hemolysis
DESCRIPTION
Hemolysis. Increased cell destruction Rate of destruction exceeds the capacity of the bone marrow to produce red blood cells (RBC) Normal RBC survival time is 110-120 days Approximately 1% of RBC are removed each day and replaced by the marrow to maintain the RBC count. Hemolysis. - PowerPoint PPT PresentationTRANSCRIPT
Hemolysis Increased cell destruction Rate of destruction exceeds the capacity
of the bone marrow to produce red blood cells (RBC)
Normal RBC survival time is 110-120 days
Approximately 1% of RBC are removed each day and replaced by the marrow to maintain the RBC count
During hemolysis RBC survival is shortened and increased marrow activity results in a heightened reticulocyte percentage
Hemolysis can be divided into two Intravascular hemolysis Extravascular hemolysis
Hemolysis
Extravascular hemolysis The degradation of Hb results in the
biliary excretion of heme pigments and increased fecal urobilinogen
Gallstones composed of calcium bilirubinate may be formed in children as young as 4 years of age
Hemolysis
Intravascular hemolysis Hb binds to haptoglobin and hemopexin both of
which are reduced Oxidized heme binds to albumin to form
methemalbumin which is increased When the capacity of these binding molecules is
exceeded, free Hb appears in the plasma (evidence of intravascular hemolysis)
When the tubular reabsorbtive capacity of kidneys for Hb is exceeded free Hb appears in the urine
Hemolysis
Hemolytic anemia Hemolysis
Increased cell destruction A feature of hemolytic anemia is a reduction
in the normal red cell survival of 120 days The premature destruction of RBC may result
from corpuscular abnormalities such as Hb defects, abnormalities of RBC enzymes or
defects of RBC membrane Other defects may result from
extracorpuscular abnormalities and may be due to immune or non-immune mechanisms
The approach to the diagnosis of hemolytic anemia should include Consideration of the clinical features
suggesting hemolytic disease Demonstration of the presence of
hemolytic process by laboratory means Establishment of the presice cause of
the hemolytic anemia by special hematologic investigations
Hemolytic anemia
The following clinical features suggest hemolysis Age: anemia and jaundice in an Rh(+) infant born
to a Rh(-) mother or a group A or B infant born to a group O mother
History of anemia, jaundice or gallstones in family Persistent/ recurrent anemia associated with
reticulocytosis Anemia unresponsive to hematinics Intermittent/persistent indirect hyperbilirubinemia
Hemolytic anemia-Clinical features(1)
Splenomegaly Hemoglobinuria Presence of multiple gallstones Chronic leg ulcers Development of anemia or
hemoglobinuria after exposure to certain drugs
Dark urine
Hemolytic anemia-Clinical features(2)
Reduced cell survival and evidence of accelerated Hb catabolism
Evidence of increased erythropoiesis
Hemolytic anemia-laboratory findings
Accelerated Hb catabolism Extravascular
Raised unconjugated bilirubin Raised fecal and urinary urobilinogen
Intravascular Hemoglobinuria Low/absent plasma haptoglobin Raised plasma methemalbumin
Hemolytic anemia-laboratory findings
Increased erythropoiesis (response to a reduction in Hb) Reticulocytosis Increased MCV Increased normoblasts in peripheral blood Spesific morphological abnormalities
Sickled cells, target cells, spherocytes Erhytroid hyperplasia of bone marrow Expansion of marrow space
Prominence of frontal bones, broad cheek bones, widened intratrabecular spaces, hair-on-end appearance of skull radiographs
Hemolytic anemia-laboratory findings
normal macrocytes
Hypochromic, microcytes
Target cells
schistocytes
Tests used to establish a spesific cause of hemolytic anemia (1) Membrane defects (Hereditary spherocytosis,
elliptocytosis, stomatosis, acantocytosis) Blood smear Increased RBC osmotic fragility
(spherocytes lyse in higher concentrations of saline than normal RBC)
Autohemolysis at 24 and 48 hours Enzyme defects (G6PD and pyruvate kinase)
Heinz body preparation Autohemolysis test Screening tests for enzyme deficiencies
