leukemia-involving lymphocytic series Monocytic Leukemia-involving the monocyte series.

This classification can be modified to indicate the course of the disease, by the application of the terms “acute”, “subacute” and “chronic”.

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Clinical features The acute leukemia is more common in children and

young adults, while chronic leukemia are most frequently seen in adults of middle age or older.

Males are affected more than females.

ACUTE LEUKEMIA The development of acute leukemia is sudden,

characterized by weakness, fever, headache, generalized swelling of lymph nodes, petechial or ecchymotic hemorrhages in the skin and the mucous membranes and evidence of anemia.

Numerous organs such as spleen, kidney and liver become enlarged owing to leukemic infiltration in cases of long duration.

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CHRONIC LEUKEMIA Chronic leukemia develops insidiously that the

disease may be present for months or even several years before the symptoms lead to discovery.

The patient may appear in excellent health or exhibit anemic pallor and emaciation suggestive of chronic debilitating disease.

Lymph node enlargement is common in chronic lymphatic leukemia, but uncommon in myeloid leukemia.

The skin is frequently involved, may manifest petechiae or ecchymosis.

There may be leukemids : papules, pustules, bullae, areas of pigmentation, herpes zoster, itching or burning sensations.

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Oral manifestations These manifestations are more common in acute

stage of the disease, mostly in monocytic leukemia, and lymphocytic leukemia is the least likely to have oral lesions.

The primary clinical manifestations of the disease consist of gingivitis, gingival hyperplasia, hemorrhage, petechiae and ulceration of the mucosa.

Gingival hyperplasia is the constant feature which is usually generalized. The gingivae can be boggy, deep red, bleed easily. In severe cases, the teeth may be almost completely hidden. It is due to leukemic infiltration in areas of mild chronic irritation.

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Oral manifestations

Gingival hyperplasiaPetechiae on the lip surface

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Oral manifestations

Extensive hemorrhagic enlargement of maxillary and mandibular gingivae

Ulcerated soft tissue nodule of hard palate represents leukemic cells that have proliferated in this area

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Laboratory findings

Anemia and Thrombocytopenia are characteristics of both acute and chronic forms.

Both bleeding and clotting time is prolonged. The leukocyte count may be subnormal in early

stages, but rises in the terminal stages to 100,000 or more cells in acute forms and to 500,000 cells in chronic forms.

The differential count is elevated in the cell type involved, and often over 95 percent are leukemic cells.

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Treatment

A wide array of chemotherapeutic drugs, radiation therapy, and corticosteroids under certain circumstances offer prolonged remissions and apparent cures in atleast some forms of the disease.

Bone marrow transplantation has become increasingly popular in young subjects where a histocompatible bone marrow donor is available.

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PLATELETS

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PLATELETS They are the smallest blood cells, colourless,

spherical or oval granulated bodies with no nucleus. Normal count is 1.5 to 4 lacs per cubic millimeters. Life span is 8-12 days. It is of 2-5 μm in diameter with an average volume of

5.8 cubic micrometers. Increase in platelets (thrombocytosis)occurs mainly

after trauma, splenectomy or after epinephrine injection.

Decrease in platelets (thrombocytopenia) occurs in bone marrow depression, hypersplenism, viral infections like dengue fever.

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Purpura

Purpura is defined as a purplish discolouration of the skin and mucous membranes due to spontaneous extravasation of blood.

Purpura may result if the platelets are defective or deficient or due to an unexplained capillary fragility.

Purpura may be classified as: Nonthrombocytopenic purpura Thrombocytopenic purpura – can be of two types :

Primary or essential purpura Secondary or symptomatic purpura

241

Nonthrombocytopenic purpura

As the name indicates, this type of purpura is not mediated through the changes in blood platelets, but rather through alterations in the capillaries that result in increased permeability.

The most common causes of this purpura are: Auto-immune e.g., allergic purpuras, drug induced

vascular purpuras Infections e.g., bacterial(typhoid fever, scarlet fever),

viral(smallpox, influenza, measles), rickettsial(rocky mountain fever, typhus fever)

Structural malformations e.g., hereditary hemorrhagic telangiectasia, hereditary disorders of connective tissue(Ehlers- Danlos syndrome, osteogenesis imperfecta)

242

Thrombocytopenic purpura Thrombocytopenia is a disease in which there is an

abnormal reduction in the number of circulating platelets.

Two basic forms of thrombocytopenia are recognized Primary which is of unknown etiology Secondary which may be due to wide variety of

diseases.

