clinical biochemistry 3 biochemical investigation of kidneys function

CLINICAL BIOCHEMISTRY 3CLINICAL BIOCHEMISTRY 3

BIOCHEMICAL INVESTIGATION BIOCHEMICAL INVESTIGATION OF KIDNEYS FUNCTIONOF KIDNEYS FUNCTION

KIDNEY PHYSIOLOGY KIDNEY PHYSIOLOGY

1. 1. EXCRETIONEXCRETION 1.1. GLOMERULAR - FILTRATION1.1. GLOMERULAR - FILTRATION

1.2. TUBULAR – REABSORPTION, SECRETION1.2. TUBULAR – REABSORPTION, SECRETION

2. 2. HOMEOSTATIC HOMEOSTATIC 2.1. WATER-ELECTROLYTE HOMEOSTASIS 2.1. WATER-ELECTROLYTE HOMEOSTASIS

2.2. ACID-BASE HOMEOSTASIS 2.2. ACID-BASE HOMEOSTASIS

2.3. EXCRETION OF NONPROTEIN NITROGENEOUS 2.3. EXCRETION OF NONPROTEIN NITROGENEOUS COMPOUNSCOMPOUNS

3. 3. ENDOCRINEENDOCRINE3.1. PRIMARY: RENIN, PROSTAGLANDINS, ERYTHROPOIETIN3.1. PRIMARY: RENIN, PROSTAGLANDINS, ERYTHROPOIETIN

3.2. SECONDARY3.2. SECONDARY

KIDNEY PHYSIOLOGY KIDNEY PHYSIOLOGY 1. 1. EXCRETIONEXCRETION1.1. GLOMERULAR FILTRATION 1.1. GLOMERULAR FILTRATION

The role to maintain the cellular elements and protein macromolecules in The role to maintain the cellular elements and protein macromolecules in the blood, producing a fluid that is plasma-like but with no proteins. This is the blood, producing a fluid that is plasma-like but with no proteins. This is performed by a semipermeable membrane that:performed by a semipermeable membrane that:

– Allows the free movement of the water, electrolytes and small molecules that Allows the free movement of the water, electrolytes and small molecules that are dissolved (urea, creatinine, glucose, aminoacids) butare dissolved (urea, creatinine, glucose, aminoacids) but

– Does not allow the passing of most of molecules.Does not allow the passing of most of molecules.

The kidneys get 1200-1500 ml of blood/min The kidneys get 1200-1500 ml of blood/min The glomeruli filter The glomeruli filter 125-130 ml/min (glomerular filtration rate = GFR125-130 ml/min (glomerular filtration rate = GFR) ) important for the evaluation of the kidney functionimportant for the evaluation of the kidney functionNormally, the daily urine output is approximate 1500 ml representing 1% of Normally, the daily urine output is approximate 1500 ml representing 1% of the glomerular filtratethe glomerular filtrateThe GFR is estimated by measuring the clearance of a substance that is The GFR is estimated by measuring the clearance of a substance that is eliminated only through glomerular filtration, neither reabsorbed, nor eliminated only through glomerular filtration, neither reabsorbed, nor secreted. secreted.

1.2.1. Proximal convoluted tubule1.2.1. Proximal convoluted tubule::

Reabsorption Reabsorption – substances from the glomerular filtrate: substances from the glomerular filtrate:

¾ of Na and water¾ of Na and water

totally glucosetotally glucose

most of aminoacidsmost of aminoacids

varied amounts of electrolytes (Mg, Ca, K, Cl, HCOvaried amounts of electrolytes (Mg, Ca, K, Cl, HCO33--) and small molecules ) and small molecules

(proteins, uric acid, urea)(proteins, uric acid, urea)

– Implies varied mechanisms:Implies varied mechanisms:active transport (needs energy to transport against a concentration difference): the active transport (needs energy to transport against a concentration difference): the majoritymajority

passive transport (no need of energy, by simplediffusion): urea, Cl, waterpassive transport (no need of energy, by simplediffusion): urea, Cl, water

for some substances (glucose, bicarbonates, phosphates) there is a reabsorptin for some substances (glucose, bicarbonates, phosphates) there is a reabsorptin tresholdtreshold

Secretion:Secretion:– KK++, H, H++, ammonia, uric acid, certain organic bases, medicines (penicillin), ammonia, uric acid, certain organic bases, medicines (penicillin)

– active or passive mechanismactive or passive mechanism

KIDNEY PHYSIOLOGYKIDNEY PHYSIOLOGY1.2. 1.2. TUBULES FUNCTION – REABSORPTION AND SECRETIONTUBULES FUNCTION – REABSORPTION AND SECRETION

KIDNEY PHYSIOLOGYKIDNEY PHYSIOLOGY1.2. 1.2. TUBULES FUNCTIONTUBULES FUNCTION

1.2.2. 1.2.2. Henle :Henle :Descendent part, Descendent part, narrow, descendes into the medulla into a hypertonic medium narrow, descendes into the medulla into a hypertonic medium thus thethus the water water is passively reabsorbed from the tubule fluid to the medulla is passively reabsorbed from the tubule fluid to the medulla Ascendent partAscendent part, larger, reaches the cortex; , larger, reaches the cortex; – The tubule membrane becomes less permeable for the water andThe tubule membrane becomes less permeable for the water and– Actively reabsorbes Actively reabsorbes Cl Cl andand Na Na from the tubular fluid to the renal interstitium from the tubular fluid to the renal interstitium

Thus the urine becomes gradually more hypertonic in the descendent part and Thus the urine becomes gradually more hypertonic in the descendent part and more diluted in the ascending part, retaining the water and eliminating the saltmore diluted in the ascending part, retaining the water and eliminating the salt

1.2.3. 1.2.3. Distal ConvolutedDistal Convoluted TubuleTubule: here the final stage of optimal concentration control : here the final stage of optimal concentration control takes place for the balance of fluids and electrolytes.takes place for the balance of fluids and electrolytes.Reabsorption: small amounts of Reabsorption: small amounts of salt, water, bicarbonatessalt, water, bicarbonates Secretion: Secretion: uric acid, ammonia, Huric acid, ammonia, H++

This is the action place for This is the action place for

– aldosteron - ↑ reabsorption of Na and secretion of Kaldosteron - ↑ reabsorption of Na and secretion of K– ADH - ↑ permeability and water reabsorptionADH - ↑ permeability and water reabsorption

1.2.4. 1.2.4. CollectorCollector Duct:Duct:– ADH controls water reabsorption - determines urine concentrationADH controls water reabsorption - determines urine concentration– Aldosteron controls Na reabsorption Aldosteron controls Na reabsorption