Hemoglobin defects (sickle cell disease, thalassemias) Blood smear, sickle cell, target cell Sickling test Hemoglobin electrophoresis HbF determination
Tests used to establish a spesific cause of hemolytic anemia (2)
Immune hemolytic anemia Isoimmune
Mismatched blood transfusion Hemolytic disease of the newborn
Autoimmune Action of Ig Idiopathic, secondary to number of
conditions Coombs’ test (+)
Tests used to establish a spesific cause of hemolytic anemia (3)
Non-immune hemolytic anemia Infections, drugs, underlying
hematologic disease- microangiopathic HA, hypersplenism
Coombs’ test (-)
Tests used to establish a spesific cause of hemolytic anemia (4)
Congenital hemolytic anemias Membrane defects
Hereditary spherocytosis(HS) Enzyme defects
G6PD deficiency Hemoglobin defects
- thalassemia (quantitative hemoglobinopathies)
HbS (qualitative hemoglobinopathies) Hemolytic disease of the newborn (isoimmune)
ıntracorpuscular
Hereditary spherocytosis Familial hemolytic disorder Marked heterogenicity of clinical features
Asymptomatic condition Fulminant hemolytic anemia
The morphologic hallmark of HS Microspherocyte Caused by loss of membrane surface area Abnormal osmotic fragility
HS usually is transmitted as an autosomal dominant trait
An autosomal recessive mode of inheritance also occurs 20-25% of all HS cases
HS is encountered worldwide
Hereditary spherocytosis
An intrinsic genetic defect causes defects in membrane proteins
The major complications Aplastic or megaloblastic crisis Hemolytic crisis Cholecystitis and cholelithiasis Severe neonatal hemolysis
Hereditary spherocytosis
HS erythrocytes are caused by membrane protein defects resulting in cytoskeleton instability
Four abnormalities in red cell membrane proteins have been identified Spectrin deficiency alone (most common) Combined spectrin and ankyrin deficiency Band 3 deficiency(10-20% of patients) Protein 4.2 defects (common in Japan)
Hereditary spherocytosis- Pathophysiology
Spectrin deficiency Loss of erythrocyte surface
Spherical RBC Culled rapidly from the circulation by the spleen
Splenomegaly Hemolysis primarily confined to the spleen
Extravascular hemolysis Biochemical spectrin deficiency and the degree
of spectrin deficiency are reported to correlate with the extent of spherocytosis, the degree of abnormality on osmotic fragility test results and the severity of hemolysis
Hereditary spherocytosis- Pathophysiology
Ankyrin defects Ankyrin is the principal binding site for spectrin
on RBC membrane A proportional decrease in spectrin content
occurs although spectrin synthesis is normal 75-80% of patients with autosomal dominant HS
have combined spectrin and ankyrin deficiency Deletion of chromosome 8 are shown to have a
decrease in RBC ankyrin content
Hereditary spherocytosis- Pathophysiology
Anemia
Jaundice
Splenomegaly
Hereditary spherocytosis- Clinical findings
Clinical features of HS
Anemia or hyperbilirubinemia may be of such magnitude as to require exchange transfusion in the neonatal period
Anemia is mild to moderate Sometimes severe/not present
In patients with mild HS cholelithiasis may be the first sign of underlying disease
Moderate HS (most common, 60-75%) Mild HS (20-30%) Severe HS (5%, requires RBC transfusions)
Hereditary spherocytosis- Clinical findings(2)
Minimal or no anemia Reticulocytosis Increased MCHC Spherocytes on the peripheral blood smear
Howell-Jolly bodies may be seen Hyperbilirubinemia Abnormal osmotic fragility test
hemolysis of HS cells may be complete at a solute concentration that causes little or no lysis of normal cells
LDH increased Increased unconjugated bilirubin Looking for abnormalities in spectrin, ankyrin,
band 3 (not routine)
Hereditary spherocytosis- Laboratory findings
Neonates Phototherapy/exchange transfusion
Aplastic crisis RBC transfusion
Folic acid supplementation to prevent megaloblastic crisis
Splenectomy (after 6 years of age) Increased Hb level Decreased reticulocyte count Appereance of Howell-Jolly bodies and target cells Thrombocytosis
Hereditary spherocytosis- Treatment
Glucose 6 phosphate dehydrogenase deficiency (G6PD) X-linked disorder