Primary thrombocytopenia is an autoimmune disorder in which a person develops antibodies against its own platelets.

Acute form occurs usually in children following viral infections, chronic form in adults mostly women of childbearing age.

243

Clinical features

It is characterized by spontaneous appearance of purpuric lesions on the skin which vary in size from tiny red, pinpoint petechiae to large purplish ecchymoses and even massive hematomas with bruising tendency.

Epistaxis(bleeding from nose) is common manifestation as are bleeding from urinary tract (hematuria), bleeding from the gastro-intestinal tract(melena or hematemesis).

A possible complication is intracranial hemorrhage. Spleen is not palpable, and if it is palpable, then

leukemia should be suspected.

244

Oral manifestation

One of the prominent feature is profuse gingival hemorrhage which occurs in most cases. It may be spontaneous and often arises in the absence of skin lesions.

Petechiae also occurs on the oral mucosa, commonly on the palate, and appear as numerous, tiny, grouped clusters of reddish spots only a millimeter or less in diameter.

The tendency for excessive bleeding contraindicates any oral surgical procedure, particularly tooth extraction.

245

Clinical features

Petechial patches seen on the patient suffering from thrombocytopenic purpura

This dark palatal lesion represents a hematoma

246

Laboratory findings

It may be exceptionally severe, the platelet count is usually below 60,000 per cubic millimeter.

As a consequence, the bleeding time is prolonged but the clotting time remains normal.

The capillary fragility is increased and the tourniquet test is strongly positive.

The red blood cells and the white blood cells are normal unless secondarily disturbed by frequent episodes of hemorrhage or drug or X-ray induced pancytopenia.

247


There is no specific treatment for this disease, although splenectomy has proved beneficial.

Administration of corticosteroids is another important therapeutic measure.

In palliative therapy, blood transfusions are done in cases severe hemorrhage.

Immunosuppressive agents such as vincristine, azathioprine, or cyclophosphamide are also used.

248

Thrombotic thrombocytopenic purpura This is an uncommon form of thrombocytopenic

purpura which is of obscure nature but may be immunologically mediated.

CLINICAL FEATURES

The disease generally occurs in young adults and is more common in females than in males.

It is characterized by thrombocytopenia, hemolytic anemia, fever, transitory neurologic dysfunction and renal failure.

249

Histologic features

The major findings in this disease are the widespread microthrombi in the arterioles, venules and capillaries in all the tissues and organs in the body.

These intravascular thrombi are composed of aggregates of platelets that become organized into amorphous plugs, which are then replaced by fibrin.

The characteristic microscopic gingival changes are occlusive subintimal deposits of PAS(periodic acid- Schiff)- positive material at arteriocapillary junction.

250

Treatment and prognosis This disease was almost uniformly fatal decades

ago. However, many patients now survive with the help of

modern therapeutic drugs and techniques such as :

Corticosteroids Platelet aggregation inhibitors Splenectomy Exchange transfusions.

251

Blood coagulation and coagulation

disorders

252

Blood coagulation

Coagulation is a complex process by which blood forms clots.

It is an important part of hemostasis (the cessation of blood loss from a damaged vessel), wherein a damaged blood vessel wall is covered by a platelet and fibrin-containing clot to stop bleeding and begin repair of the damaged vessel.

Disorders of coagulation can lead to an increased risk of bleeding (hemorrhage) or clotting (thrombosis)

253

International nomenclature of Blood Coagulation factors

Factor

I

II

III

IV

V

VI

VII

VIII

Preferred synonyms Fibrinogen Prothrombin Tissue thromboplastin Ionized Calcium Proaccelerin / Labile factor Term no longer used Serum prothrombin conversion

accelerator / Convertin Antihemophilic globulin(AHG)

254

International nomenclature of Blood Coagulation factors

Factor

IX

X

XI

XII

XIII

Preferred synonyms Plasma thromboplastin

component(PTC) / Christmas factor Stuart factor Plasma thromboplastin antecedent

(PTA) Hageman factor Fibrin stabilizing factor

255

Mechanism of blood coagulation

256

Mechanism of blood coagulation

Hemostasis is maintained in the body via three mechanisms:

Vasoconstriction - Damaged blood vessels constrict. Platelet plug formation - Platelets adhere to

damaged endothelium to form platelet plug (primary hemostasis) and then degranulate.

Blood coagulation - Clots form upon the conversion of fibrinogen to fibrin, and its addition to the platelet plug (secondary hemostasis).