KIDNEY PHYSIOLOGYKIDNEY PHYSIOLOGY1.2. 1.2. TUBULES FUNCTIONTUBULES FUNCTION

Plasmatic renal flux (PRF) Plasmatic renal flux (PRF) is the total amount of plasma that passes is the total amount of plasma that passes through the kidneys during 1 minutethrough the kidneys during 1 minute

Normally it is 625ml/minNormally it is 625ml/min

The tubular secretion capacity is estimated by measuring the clearance The tubular secretion capacity is estimated by measuring the clearance of a substance that is freely filtrated through the glomeruli and of a substance that is freely filtrated through the glomeruli and reabsorbed at the first passage (e.g. para-aminohypuric acid is 90% reabsorbed at the first passage (e.g. para-aminohypuric acid is 90% reabsorbedreabsorbed

KIDNEY FUNCTIONKIDNEY FUNCTION2. REGULATORY FUNCTION 2. REGULATORY FUNCTION 2.1. 2.1. WATER-ELECTROLYTE HOMEOSTASISWATER-ELECTROLYTE HOMEOSTASIS

2.1.1. 2.1.1. WATER BALANCEWATER BALANCE

The kidney regulates the water amount by controling the diuresisThe kidney regulates the water amount by controling the diuresis

In spite of extreme individual variations of food, water and salt intake, loss In spite of extreme individual variations of food, water and salt intake, loss through perspiration, feces, the concentration of dissolved substances in through perspiration, feces, the concentration of dissolved substances in plasma and other biological fluids is maintained between physiological plasma and other biological fluids is maintained between physiological limits.limits.

This control is performed of the balance between 2 mechanisms:This control is performed of the balance between 2 mechanisms:- water intake –under the action of thirst center in the hypothalamuswater intake –under the action of thirst center in the hypothalamus- Water excretion influenced by the tubular reabsorption (contolled by the Water excretion influenced by the tubular reabsorption (contolled by the

ADH)ADH)

For example:For example:– In dehydration, the renal tubules reabsorb the water with a maximal rate, In dehydration, the renal tubules reabsorb the water with a maximal rate,

resulting a low volume of very concentrated urine resulting a low volume of very concentrated urine (osmolality >1200 mOsmol/Kg)(osmolality >1200 mOsmol/Kg)

– In hyperhydration, the renal tubules absorb with a minimal rate, resulting a In hyperhydration, the renal tubules absorb with a minimal rate, resulting a high volume of diluted urine (high volume of diluted urine (osmolality< 50 mOsmol/Kgosmolality< 50 mOsmol/Kg))

2.1. 2.1. WATER-ELECTROLYTE HOMEOSTASISWATER-ELECTROLYTE HOMEOSTASIS

2.1.2. 2.1.2. IONIC BALANCEIONIC BALANCE::NaNa++ (main extracellular cation) (main extracellular cation)– Filtered by the glomerulus Filtered by the glomerulus – Actively reabsorbed especially in the proximal convoluted tubule (pct), exchanced with HActively reabsorbed especially in the proximal convoluted tubule (pct), exchanced with H++

– The balance is controlled by the renin-angiotensin-aldosteron systemThe balance is controlled by the renin-angiotensin-aldosteron systemKK++ (main intracellular cation) (main intracellular cation)– Freely filtered by the glomerulusFreely filtered by the glomerulus– Actively reabsorbed in the nephron (except the descendent Henle loop ); the reabsorption Actively reabsorbed in the nephron (except the descendent Henle loop ); the reabsorption

in the distal convoluted tubules (dct) and collector tubes is controlled by the aldosteronin the distal convoluted tubules (dct) and collector tubes is controlled by the aldosteron– It is in competition with HIt is in competition with H++ for the exchange with Na for the exchange with Na++ in the pct; this is used to preserve H in the pct; this is used to preserve H ++

and compensate the metabolic alkalosis.and compensate the metabolic alkalosis.ClCl-- (main extracellular anion) (main extracellular anion)– Filtered by the glomerulus Filtered by the glomerulus – Passively reabsorbed when NaPassively reabsorbed when Na++ is reabsorbed in the pct. is reabsorbed in the pct.– In the ascending Henle loop the Cl pump acts, reabsorbing the Na, too. In the ascending Henle loop the Cl pump acts, reabsorbing the Na, too.

PhosphatePhosphate (equally intra and extracellular, protein-bound or free) (equally intra and extracellular, protein-bound or free)– The regulation is determined by the reabsorption in pct, controlled by the PTHThe regulation is determined by the reabsorption in pct, controlled by the PTH

CalciumCalcium (intracell, the most important cellular messinger free or protein-bound) (intracell, the most important cellular messinger free or protein-bound)– The free calcium is The free calcium is

ionized, physiologically active – freely filtered by the glomerulus, reabsorbed in the pct, controlled ionized, physiologically active – freely filtered by the glomerulus, reabsorbed in the pct, controlled by PTHby PTHnonionized, complexed with phosphates, bicarbonatesnonionized, complexed with phosphates, bicarbonates

Magnezium Magnezium (intracellular cation, enzyme cofactor, free or protein-bound)(intracellular cation, enzyme cofactor, free or protein-bound)– The free Mg is freely filtered by the glomerulus and reabsorbed in pct, influenced by PTHThe free Mg is freely filtered by the glomerulus and reabsorbed in pct, influenced by PTH

KIDNEY PHYSIOLOGYKIDNEY PHYSIOLOGY2.2. 2.2. ACID-BASE BALANCEACID-BASE BALANCEA great amount of nonvolatile acids are daily formed: carbonic acid, lactic A great amount of nonvolatile acids are daily formed: carbonic acid, lactic acid, ketoacids; they are transported by the plasma and excreted with acid, ketoacids; they are transported by the plasma and excreted with minor changes of physiologic pH.minor changes of physiologic pH.Regenerating the Regenerating the bicarbonatebicarbonate ions: ions:– The bicarbonate is filtered by the glomerulus, is combined with HThe bicarbonate is filtered by the glomerulus, is combined with H+ and + and forms forms

carbonic acid that is degraded to COcarbonic acid that is degraded to CO22 si H si H22OO– COCO22 diffuses in the pct cells where it is converted by carbonic anhydrase to diffuses in the pct cells where it is converted by carbonic anhydrase to

carbonic acid; this is degraded to Hcarbonic acid; this is degraded to H++ and regenerates the bicarbonate which is and regenerates the bicarbonate which is transported in the blood to take place of the one that was used. The protons are transported in the blood to take place of the one that was used. The protons are secreted back to the tubules, in the urinesecreted back to the tubules, in the urine

The excretion of the acids:The excretion of the acids:– HH++ are formed in the process of bicarbonate regeneration are formed in the process of bicarbonate regeneration– They are cleared in more reactions:They are cleared in more reactions:

The ammonia is formed in the renal tubules when the glutamine is deaminated under The ammonia is formed in the renal tubules when the glutamine is deaminated under the action of glutaminase; the ammonia reacts with Hthe action of glutaminase; the ammonia reacts with H++ and Cl and Cl-- forming NH forming NH44Cl Cl (excreted in the urine)(excreted in the urine)

HPOHPO442-2- is filtered in the glomerulus; Na is filtered in the glomerulus; Na22HPOHPO4 4 + H+ H++→NaH→NaH22POPO4 4 ++ NaNa++;; NaNa+ + is combined is combined

with the bicarbonate and is reabsorbedwith the bicarbonate and is reabsorbed

– Acids can be cleared up to urine pH 4.4; then, the metabolic acidosis is Acids can be cleared up to urine pH 4.4; then, the metabolic acidosis is installed.installed.