Homozygous women are found in populations in which the frequency of G6PD is high
Heterozygous carrier women can develop hemolytic attacks
Polymorphic with more than 300 reported variants
The highest prevalance rates are found in tropical Africa, the Middle East, some areas of Mediterranean (severe forms)
G6PD enzyme catalyzes the oxidation of glucose-6-phosphate to 6-phosphogluconate while reducing the oxidized form of nicotinamide adenine dinucleotide phosphate (NADP+) to nicotinamide adenine dinucleotide phosphate (NADPH)
Glucose 6 phosphate dehydrogenase deficiency- Pathophysiology
NADPH Protects the cells against oxidative stress Required cofactor in many biosynthetic
reactions Maintains glutathion in its reduced form
Glutathion acts a scavanger for dangerous oxidative metabolites in the cell
Converts harmful hydrogen peroxide to water with the help of glutathion peroxidase
Glucose 6 phosphate dehydrogenase deficiency- Pathophysiology
The most common clinical feature is no symptoms
Symptomatic patients Neonatal jaundice
Appears by age 1-4 days Often requires exchange transfusion
Acute hemolytic anemia Results from stress factors such as oxidative drugs
or chemicals, infection or ingestion of fava beans Jaundice and splenomegaly may be present
during crisis
Glucose 6 phosphate dehydrogenase deficiency- Clinical findings
Anemia Reticulocytosis Activity of G6PD is low (after hemolysis) Indirect hyperbilirubinemia Serum haptoglobin levels will be decreased Formation of bodies which consist of
denaturated hemoglobin Heinz body
Glucose 6 phosphate dehydrogenase deficiency- Laboratory findings
Avoid oxidant drugs Antimalarial drugs, nitrofurantoin,
nalidixic acid, ciprofloxacin,methylene blue, chloramphenicol, phenazopyridine, vit K analogs, sulfonamides, acetanilid, doxorubicine, isobutyl nitratre, naphtalene, phenylhydrazine, pyridoxin
Exchange transfusion RBC transfusion
Glucose 6 phosphate dehydrogenase deficiency- Treatment
Thalassemia (Cooley’s anemia, Mediterranean Anemia) Genetically determined defect in Hb synthesis An inability to manufacture sufficient quantities of
globin chains In the adult there are 3 Hb types normally present
Hb A 22 (95% of total) Hb A2 22 (3% of total) HbF 22 (2% of total)
During fetal life the majority of Hb During embryonic life at least 2 different Hbs are
produced Gowers 2 22 chains Gowers 1 4 chains The manufacture of each of these chains is controlled by
spesific genes
In thalassemia there is a genetic failure in the production of globin chains
Failure of production of and chains is the most common thalassemia
a failure of beta chain production thalassemia
a failure of alpha chain production
Thalassemia
The genes controlling beta chain production are located on chromosome 11
thalassemia major If both genes fail
thalassemia minor If only one gene fails
Beta Thalassemia
Most common of thalassemias Beta chain production is less than normal Alpha chain production continues at a near
normal rate Decreased level of HbA Excess alpha chains stimulates the
increased production of delta chains Increased amount of HbA2
Rate of gamma chain production is greater Increased amount of HbF
Beta Thalassemia minor (Heterozygous) (B+)
Beta Thalassemia minor These patients are not severely anemic These patients can be provided
appropriate genetic counselling Hb, Hct are decreased RBC count is not as low as the Hb and Hct
Bone marrow produce the cells but cannot fill them with Hb
RBCs are microcytic and hypochromic Normal RDW
Beta Thalassemia minor MCV is slightly decreased MCH is decreased MCHC is normal WBC count is normal Reticulocyte count is relatively increased Bone marrow is either normal or undergoes
slight erythroid hyperplasia Serum iron,ferritin is normal Bilirubin slightly increase due to
intramedullary hemolysis
Hb studies HbA decreased HbA2 increased HbF slightly increased to normal
Beta Thalassemia minor
Complete failure of beta chain production Raised levels of HbA2 and HbF
HbF has a very high affinity for oxygen (poor oxygen deliverer)
Only functional Hb is HbA2 The patient is hypoxic
İncreased erythropoietin production Stimulates the marrow to maximum