257

Vasoconstriction

258

Primary hemostasis

259

Platelet Plug Formation

260

Secondary hemostasis

261

Sequence of blood coagulation

The first step is immediate constriction of damaged vessels caused by vasoconstrictive paracrine released by the endothelium.

Vasoconstriction temporarily decreases blood flow and pressure within the vessel.

When you put pressure on a bleeding wound, you also decrease flow within the damaged vessel.

Vasoconstriction is rapidly followed by the second step, mechanical blockage of the hole by a platelet plug.

262


The plug forms as platelets stick to the exposed collagen(platelet adhesion) and become activated, releasing cytokines into the area around the injury.

Platelet factors reinforce local vasoconstriction and activate more platelets which stick to one another (platelet aggregation) to form a loose platelet plug.

Simultaneously, exposed collagen and tissue factor (a protein-phospholipid mixture) initiate the third step, a series of reactions known as the coagulation cascade.

263

The coagulation cascade is a series of enzymatic reactions that ends in the formation of a fibrin protein fibre mesh that stabilizes the platelet plug. The reinforced platelet plug is called a clot.

Some chemical factors involved in the coagulation cascade also promote platelet adhesion and aggregation in the damaged region.

Eventually, as the damaged vessel repairs itself, the clot retracts and is slowly dissolved by the enzyme plasmin


264

Pathways of blood coagulation

266

Platelet rich human blood plasma (left vial) is a turbid liquid. Upon addition of ADP, platelets are activated and start to aggregate, forming white flakes (right vial). At the bottom of both vials is a magnetic stirrer

Aggregation of thrombocytes after addition of ADP.

267

Diseases involving specific blood factors HEMOPHILIA

Also known as Bleeder’s disease, Disease of Kings.

Hemophilia is a blood disease which is characterized by prolonged coagulation time and hemorrhagic tendencies.

The disease is hereditary, the defect being carried by X chromosome, and is transmitted as a sex-linked mendelian recessive trait, thus hemophilia occurs only in males.

268

HEMOPHILIA (contd.)

There are three types of hemophilia : Hemophilia A – deficiency of antihemophilic factor

(factor VIII-one of its components) Hemophilia B – deficiency of plasma thromboplastin

component (factor IX) Hemophilia C – deficiency of plasma thromboplastin

antecedent (factor X)

The most common hemophilia is Hemophilia A. There is an absence of clot-promoting factor in

Hemophilia A.

269

CHARACTERISTICS OF HEMOPHILIOID DISORDERS

DISORDER MODE OF INHERITANCE

PROTHROMBIN TIME

PARTIAL THROMBOPLASTIN

TIME

BLEEDING TIME

HEMOPHILIAA

SEX-LINKED RECESSIVE

NORMAL PROLONGED NORMAL

HEMOPHILIAB

SEX-LINKED RECESSIVE

NORMAL PROLONGED NORMAL

VASCULAR HEMOPHILIA

AUTOSOMAL DOMINANT

NORMAL PROLONGED PROLONGED

270

Inheritance of hemophilia

271

Clinical features

Patients with hemophilia exhibit persistent bleeding, either spontaneous or following even slight trauma that produces the mildest of abrasions or cuts.

Hemorrhage into subcutaneous tissues, internal organs and joints (hemarthrosis) is also a common feature and may result in massive hematomas.

The disease is usually present from birth, but may not become clinically apparent for several years.

Spontaneous cyclic remissions and exacerbations of hemophilia are common.

272

The enlargement of knees of this patient is due to repeated episodes of bleeding into the joints

(hemarthrosis)

273

Oral manifestations Hemorrhage from many sites in the oral cavity is a

common finding in hemophilia, and gingival hemorrhage may be massive or prolonged.

Even the physiologic processes of tooth eruption and exfoliation may be attended with severe prolonged hemorrhage.

Dental extractions are contraindicated in hemophiliacs. Without proper premedication even a minor oral surgical procedure may result in death due to exsanguination.

Tooth extractions by means of rubber bands has often been successfully.

274

Gingiva of a hemophiliac.

275

Spontaneous bleeding gingivae

276

Laboratory findings

The characteristic defect in hemophilia is prolonged coagulation time.

The bleeding time is normal, as is the prothrombin time and platelet aggregation.

In vitro, the deficiency of clot-promoting factor in the plasma of hemophiliacs impairs clotting because it seems to retard development of the substance responsible for conversion of prothrombin to thrombin

277


There is no known cure for hemophilia but the affected person should be protected from traumatic injuries.