KIDNEY PHYSIOLOGYKIDNEY PHYSIOLOGY2.3. 2.3. NONPROTEIN NITROGENOUS COMPOUNDS BALANCENONPROTEIN NITROGENOUS COMPOUNDS BALANCE (NPN) (NPN)

NPN result from the metabolism of aminoacids, proteins, nucleic acidsNPN result from the metabolism of aminoacids, proteins, nucleic acids

2.3.1. 2.3.1. UREAUREA (75% of NPN) (75% of NPN)

Filtered, reabsorbed 40-70% in pct; Filtered, reabsorbed 40-70% in pct;

It is not a sensitive indicator for the kidney function It is not a sensitive indicator for the kidney function

2.3.2. 2.3.2. CREATININECREATININE

Formed by dehydration of 2% of the muscular creatine Formed by dehydration of 2% of the muscular creatine

Filtered in glomerulus; a very small amount is reabsorbed and secretedFiltered in glomerulus; a very small amount is reabsorbed and secreted

2.3.3. 2.3.3. URICURIC ACIDACID

Result of the oxidative degradation of the purine nucleosides Result of the oxidative degradation of the purine nucleosides

KIDNEY PHYSIOLOGYKIDNEY PHYSIOLOGY3. 3. ENDOCRINE FUNCTIONENDOCRINE FUNCTION

3.1. PRIMARY3.1. PRIMARYRENINRENIN – Produced by the cells of the juxtaglomerular apparatus of the medullaProduced by the cells of the juxtaglomerular apparatus of the medulla– When the extracellular volume decreasesWhen the extracellular volume decreases– Initial component of renin-angiotensin-aldosteron system; catalyzes the synthesis of Initial component of renin-angiotensin-aldosteron system; catalyzes the synthesis of

angiotensin by the scission of plasma angiotensinogen angiotensin by the scission of plasma angiotensinogen – Function: constrictor of the blood vessels (increases the blood pressure), modifies Function: constrictor of the blood vessels (increases the blood pressure), modifies

serum Naserum Na++ and K and K++

PROSTAGLANDINSPROSTAGLANDINS– As well as leukotriens and thromboxans, are produced in the renal medulla from As well as leukotriens and thromboxans, are produced in the renal medulla from

arachidonic acid by cyclo-oxygenase metabolismarachidonic acid by cyclo-oxygenase metabolism– acts on the blood flowacts on the blood flow

ERYTHROPOIETINERYTHROPOIETIN– is considered to be formed by the transformation of a hepatic protein that is transported is considered to be formed by the transformation of a hepatic protein that is transported

in the plasma, catalyzed by erythrogenin, a renal enzymein the plasma, catalyzed by erythrogenin, a renal enzyme– function: acts on the cells in the bone marrow, increases the synthesis of heme and its function: acts on the cells in the bone marrow, increases the synthesis of heme and its

fixing in the erythrocytes fixing in the erythrocytes

3.2. SECONDARY3.2. SECONDARYPlace for Place for aldosteron actionaldosteron actionCatabolism of Catabolism of insuline, glucagon, aldosteroninsuline, glucagon, aldosteronActivation of Activation of vitamine Dvitamine D (control of the metabolism of calcium and phosphate) (control of the metabolism of calcium and phosphate)

PATHOPHYSIOLOGYPATHOPHYSIOLOGY

Glomerulus diseasesGlomerulus diseases– acute glomerulonefritisacute glomerulonefritis– Chronic glomerulonefritis Chronic glomerulonefritis – Nephrotic syndromeNephrotic syndrome

Tubular diseasesTubular diseasesUrinary tract diseasesUrinary tract diseases– InfectionsInfections– ObstructionsObstructions– LithiasisLithiasis

Renal failureRenal failure– AcuteAcute– chronicchronic

Diabetic nephropathy Diabetic nephropathy Renal hypertension Renal hypertension

BIOCHEMICAL EVALUATION OF THE KIDNEY FUNCTIONBIOCHEMICAL EVALUATION OF THE KIDNEY FUNCTION

Urinalysis: volume, colour, aspect, odour, density, pH, Urinalysis: volume, colour, aspect, odour, density, pH, glucose, proteins, ketone bodies, nitrites, bilirubin, glucose, proteins, ketone bodies, nitrites, bilirubin, urobilinogenurobilinogen

Sediment examination: cells, bacteria, cylinders, crystals,Sediment examination: cells, bacteria, cylinders, crystals,

Examination of urine/24 hoursExamination of urine/24 hours

Electroforesis of urine proteinsElectroforesis of urine proteins

Nonprotein nitrogenous compounds: creatinine, urea, uric Nonprotein nitrogenous compounds: creatinine, urea, uric acidacid

Clearance of Clearance of ββ22-microglobuline (-microglobuline (ββ22-M)-M)

MICROSCOPIC EXAMINATION OF THE URINE SEDIMENTMICROSCOPIC EXAMINATION OF THE URINE SEDIMENT

Microscopic examination of urinary sediment is important because it yields Microscopic examination of urinary sediment is important because it yields information that may be helpful in making a diagnosis.information that may be helpful in making a diagnosis.

For best results, obtain a concentrated specimen (upon arising) that has For best results, obtain a concentrated specimen (upon arising) that has been clean-voided. The specimen should be examined within an hour of been clean-voided. The specimen should be examined within an hour of voiding because cells deteriorate upon standing; this process may be voiding because cells deteriorate upon standing; this process may be delayed by refrigeration or by the addition of formalin (0.2 ml/dl urine).delayed by refrigeration or by the addition of formalin (0.2 ml/dl urine).

Procedure:Procedure:

Centrifuge 10 ml of urine for 5 minutes. 9 ml of the supernatant is Centrifuge 10 ml of urine for 5 minutes. 9 ml of the supernatant is discarded by decanting and the remaining 1 ml is used to resuspend the discarded by decanting and the remaining 1 ml is used to resuspend the sediment. One drop is removed with a pipet, placed on a labeled glass sediment. One drop is removed with a pipet, placed on a labeled glass slide and topped with a cover slip.slide and topped with a cover slip.