Typical facial appereance Splenomegaly
Extramedullary hemopoiesis
Beta Thalassemia major(homozygous)(B0)
Beta Thalassemia major Patients develop a life threatening anemia by
one or two months (mostly often 6 months) Severe anemia (Hb:2-3 mg/dl)
Hct and RBC count are also decreased MCV, MCH, MCHC are all decreased RDW is increased Hypochromic microcytic RBC
Anisocytosis, poikilocytosis, target cells Reticulocytosis WBC is increased at the beginning
Beta Thalassemia major Bone marrow undergoes erythroid
hyperplasia Serum Fe increased/normal Ferritin increased/normal Hb electrphoresis
HbA decreased HbA2 variable HbF increased
The patients must be supported with blood transfusions which result in iron overload
Unless iron is removed with appropriate chelation therapy these patients die of hemosiderosis
Splenectomy When the yearly transfusion requirement of
packed red cells exceeds 200-250 ml/kg Bone marrow transplantation
Beta Thalassemia major
Alpha thalassemia Four genes coding for alpha chain
production These genes are located on
chromosome 6 There are at least five forms of
alpha thalassemia depending on the number and location of abnormal genes
All genes are abnormal There is no alpha chain production
No HbF production and death in utero At autupsy the cord blood shows severe
anemia There is no HbA and HbF on
electrophoresis most of the Hb is HbBart’s which consists of
4 gamma chains
Hydrops fetalis- Homozygous alpha thalassemia
Hemoglobin H disease Three genes are abnormal and one gene is
coding for alpha chains Limited production of HbF in utero and HbA
after birth The excess gamma chains form HbBart’s and
the excess beta chains form HbH Unstable hemoglobins precipitate in the cell Premature destruction in the marrow and spleen
with splenomegaly Infant is anemic at birth RBC and hct count are also decreased
MCV, MCHC, MCH decreased RDW is increased Microcytosis, hypochromia Reticulocyte count is slightly increased Bone marrow undergoes erythroid
hyperplasia Serum iron,ferritin increased Hb electrophoresis
Hb Bart’s increased at birth Hb Bart’s 2-10% later HbH 5-40% HbA and A2 decreased
Hemoglobin H disease
Heterozygous alpha thalassemia (minor) Depends on whether or not the two deleted genes
are on the same chromosome In alpha th O, both genes are absent from the same
chromosome In alpha th +, one gene is missing from each
chromosome In both forms
Minor changes Mild anemia MCV and MCHC are borderline low
Hb electrophoresis is normal with increased levels of HbBart’s if the cord blood is electrophoresed
Alpha thalassemia silent Only one of the four genes is
abnormal There is a near normal production
of alpha chains with very few if any clinical or laboratory changes
Beta thalassemia variants Delta/beta th
Similar to beta th Symptoms are milder HbA decreased HbF 5-15% HbA2 normal
HbLepore No normal beta or delta chain HbF 80-90% HbA absent HbA2 absent HbLepore 10%
(Homozygous) clinical and lab.findings are identical to Beta th
HbLepore HbA decreased HbA2 decreased HbLepore 10%
Beta thalassemia variants
(Heterozygous) clinical and lab.findings are identical to Beta th minor
Sickle cell anemia Qualitative hemoglobinopathy Valine is substituted instead of glutamine in
the sixth position on the globin molecule Sickle cell anemia is caused by
homozygosity for the sickle cell gene and is the most common form of sickle cell disease
The charge at this site is altered and allows for polymerization of Hb under conditions of hypoxia
Polymerization of sickle Hb distorts erythrocyte morphology causing a marked reduction in RBC
life span increases blood viscosity predisposes to episodes of
vasoocclusion
Sickle cell anemia
Children are normal at birth Onset of symptoms is unusual before 3-4
months of age High levels of HbF inhibits sickling
Moderately severe hemolytic anemia is often present by age 1 year
Pallor,fatigue, jaundice Predispozition to the development of
gallstones
Sickle cell anemia-clinical findings
Intense congestion of the spleen with sickled cells may cause splenomegaly in early childhood and results in functional asplenia as early as age 3