Local hemostatic measures must be taken in case of bleeding from small wounds.

Replacement therapy must be given in the form of fresh whole blood or cryoprecipitate must be given in case of profuse bleeding.

Dental extractions or any minor oral surgical procedure should be done in the hospital and must be considered as a major one.

278

Von Willebrand’s disease

It is an inherited disorder of hemostasis which clinically resembles hemophilia.

It is inherited as an autosomal dominant trait which affects both males and females but detected more often in females.

Unlike classic hemophilia, this disease is caused by decreases in all 3 functional components of factor VIII.

279

Clinical features

Excessive bleeding, either spontaneously or following even minor trauma, is the chief feature of the disease.

The commonest sites of bleeding are nose, skin and gingiva.

Bleeding into gastrointestinal tract and severe menorrhagia are also common although hemarthrosis is rare.

The bleeding tendency is often cyclic or sporadic.

280

Oral manifestations

Gingival bleeding can be a feature as it can be spontaneous or occurs after brushing of the teeth.

The disease may be discovered after dental extractions because of prolonged and excessive bleeding.

It may commence at the time of extraction and continue indefinitely or it may begin several hours subsequent to surgery and result in almost unmanageable flow.

281

Laboratory findings The bleeding time in this disease is increased to an

extremely variable degree, and can range between several minutes and one hour.

The coagulation time is usually normal, but may be slightly prolonged.

Prothrombin time is also normal. While the capillary fragility is increased with a

positive tourniquet test. Characteristically, poor platelet adherence is also

demonstrable. Clot retraction is also normal.

282

Treatment

Bleeding episodes are best treated by transfusions of plasma and/or antihemophilic factor (cryoprecipitate) and by local control of hemostasis.

All surgical procedures of unessential nature must be avoided.

Use of oestrogen / progestrone preparations to regulate the menstrual cycle often helps to control menorrhagia.

283

BLOOD GROUPS AND BLOOD TRANSFUSION

284

Blood groups and blood transfusion

The term blood group is applied to any well-defined system of red blood cell antigens which are inherited characteristics.

Over 20 blood group systems having approximately 400 blood group antigens are currently recognized.

The ABO and Rhesus (Rh) blood group systems are of major clinical significance.

Individuals who lack the corresponding antigen and have not been previously transfused have naturally occurring antibodies in their serum. The most important are anti-A and anti-B antibodies.

285

Blood groups : Red cell groups

Antigens Human red blood cells contain on their surface a

series of glycoproteins and glycolipids which constitute the blood group antigens.

ABO system consists of 3 major allelic genes, A,B and O, located on the long arm of chromosome 9.

These genes control the synthesis of blood group antigens A and B.

The serum of an individual contains naturally occuring antibodies to A and/or B antigen, whichever antigen is lacking in person’s red cells.

286

Blood groups : Red cell groups Antibodies Classification

The antibodies to the red cell antigens are of two types :

Naturally occurring antibodies occur without any obvious antigenic stimulus in the serum of individuals lacking the corresponding red cell antigen. The iso-agglutinins of the ABO system are the main example.

Immune or acquired antibodies are produced in individuals as a result of stimulation by a red cell antigen which is not present on their own red cells or in their body fluids.(Blood transfusions)

288

MOST COMMON BLOOD GROUPS IN INDIA

O+

36.5% B+

3 0.9 %

A+

22.1%

AB

+

6.4%

O-

2.0%

B-

1.1%

A-

0.8%A

B-

0.2%

289

ABO COMPATIBILITY

People with blood group O are called "universal donors" and people with blood group AB are called "universal receivers."

290

Rhesus system The Rhesus (Rh) blood group system was first

discovered on human red cells by the use of antisera prepared by immunizing rabbits with red cells from a Rhesus monkey.

The Rh allelic genes are C or c, D or d and E or e, located on chromosome 1.

One set of 3 genes is inherited from each parent giving rise to various complex combinations, the corresponding antigens are similarly named Cc, Ee and only D since no d antigen exists.

However, out of all of these, D antigen is most strongly immunogenic and, therefore, clinically most important.

291

Rhesus system

In practice, Rh grouping is performed with anti-D antiserum.

Individuals who are D-positive are referred to as Rh-positive and those who lack D antigen are termed Rh-negative.

Practically, there are no naturally occurring Rh antibodies. All Rh antibodies in Rh-negative individuals are acquired from immunization such as by transfusion and during pregnancy, resulting in fatal hemolytic transfusion reaction and hemolytic disease of newborn.