MICROSCOPIC EXAMINATION OF THE URINE SEDIMENTMICROSCOPIC EXAMINATION OF THE URINE SEDIMENT

Normal Findings:Normal Findings:

Red blood cells (RBCRed blood cells (RBCSS, erythrocytes), occasional or rare have no , erythrocytes), occasional or rare have no

pathological significance.pathological significance.

White blood cells (WBCWhite blood cells (WBCSS, leukocytes) have no pathological significance if , leukocytes) have no pathological significance if

occasional or rare.occasional or rare.

Epithelial cells:Epithelial cells:

squamous epithelial cells (from the lower urinary tract), have no squamous epithelial cells (from the lower urinary tract), have no particular significance;particular significance;

transitional epithelial cells (lining the renal pelvis, ureters, urinary transitional epithelial cells (lining the renal pelvis, ureters, urinary bladder, proximal urethra), few are expected to be present.bladder, proximal urethra), few are expected to be present.

Hyaline casts (containing proteins) may be found particularly after stress, Hyaline casts (containing proteins) may be found particularly after stress, exercise or fever, in the absence of renal disease.exercise or fever, in the absence of renal disease.

Bacteria may be present as an external contamination; clean-voided Bacteria may be present as an external contamination; clean-voided specimens examined when they are fresh help to eliminate possible specimens examined when they are fresh help to eliminate possible confusion.confusion.

Abnormal Formed Elements:Abnormal Formed Elements:

Cells:Cells:Red blood cells more than occasional may originate from any location in the urinary tract (in Red blood cells more than occasional may originate from any location in the urinary tract (in women can be of genital origin);women can be of genital origin);

White blood cells in large number in freshly voided urine indicate the presence of an White blood cells in large number in freshly voided urine indicate the presence of an infection in genitourinary tract.infection in genitourinary tract.

Yeasts are common contaminats but can cause infections in diabetics with Yeasts are common contaminats but can cause infections in diabetics with glycosuria, in patients trated vigorously with antibiotics.glycosuria, in patients trated vigorously with antibiotics.

Oval fat bodies, thought to be degenerated tubular epithelial cells, filled with fat Oval fat bodies, thought to be degenerated tubular epithelial cells, filled with fat droplets, are usually present in all types of diseases of renal parenchyma but are droplets, are usually present in all types of diseases of renal parenchyma but are characteristic to nephrotic syndrome.characteristic to nephrotic syndrome.

Casts formed by precipitation of mucoprotein in the lumen of tubules and collecting Casts formed by precipitation of mucoprotein in the lumen of tubules and collecting ducts pass into urine. They frequently entrap cells.ducts pass into urine. They frequently entrap cells.Red blood cell casts, present red cells in the protein matrix, are reddish-brown or orange Red blood cell casts, present red cells in the protein matrix, are reddish-brown or orange and denote glomerular inflammation and bleeding (glomerulonephritis, systemic lupus and denote glomerular inflammation and bleeding (glomerulonephritis, systemic lupus erythematosus with kidney involment, other glomerular diseases.erythematosus with kidney involment, other glomerular diseases.

White blood cell casts contain imbedded leukocytes and signify infection (pyelonephritis).White blood cell casts contain imbedded leukocytes and signify infection (pyelonephritis).

Hyaline casts contain protein and are found in the urine when there is proteinuria.Hyaline casts contain protein and are found in the urine when there is proteinuria.

Granular casts contain epithelial cellular debris. Granular casts contain epithelial cellular debris.

Fatty casts indicate a renal parenchymal disease.Fatty casts indicate a renal parenchymal disease.

Waxy casts are cellular casts that have degenerated and look like ground glass and may be Waxy casts are cellular casts that have degenerated and look like ground glass and may be present in a number of kidney diseases.present in a number of kidney diseases.

Broad casts formed in the broad collecting tubules and are found only in renal failure.Broad casts formed in the broad collecting tubules and are found only in renal failure.

Crystals:Crystals:

urate or uric acid crystals in large amount may indicate excessive urate or uric acid crystals in large amount may indicate excessive breakdown of the tissue cells (nucleoproteins) or be an accompaniament breakdown of the tissue cells (nucleoproteins) or be an accompaniament of gout;of gout;

aminoacids: leucine and tyrosine in severe liver disease, cystine in an aminoacids: leucine and tyrosine in severe liver disease, cystine in an inherited metabolic affection (cystinuria);inherited metabolic affection (cystinuria);

hemosiderin after hemolytic episodes;hemosiderin after hemolytic episodes;

sulfonamides, pyridium after medication.sulfonamides, pyridium after medication.

PROTEINS IN URINEPROTEINS IN URINEGlomerular filtrate contains 10-20 mg/dl proteins; a part of them are Glomerular filtrate contains 10-20 mg/dl proteins; a part of them are

reabsorbed (quasicompletely - the albumins, partially - the lizozim, not reabsorbed (quasicompletely - the albumins, partially - the lizozim, not reabsorbed - the amylase). At renal level the proteins can be synthesized, reabsorbed - the amylase). At renal level the proteins can be synthesized, too. Thus, 50 - 100 mg of proteins are eliminated daily, being of too. Thus, 50 - 100 mg of proteins are eliminated daily, being of plasmatic, renal or tissular origin (urinary tract, prostate epithelium).plasmatic, renal or tissular origin (urinary tract, prostate epithelium).Normal centrifuged urine contains 20-40 mg protein/L, which cannot be Normal centrifuged urine contains 20-40 mg protein/L, which cannot be identified by usual techniques. They are albumins and globulins from the identified by usual techniques. They are albumins and globulins from the plasma.plasma.For the protein assay, the urine should be clear and slight acidic. The For the protein assay, the urine should be clear and slight acidic. The turbid urine should be centrifuged or filtrated. If the turbidity persists, turbid urine should be centrifuged or filtrated. If the turbidity persists, prepare a blank of urine and notice the intensification of turbidity.prepare a blank of urine and notice the intensification of turbidity.If the turbidity is due to the presence of lipids (lipiduria) they should be If the turbidity is due to the presence of lipids (lipiduria) they should be extracted with ether.extracted with ether.If it is due to urates the urine should be heated to 60If it is due to urates the urine should be heated to 6000C.C.If the urine is alkaline when voided and collected, the test results become If the urine is alkaline when voided and collected, the test results become uncertain, because the urinary infections (alkaline pH), the urine uncertain, because the urinary infections (alkaline pH), the urine undergoes ammonia fermentation which transforms the albumins in undergoes ammonia fermentation which transforms the albumins in denaturated alkali-albumins which lose some features necessary for the denaturated alkali-albumins which lose some features necessary for the analysis methods. In alkaline urines the phosphates precipitate.analysis methods. In alkaline urines the phosphates precipitate.To acidify the urine add few drops of acetic acid.To acidify the urine add few drops of acetic acid.