months Great risk for infection with encapsulated bacteria
Acute splenic sequesteration Sudden enlargement of spleen with pooling of red
cells Acute exacerbation of anemia, shock, death
Aplastic crisis Caused by infection with human parvovirus
Sickle cell anemia-clinical findings
Vasoocclusive crisis Hand-foot syndrome Abdominal pain Musculoskletal pain Stroke Acute chest syndrome
Fever, pleuritic chest pain, acute pulmonary infiltrates
Sickle cell anemia-clinical findings
Decreased Hb (7-10 g/dl) with normal MCV
Reticulocytosis Characteristic sickle cells Hb electrophoresis
HbS (SCA with 0 th; HbF and S) (sickle +th;HbS with lesser HbA)
Most infants with sickle hemoglobinopathies born in USA are now identified by neonatal screening
Sickle cell anemia-laboratory findings
Patient and family education Prevention of complications and
optimization of health All children should be immunized with
the conjugate pneumococcal vaccine At the age of 2 months all children
should begin penicillin prophylaxis At least at 5 years of age
Sickle cell anemia-treatment
Treatment of painful vaso-occlusive episodes Adequate hydration Correction of acidosis if present Administration of analgesics Maintenance of normal oxygen saturation Treatment of associated infection
RBC transfusion In acute exacerbation
Exchange transfusion Hydroxyurea Bone marrow transplantation
Sickle cell anemia-treatment
Sickle cell trait Individuals who are heterozygous
for the sickle gene Hb electrophoresis
HbA 60% HbS 40% Normal levels of A2 and F
No anemia, no hemolysis
Exposure to environmental hypoxia may precipitate splenic infarction or sequestration
Sudden death during exercise? Hematuria Bacteriuria Intraocular bleeding Genetic counselling is important
Sickle cell trait
HbE Hemoglobinopathy (not a thalassemia) Production of abnormal globin chains Beta chain variant in which lysine is
substituted for glutamic acid in position 26
Mild anemia Reticulocyte count slightly increased Serum iron, ferritin increased/normal
The catabolism of 1 gr Hb yields 35 mg of bilirubin
Red blood cell of the newborn has a shortened life span= 70-90 days Significant bilirubin load
Albumin binding of unconjugated bilirubin may be important in the prevention of toxicity (kernicterus)
In the hypoglycemic infant, glucuronide production may be limited and thus conjugation is impaired
The presence of β-glucuronidase in the bowel lumen during fetal life enables bilirubin to be reabsorbed and transported across the placenta for excretion by the maternal liver
Overproduction of bilirubin-Hemolytic disease of the newborn Blood group incompatibilities such as Rh,
ABO or minor blood groups exist between a mother and her fetus
Rh(-) mother can become sensitized to the Rh Antigen Improperly matched blood transfusion Occurance of fetal-maternal blood transfusion
During pregnancy, delivery, abortion, amniocentesis
Hemolytic disease of the newborn Rh antigen Maternal antibody production IgG crosses placenta into the fetal
circulation Reacts with the Rh Ag on fetal erythrocytes These antibody coated cells are recognized
as abnormal and are destroyed by the spleen
Production of bilirubin
Hemolytic disease of the newborn Mild hemolysis Severe anemia, erythroblastosis fetalis Cardiac decompensation, massive
anasarca, circulatory collapse Hydrops fetalis (abnormal fluid in two or
more fetal compartments) The use of anti-D gammaglobulin
(rhoGam) including antenatal administration at 26-28 weeks’ gestation
ABO incompatibility ABO incompatibility is limited to
mothers of blood group O and affects infants of blood group A or B
All group O individuals have naturally occurring anti-A and anti-B antibodies, previous sensitization is not necessary
Clinical disease is milder
spherocytosis eliptocytosis
poikilocytosis
stomatocytosis
acanthocytosis Fragmentation
hemolysis
Sickle cell anemia; target cells and sickled cells
Normal RBC
Target cells Heinz body anemia
Thalassemia; severe hypochromia
Anisopoikilocytosis, target cells
normal macrocytes
Hypochromic, microcytes
Target cells
schistocytes