292

BLOOD TRANSFUSION

293

Blood transfusion

A pre-transfusion compatibility testing is essential prior to any blood transfusion. The procedure consists of the following : ABO and Rh(D) grouping of the patient (recipient). Antibody screening of the patient’s serum to detect

the presence of clinically significant antibodies. Selecting the donor blood of the same ABO and

Rh group. Cross matching the patient’s serum against donor

red cells to confirm donor-recipient compatibility.

294

Complications of blood transfusion

Transfusion reactions are generally classified into 2 types : Immunologic transfusion reactions may be against

red blood cells (hemolytic reactions), leucocytes, platelets or immunoglobulins.

Non-immune transfusion reactions include circulatory overload, massive transfusion, or transmission of an infectious agent.

295

Transfusion of incompatible blood can be fatal!

296

Immunologic transfusion reactions Hemolytic transfusion reactions.

Hemolytic transfusion reaction may be immediate or delayed, intravascular or extravascular. The very rapid cell destruction associated with

intravascular hemolysis is usually due to ABO incompatibility since both naturally-occurring antibodies, anti-A and anti-B, are capable of fixing complement.

The symptoms include restlessness, anxiety, flushing, chest or lumbar-pain, tachypnoea, tachycardia and nausea, followed by shock and renal failure.

297

Symptoms of acute hemolytic reactions

298

Immunologic transfusion reactions

Extravascular hemolysis is more often due to immune antibodies of the Rh system.

The clinical manifestations are relatively less severe and usually consist of malaise and fever but shock and renal failure may rarely occur.

Some patients develop anemia due to destruction of red cells in the Reticuloendothelial system about a week after transfusion.

Such delayed reactions are generally the result of previous transfusion or pregnancy (anamnestic reaction).

299

Immunologic transfusion reactions

Other allergic reactions

In the absence of hemoglobin reaction, occurrence of some febrile reaction is usually attributed to immunologic reaction against white blood cells, platelets, or IgA class immunoglobulins.

Patients with antibodies against IgA molecule sometimes develop severe shock on transfusion of blood from other human subjects.

300

Non immune transfusion reactions This category includes the following adverse effects:

Circulatory overload

The circulatory overload resulting in pulmonary congestion and acute heart failure is the most important and most common complication that may result in death following transfusion.

The circulatory overload is particularly high in patients with chronic anemia, and in infants and the elderly.

The onset may be immediate, or may be delayed up to 24 hours.

301

Non immune transfusion reactions Massive transfusion

When the volume of stored blood transfused to bleeding patients exceeds their normal blood volume, it results in dilutional thrombocytopenia and dilution of coagulation factors.

Transmission of infection

Many diseases can be transmitted by transfusion of an infected blood. These include: hepatitis (HBV, HCV), CMV infection, syphilis, malaria, toxoplasmosis, infectious mononucleosis, brucellosis and AIDS (HIV infection).

302

Non immune transfusion reactions

Air embolism Air embolism is unlikely to occur if the blood

transfusion is carried out with plastic bags with negative pressure as is the usual practice nowadays.

A debilitated person may develop symptomatic air embolism even if a small volume (10-40 ml) makes its way into the circulation, whereas a healthy individual is at lesser risk.

303


Thrombophlebitis The complication of thrombophlebitis is more

commonly associated with venesection for blood transfusion, especially if it is done in the saphenous vein of the ankle rather than the veins of the arm.

The risk of developing thrombophlebitis is further enhanced if the transfusion is continued longer than 12 hours at a single site.

304

Thrombophlebitis

305


Transfusion hemosiderosis

Post transfusion iron overload with deposition of iron in the tissues of the body occurs after repeated transfusions in the absence of any blood loss e.g., in thalassemia major and in severe chronic refractory anemias.

The body has no other means of getting rid of extra iron except iron excretion at the rate of 1mg per day.

306

Erythroblastosis fetalis

Congenital hemolytic anemia due to Rh incompatibility results from the destruction of fetal blood brought about by a reaction between maternal and fetal blood factors.

It results from the passage of IgG antibodies from the maternal circulation across the placenta into the circulation of the foetal red cells.

Besides pregnancy, sensitization of the mother may result from previous abortions and previous blood transfusion.

307

Pathogenesis Hemolytic disease of newborn(HDN) can occur from

incompatibility of ABO or Rh blood group system. ABO incompatibility is much more common but HDN

in such cases is mild, but it is more severe in Rh incompatibility.