PROTEINS IN URINEPROTEINS IN URINE

IDENTIFICATION BY SULFOSALICYLIC ACID TEST.IDENTIFICATION BY SULFOSALICYLIC ACID TEST.Principle: In the presence of proteins in urine, the sulfosalicylic acid Principle: In the presence of proteins in urine, the sulfosalicylic acid

determines the appearance of a turbidity or of a precipitate. (The reaction determines the appearance of a turbidity or of a precipitate. (The reaction is positive for albumoses but by heating the turbidity disappears).is positive for albumoses but by heating the turbidity disappears).

Turbidity allows for detection and rough quantitation of the amount of Turbidity allows for detection and rough quantitation of the amount of proteins present.proteins present.Degree of turbidity:Degree of turbidity:– negative - noncloudinessnegative - noncloudiness– 1+ - distinct cloud, but nogranules or floccules1+ - distinct cloud, but nogranules or floccules– 2+ - distinct cloud plus definite granules2+ - distinct cloud plus definite granules– 3+ - dense cloud with marked flocculation3+ - dense cloud with marked flocculation– 4+ - heavy precipitate to solid coagulum.4+ - heavy precipitate to solid coagulum.

Or the results may be expressed as:Or the results may be expressed as:– albumin absentalbumin absent– very fine cloud of albumins - contain 0.015 g/Lvery fine cloud of albumins - contain 0.015 g/L– fine cloud of albumins - contain 0.02 g/Lfine cloud of albumins - contain 0.02 g/L– abundant precipitate = dosable albuminsabundant precipitate = dosable albumins

False positive reaction may appear after tolbutamide treatment or use of False positive reaction may appear after tolbutamide treatment or use of X-ray contrast media.X-ray contrast media.


Usual techniques may identify more than 0.25 g/L.Usual techniques may identify more than 0.25 g/L.

From the quantitative point of view, the proteinemia may be:From the quantitative point of view, the proteinemia may be:– minimal (less than 0.5 g/day).minimal (less than 0.5 g/day).– moderate (0.5-4 g /day).moderate (0.5-4 g /day).– heavy (more than 4 g/day).heavy (more than 4 g/day).

From the qualitative point of view, proteinuria can be with:From the qualitative point of view, proteinuria can be with:

-- normal proteins (albumins, globulins);normal proteins (albumins, globulins);

-- paraproteins = abnormal proteins as in disglobulinemias such as:paraproteins = abnormal proteins as in disglobulinemias such as:– - multiple myeloma: Bence-Jones proteins which are L chains of - multiple myeloma: Bence-Jones proteins which are L chains of

immunoglobulins, which precipitate at 60immunoglobulins, which precipitate at 6000C and dissolve at 95-100C and dissolve at 95-10000C C (termosoluble proteins) - identified by heat test for Bence-Jones (termosoluble proteins) - identified by heat test for Bence-Jones proteins.proteins.

– -- essential macroglobulinemia.essential macroglobulinemia.– -- Hodgkin’s disease.Hodgkin’s disease.– -- amyloidosis.amyloidosis.


From the clinical point of view, proteinurias are classified in:From the clinical point of view, proteinurias are classified in:

physiologicalphysiological, transient, “functional” - appear in children, young people, post , transient, “functional” - appear in children, young people, post prandial, postural (orthostatic, lordotic), after effort (work, sport, marching), prandial, postural (orthostatic, lordotic), after effort (work, sport, marching), emotional; contains only albumins.emotional; contains only albumins.

-- pathologicalpathological::

-- prerenal: normal or pathological proteins existing in excess in plasma are prerenal: normal or pathological proteins existing in excess in plasma are passing through normal renal filter (incomplete digested proteins absorbed by passing through normal renal filter (incomplete digested proteins absorbed by intestinal mucosa; hepatic synthesis or detoxification is defficient).intestinal mucosa; hepatic synthesis or detoxification is defficient).

-- renal:renal:– oo primary affection of nephron:primary affection of nephron:

oo increased permeability of the glomerul;increased permeability of the glomerul;

oo decreased tubular reabsorption;decreased tubular reabsorption;

oo hypersecretion in renal tubules.hypersecretion in renal tubules.

– oo secondary affecting the nephron:secondary affecting the nephron:oo heart failure;heart failure;

oo thrombosis of cava vein; renal veins;thrombosis of cava vein; renal veins;

oo feochromocytoma.feochromocytoma.

-- posterenal = nephrourologic: urinary tract affections associated with leukocyturia posterenal = nephrourologic: urinary tract affections associated with leukocyturia and epythelial cell as in bleeding (stones, tumours, tuberculosis); inflammation.and epythelial cell as in bleeding (stones, tumours, tuberculosis); inflammation.

NONPROTEIN NITROGENOUS COMPOUNDSNONPROTEIN NITROGENOUS COMPOUNDS CREATINE AND CREATININE CREATINE AND CREATININE

Creatine (methylguanidin acetic acid) is a nonprotein nitrogen Creatine (methylguanidin acetic acid) is a nonprotein nitrogen constituent synthesized in the kidney and liver out of constituent synthesized in the kidney and liver out of arginine, glycine and methionine. It is transported to the arginine, glycine and methionine. It is transported to the tissues, especially to the muscles (skeletal muscles tissues, especially to the muscles (skeletal muscles containing 0.5% creatine), where it is phosphorylated and containing 0.5% creatine), where it is phosphorylated and transformed in creatine-phosphate (phospho-creatine), a transformed in creatine-phosphate (phospho-creatine), a macroergic compound.macroergic compound.

ATP is the immediate source of energy for the muscular ATP is the immediate source of energy for the muscular contraction as it is hydrolyzed to ADP. ATP cannot be stored contraction as it is hydrolyzed to ADP. ATP cannot be stored in sufficient quantity to meet the energy demand of intense in sufficient quantity to meet the energy demand of intense muscular activity. muscular activity.

Creatine phosphate, stored in the muscles is used for energetic Creatine phosphate, stored in the muscles is used for energetic purpose: when energy is needed, creatine-phosphate and purpose: when energy is needed, creatine-phosphate and ADP are converted by the catalytic activity of ADP are converted by the catalytic activity of creatinphosphokinase (CK) to creatine and ATP.creatinphosphokinase (CK) to creatine and ATP.

NONPROTEIN NITROGENOUS COMPOUNDSNONPROTEIN NITROGENOUS COMPOUNDS CREATINE AND CREATININECREATINE AND CREATININE

During the muscular activity, the creatine/creatine-phosphate ratio is During the muscular activity, the creatine/creatine-phosphate ratio is increasing, while at rest the ratio is decreasing by the re-synthesis of increasing, while at rest the ratio is decreasing by the re-synthesis of creatine phosphate.creatine phosphate.

In the process, small amounts of creatine are irreversibly converted to In the process, small amounts of creatine are irreversibly converted to creatininecreatinine (the creatine anhydride). The creatine-phosphate loses its (the creatine anhydride). The creatine-phosphate loses its phosphate as phosphate ion, with closure of ring.phosphate as phosphate ion, with closure of ring.

The creatinine is eliminated in urine as a waste product. It appears in the The creatinine is eliminated in urine as a waste product. It appears in the glomerular filtrate and is not reabsorbed by the tubule. Any condition that glomerular filtrate and is not reabsorbed by the tubule. Any condition that reduces the glomerular filtration rate results in a reduced excretion and reduces the glomerular filtration rate results in a reduced excretion and increased plasmatic concentration.increased plasmatic concentration.

Because the excretion rate of creatinine is relatively constant and its Because the excretion rate of creatinine is relatively constant and its production rate is not influenced by the protein catabolism or other production rate is not influenced by the protein catabolism or other external factors the serum creatinine concentration is an indicator of the external factors the serum creatinine concentration is an indicator of the glomerular filtration. However, the kidney has the ability to compensate glomerular filtration. However, the kidney has the ability to compensate the decrease of function, so the serum creatinine concentration is the decrease of function, so the serum creatinine concentration is detectable increased only when more than 50% of the function is lost.detectable increased only when more than 50% of the function is lost.


DOSING SERUM CREATININE BY JAFFE REACTION.DOSING SERUM CREATININE BY JAFFE REACTION.Principle: Creatinine reacts with picric acid (trinitrophenol) in Principle: Creatinine reacts with picric acid (trinitrophenol) in

alkaline solution to form creatinine picrate, an yellow-orange alkaline solution to form creatinine picrate, an yellow-orange adduct (Jaffe pozitive reaction). The intensity of the colour is adduct (Jaffe pozitive reaction). The intensity of the colour is proportional with the creatinine concentration. The extinction proportional with the creatinine concentration. The extinction is measured at 530 nm.is measured at 530 nm.

Diagnostic significance:Diagnostic significance:Reference values:Reference values:The amount of creatinine produced daily is a function of the The amount of creatinine produced daily is a function of the

muscle mass and is not affected by diet, age, sex, exercise. muscle mass and is not affected by diet, age, sex, exercise. It has a constant value for an individual.It has a constant value for an individual.

Adults:Adults: -Men 0.7-1.2 mg/dl (62-106 -Men 0.7-1.2 mg/dl (62-106 mol/L)mol/L) - Women 0.5-1.1 mg/dl (44.2 - 97 - Women 0.5-1.1 mg/dl (44.2 - 97 mol/L).mol/L).Children 0.4-1.0 mg/dl (36-88 Children 0.4-1.0 mg/dl (36-88 mol/L).mol/L).


Pathological significance:Pathological significance:Increase of serum creatinine concentration more than 1.5 mg/dl indicates a Increase of serum creatinine concentration more than 1.5 mg/dl indicates a

renal disfunction. Minor modification may be significant and parallel with renal disfunction. Minor modification may be significant and parallel with the impairment of renal function.the impairment of renal function.

Prerenal causes:Prerenal causes:intense muscular catabolism - muscular distrophy, infections (diphtheria, intense muscular catabolism - muscular distrophy, infections (diphtheria, leptospirosis);leptospirosis);congestive heart failure, shock;congestive heart failure, shock;salt and water depletion (vomiting, diarrhea, gastrointestinal fistulas, excessive salt and water depletion (vomiting, diarrhea, gastrointestinal fistulas, excessive sweating, uncontrolled diabetus mellitus, diabetes insipidus, excessive diuretics sweating, uncontrolled diabetus mellitus, diabetes insipidus, excessive diuretics use).use).

Renal causes:damage of glomeruli, tubules, renal blood vessels, interstitial Renal causes:damage of glomeruli, tubules, renal blood vessels, interstitial tissuetissue

Postrenal causes:obstruction of the urinary tract by prostatic hypertrophy, Postrenal causes:obstruction of the urinary tract by prostatic hypertrophy, neoplasms compressing the ureters calculi blocking the ureters, neoplasms compressing the ureters calculi blocking the ureters, congenital abnormalities of urinary tract.congenital abnormalities of urinary tract.

Even small increase of serum creatinine after renal transplant may be an Even small increase of serum creatinine after renal transplant may be an indication of transplant rejection.indication of transplant rejection.

Decreased values have no clinical significance.Decreased values have no clinical significance.

NONPROTEIN NITROGENOUS COMPOUNDSNONPROTEIN NITROGENOUS COMPOUNDS CREATININE IN URINECREATININE IN URINE

Creatinine is a waste product formed in muscle from high energy storage Creatinine is a waste product formed in muscle from high energy storage compound creatine-phosphate.compound creatine-phosphate.The amount of creatinine excreted daily is a function of the muscle mass The amount of creatinine excreted daily is a function of the muscle mass and is not affected by the diet, age or exercice. and is not affected by the diet, age or exercice. It is 1-2 g/24 hours for an adult. It is 1-2 g/24 hours for an adult. Women excrete less creatinine than men because of their smaller Women excrete less creatinine than men because of their smaller muscle mass.muscle mass.Creatinine appears in the glomerular Creatinine appears in the glomerular filtratefiltrate and is not reabsorbed by the and is not reabsorbed by the tubule. tubule. A small percentage of the creatinine appearing in the urine may be A small percentage of the creatinine appearing in the urine may be derived from tubular derived from tubular secretionsecretion. This is negligible at normal serum levels . This is negligible at normal serum levels of creatinine but becomes larger as the concentration in the serum rises. of creatinine but becomes larger as the concentration in the serum rises. Temporary changes of the blood flow and glomerular filtration are Temporary changes of the blood flow and glomerular filtration are compensated by increase of secreted creatinine. (About 50% of the compensated by increase of secreted creatinine. (About 50% of the kidney function must be lost before a rise in the serum concentration of kidney function must be lost before a rise in the serum concentration of creatinine can be detected).creatinine can be detected).Principle: Creatinine reacts with alkaline picrate to form a red coloured Principle: Creatinine reacts with alkaline picrate to form a red coloured addition product, the extinction of which is measured at 530 nm (Jaffe addition product, the extinction of which is measured at 530 nm (Jaffe reaction).reaction).

CREATININE IN URINECREATININE IN URINE

Creatinine excretion is referred to 24 hours.Creatinine excretion is referred to 24 hours.

0.8 - 1.9 g/24 hours urine (7.1 - 16.8 0.8 - 1.9 g/24 hours urine (7.1 - 16.8 mol/24 hours).mol/24 hours).