HDN due to Rh-D incompatibility

Rh-incompatibility occurs when a Rh-negative mother is sensitized to Rh-positive blood. This results most often from a Rh-positive foetus by passage of Rh-positive red cells across the placenta into the circulation of Rh-negative mother.

308

Pathogenesis

Normally, during pregnancy very few fetal red cells cross the placenta but haemorrhage during parturition causes significant sensitization of the mother.

It must be emphasized here that the risk of sensitization of a Rh-negative woman married to Rh-positive man is small in first pregnancy but increases during successive pregnancies if prophylactic anti-D immunoglobulin is not given within 72 hours after the first delivery.

309

Sensitization at delivery due to haemorrhage

310

Rh+ Fetal cells enter mother’scirculation at delivery

311

Second pregnancy is attacked bymaternal antibodies

312

Clinical features

The manifestations of the disease depend upon the severity of the hemolysis.

Hemolytic disease of newborn due to Rh incompatibility in its severest form may result in intrauterine death from hydrops fetalis.

Moderate disease produces a baby with severe anemia and jaundice and compensatory erythropoiesis (both medullary and extramedullary) and edema resulting in fetal hydrops.

The most important aid in diagnosis of the disease is a positive direct Coombs test on cord blood.

313

Hydrops fetalis

314

Oral manifestations Erythroblastosis fetalis may be manifested in the

teeth by the deposition of blood pigment in the enamel and dentin of the developing teeth, giving them a green, brown or blue hue.

Ground sections of these teeth give a positive test for bilirubin. The stain is intrinsic and does not involve teeth or portions of teeth developing after cessation of hemolysis shortly after birth.

Enamel hypoplasia is also seen. This usually involves the incisal edges of the anterior teeth and middle portion of the deciduous cuspid and first molar crown. The characteristic ring like defect occurs and termed as Rh hump.

315

Oral manifestations

Diffuse grayish blue discoloration of the dentition. Cervical portions are stained most intensely.

316

Enamel hypoplasia

317

Laboratory diagnosis The red blood count at birth may vary from less than

1 million cells per cubic millimeter to near a normal level.

Cord blood shows large numbers of normoblasts, or nucleated cells, in the circulating blood. With elevated serum bilirubin and a positive direct Coombs test if cord blood is Rh-D positive.

The icterus index is invariably high and may reach a level of 100 units.

318

Erythroblastosis fetalis

319

Treatment

Prophylactic anti-D immunoglobulin should be given within 72 hours after the first delivery.

No treatment is necessary for the tooth pigmentation, since it affects only the deciduous dentition and presents only as a temporary cosmetic problem.

320

Bibliography

1. Textbook of Medical Physiology: By Arthur C.Guyton & John E.Hall(Tenth Edition)

2. Review of Medical Physiology: By William F.Ganong(Twenty second Edition)

3. Human Physiology: By B J Meyer,H S Meij,A C Meyer(Second Edition)

4. De Gruchy’s Clinical Haematology in Medical Practice: By Frank Firkin, David Penington, Colin Chesterman, Bryan Rush(Fifth Edition)

5. Hematology: clinical principles and applications: By Bernadette F. Rodak, George A. Fritsma, Kathryn Doig

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Bibliography

6. A-Z of Haematology: By Bain, Barbara J.

7. Images

http://library.med.utah.edu/WebPath/HEMEHTML/HEME007.html

http://www.hematologyatlas.com

8. Robbin’s Pathological Basis of Diseases-8th edition

9. Essential Pathology for Dental students(2nd edition)-Harsh Mohan

http://www.hematologyatlas.com/

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Bibliography

10. A textbook of Oral Pathology(4th edition) by Shafer W.G, Hine M.K, Levy B.Y

11. Burket’s Oral Medicine Diagnosis and Treatment (tenth edition) By Greenberg M.S., Glick M.

12. O.D. Ratnoff : Bleeding Syndromes : A Clinical Manual. Springfield, Charles C.Thomas, 1960

13. Oral and Maxillofacial Pathology, 3rd Edition By Brad Neville, DDS, Douglas D. Damm, DDS, Carl M. Allen, DDS, MSD and Jerry Bouquot, DDS, MSD

323

Bibliography

14. Hematology: Basic principles and practice

by Ronald Hoffman

15. Cawson's Essentials of Oral Pathology and Oral Medicine by Roderick A. Cawson MD FDSRCS FDSRCPS(Glas) FRCPath FAAOMP (Author), Edward W Odell FDSRCS MSc PhD FRCPath Professor (Author)

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