It depends upon the muscle mass of the individual so, has to be It depends upon the muscle mass of the individual so, has to be expressed as function of body weight and volume of urine per day.expressed as function of body weight and volume of urine per day.

men 14 - 28 mg/kg/daymen 14 - 28 mg/kg/day

women 11 - 20 mg/kg/daywomen 11 - 20 mg/kg/day

newborn 7 - 12 mg/kg/daynewborn 7 - 12 mg/kg/day

0.1 - 5 years 8 - 22 mg/kg/day0.1 - 5 years 8 - 22 mg/kg/day

10 - 12 years 8 - 30 mg/kg/day10 - 12 years 8 - 30 mg/kg/day

The factor for converting in mmol/kg/day is 0.00884.The factor for converting in mmol/kg/day is 0.00884.

These values do not depend on the volume of urine excreted daily These values do not depend on the volume of urine excreted daily anymore.anymore.

CREATININE IN URINECREATININE IN URINE

Pathological variations:Pathological variations:

-- Increased values:Increased values:

oo hypothyroidismhypothyroidism

oo acromegalyacromegaly

oo diabetes mellitusdiabetes mellitus

-- Decreased values:Decreased values:

oo chronic renal insufficiencychronic renal insufficiency

oo muscular affectionsmuscular affections

oo hyperthyroidismhyperthyroidism

CREATININE CLEARANCECREATININE CLEARANCE..

Clearance test provides an estimate of the amount of plasma that must Clearance test provides an estimate of the amount of plasma that must have flowed through the kidney glomeruli per minute with complete have flowed through the kidney glomeruli per minute with complete removal of its content of creatinine to account for the creatinine per removal of its content of creatinine to account for the creatinine per minute actually appearing in the urine.The test requires the complete minute actually appearing in the urine.The test requires the complete collection of the urine formed in an accurately recorded period of time collection of the urine formed in an accurately recorded period of time (for calculation of the rate of urine flow) and quantitation of the (for calculation of the rate of urine flow) and quantitation of the compound concentration in both serum and urine.compound concentration in both serum and urine.

The creatinine clearance is calculated as:The creatinine clearance is calculated as:

Clearance creatinine = U/S x VClearance creatinine = U/S x V

where:where:

U is the urine concentration of creatinine;U is the urine concentration of creatinine;

S is the serum creatinine concentration, andS is the serum creatinine concentration, and

V is the volume of urine excreted per minute.V is the volume of urine excreted per minute.

U and S are measured in the same units (mg/dl or SI units).U and S are measured in the same units (mg/dl or SI units).

The clearance is expressed in ml/minute and is practically the same as the The clearance is expressed in ml/minute and is practically the same as the glomerular filtration rate.glomerular filtration rate.

CREATININE CLEARANCECREATININE CLEARANCE..

Reference values:Reference values:

men 95 - 140 ml/minutemen 95 - 140 ml/minute

women 90 - 130 ml/minutewomen 90 - 130 ml/minute

over 1.5 years 55 - 85 ml/min (corrected for A).over 1.5 years 55 - 85 ml/min (corrected for A).

Pathological variations:Pathological variations:

-- increased values have no pathological significance (error in collecting increased values have no pathological significance (error in collecting or timing);or timing);

-- decreased value of creatinine clearance is a very sensitive indicator decreased value of creatinine clearance is a very sensitive indicator of a decreased glomerular filtration rate which may be caused by acute of a decreased glomerular filtration rate which may be caused by acute or chronic damage to the glomerulus, reduced blood flow to the or chronic damage to the glomerulus, reduced blood flow to the glomeruli, acute tubular damage.glomeruli, acute tubular damage.

UREAUREA (75% din NPN) (75% din NPN)

Ingested proteins are hydrolyzed to amino acids that can be used for Ingested proteins are hydrolyzed to amino acids that can be used for anabolic or catabolic purposes. Proteins cannot be stored in the body to anabolic or catabolic purposes. Proteins cannot be stored in the body to any appreciable extent. When the intake is in excess of body any appreciable extent. When the intake is in excess of body requirements for the synthesis of the structural and functional requirements for the synthesis of the structural and functional components, the surplus amino acids are catabolyzed for energy components, the surplus amino acids are catabolyzed for energy purposes.purposes.

The The -amino group of the amino acids from the diet or endogenous sources -amino group of the amino acids from the diet or endogenous sources is transformed in ammonia (toxic compound) which, by hepatic is transformed in ammonia (toxic compound) which, by hepatic ureogenesis is detoxified, producing urea. This is the final, nontoxic ureogenesis is detoxified, producing urea. This is the final, nontoxic product of the protein metabolism, eliminated in urine.product of the protein metabolism, eliminated in urine.

The blood urea concentration expresses the equilibrium between the The blood urea concentration expresses the equilibrium between the production and the excretion of urea.production and the excretion of urea.

UREAUREA

DOSING SERUM UREA BY DIACETYL MONOXIME METHOD.DOSING SERUM UREA BY DIACETYL MONOXIME METHOD.

Principle: When a protein-free serum solution is heated with diacetyl Principle: When a protein-free serum solution is heated with diacetyl monoxime (DAMO) in an acid solution containing an oxidizing agent monoxime (DAMO) in an acid solution containing an oxidizing agent (usually Fe(usually Fe3+3+) and thiosemicarbazide as a stabilizer, urea forms an adduct ) and thiosemicarbazide as a stabilizer, urea forms an adduct with diacetyl. The intensity of colour (red) is photometrically estimated.with diacetyl. The intensity of colour (red) is photometrically estimated.

Diagnostical importance:Diagnostical importance:

Reference values: 20-40 mg/dl.Reference values: 20-40 mg/dl.

Physiological variations:Physiological variations:

Higher values exist in men than in women.Higher values exist in men than in women.

The diet rich in proteins, for a prolonged period of time determines values The diet rich in proteins, for a prolonged period of time determines values reaching the superior limit of the normal range (50 mg/dl).reaching the superior limit of the normal range (50 mg/dl).

Low values are noticed during late pregnancy, because the fetus is growing Low values are noticed during late pregnancy, because the fetus is growing rapidly, using maternal amino acids.rapidly, using maternal amino acids.

UREAUREAPathological significance:Pathological significance:Decreased values are not considered, generaly, pathological. Decreased values are not considered, generaly, pathological. They may be present in: They may be present in:

starvation;starvation; increase of plasmatic volume; severe hepatic affections (hepatocytes can not increase of plasmatic volume; severe hepatic affections (hepatocytes can not synthesize urea out of ammonia): hepatic yellow atrophy, hepatic necrosis, intoxications with synthesize urea out of ammonia): hepatic yellow atrophy, hepatic necrosis, intoxications with phosphorus, CClphosphorus, CCl44, chloroform., chloroform.

Increased values may have different causes:Increased values may have different causes:prerenal causes (acting before the glomerular filtration):prerenal causes (acting before the glomerular filtration):

oo reduction of renal blood circulation (shock, depletion of water and salts as in vomiting, diarrhea, reduction of renal blood circulation (shock, depletion of water and salts as in vomiting, diarrhea, excessive sweating, excessive use of diuretics, uncontrolled diabetus mellitus, diabetus excessive sweating, excessive use of diuretics, uncontrolled diabetus mellitus, diabetus insipidus);insipidus);

oo intense protein catabolism (hemorrhages of the digestive tract, with the digestion of intense protein catabolism (hemorrhages of the digestive tract, with the digestion of the blood and absorption of the products, stress, increased secretion or treatment with steroid the blood and absorption of the products, stress, increased secretion or treatment with steroid hormones which increase the mobilization of proteins in energetic purpose).hormones which increase the mobilization of proteins in energetic purpose).

renal causes (affections of glomeruli, tubule, renal blood vessels, interstitial tissues):renal causes (affections of glomeruli, tubule, renal blood vessels, interstitial tissues):OO acute renal insufficiency: glomerulonephritis;acute renal insufficiency: glomerulonephritis; malignant high blood pressure;malignant high blood pressure; nephrotoxic drugs nephrotoxic drugs

and heavy metals intoxication.and heavy metals intoxication.oo chronic renal affections:chronic renal affections: glomerulonephritis;glomerulonephritis; pyelonephritis;pyelonephritis; arteriosclerosis;arteriosclerosis; diabetes mellitus;diabetes mellitus;

amyloidosis;amyloidosis; colagenoses.colagenoses.

postrenal causes (obstruction of urinary tract - ureters, bladder, urethra - which is postrenal causes (obstruction of urinary tract - ureters, bladder, urethra - which is blocking the excretion of urine the urea can diffuse back into the blood):blocking the excretion of urine the urea can diffuse back into the blood):

oo calculi, tumours, inflammation, strictures of ureters, postsurgical;calculi, tumours, inflammation, strictures of ureters, postsurgical; tumours of the tumours of the bladder, calculi;bladder, calculi; prosthatic adenoma.prosthatic adenoma.

UREA IN URINEUREA IN URINE

Urea, the final product of the proteic metabolism, is Urea, the final product of the proteic metabolism, is eliminated in glomerular filtrate in the same concentration as eliminated in glomerular filtrate in the same concentration as in the plasma. A part is reabsorbed while passing through in the plasma. A part is reabsorbed while passing through the renal tubules. In the conditions of a normal renal blood the renal tubules. In the conditions of a normal renal blood flow and normal renal function, approximately 40% of flow and normal renal function, approximately 40% of filtered urea is reabsorbed. When the flow rate is decreased, filtered urea is reabsorbed. When the flow rate is decreased, the actual and relative amount of reabsorbed urea is the actual and relative amount of reabsorbed urea is increased.The concentration of urine urea varies depending increased.The concentration of urine urea varies depending on the high protein diet and the hormonal status on the high protein diet and the hormonal status (hypersecretion or injection of adrenal steroids that result in (hypersecretion or injection of adrenal steroids that result in protein mobilization for energy purposes).protein mobilization for energy purposes).

UREA IN URINEUREA IN URINE

Reference values: 10 - 35 g/24 hours.Reference values: 10 - 35 g/24 hours.Physiological variations: The concentration of urine urea: Physiological variations: The concentration of urine urea:

-- is increased depending on high protein diet and; is increased depending on high protein diet and; -- is decreased in vegetarian diet. It is decreased during late pregnancy,is decreased in vegetarian diet. It is decreased during late pregnancy,

Pathological variations:Pathological variations:-- increased values of urine urea are present: increased values of urine urea are present: – -- in protein hypercatabolism such as during administration of cortisol-like in protein hypercatabolism such as during administration of cortisol-like

steroids; steroids; – -- in stress situations; in stress situations; – -- prerenal, renal snd postrenal factors which increase urea-N; prerenal, renal snd postrenal factors which increase urea-N; – -- intoxications with phosphorus, arsenicum; intoxications with phosphorus, arsenicum; – -- liver diseases.liver diseases.

-- decreased values exist: decreased values exist: – -- in starvation; in starvation; – -- diet grossly deficient in protein; diet grossly deficient in protein; – -- acute and chronic renal failure; acute and chronic renal failure; – -- acute and chronic nephritis; acute and chronic nephritis; – -- toxic nephritis (Pb, Hg); toxic nephritis (Pb, Hg); – -- hepatic failure with important hepatocytolysis (cirrhosis, cancer).hepatic failure with important hepatocytolysis (cirrhosis, cancer).

URIC ACIDURIC ACID

The uric acid is the final product of the catabolism of the nucleic acids in The uric acid is the final product of the catabolism of the nucleic acids in human organism and in higher apes. The nucleic acids may be human organism and in higher apes. The nucleic acids may be exogenous (from the diet) or endogenous (from the distruction of cells).exogenous (from the diet) or endogenous (from the distruction of cells).

Uric acid production (uricopoesis) is performed by the liver, by Uric acid production (uricopoesis) is performed by the liver, by enzymatic oxydation of purines (adenine and guanine).enzymatic oxydation of purines (adenine and guanine).

URIC ACIDURIC ACID

The uric acid is transported in the plasma as sodium urate (saturated The uric acid is transported in the plasma as sodium urate (saturated solution stabilized by the proteins) and excreted in urine by glomerular solution stabilized by the proteins) and excreted in urine by glomerular filtration, partial reabsorption and partial secretion.filtration, partial reabsorption and partial secretion.

Determination of uric acid concentration is not used as a test for the Determination of uric acid concentration is not used as a test for the evaluation of the renal function. Creatinine and urea serve this purpose evaluation of the renal function. Creatinine and urea serve this purpose much better. Urea values are still influenced by the diet, protein much better. Urea values are still influenced by the diet, protein catabolism and hormonal status. The variations of the uric acid are catabolism and hormonal status. The variations of the uric acid are parallel with those of the other two nitrogen nonprotein compounds, being parallel with those of the other two nitrogen nonprotein compounds, being increased when it is improper formation or excretion of urine, irrespective increased when it is improper formation or excretion of urine, irrespective of the cause.of the cause.The main value of the serum uric acid test is in the diagnosis of gout or for The main value of the serum uric acid test is in the diagnosis of gout or for following the treatment of patients with this disease, identifying a large-scale following the treatment of patients with this disease, identifying a large-scale breakdown of nucleic acids (toxemia of pregnancy, massive irradiation for breakdown of nucleic acids (toxemia of pregnancy, massive irradiation for tumours, administration of cytotoxic agents in malignancies).tumours, administration of cytotoxic agents in malignancies).

Hyperuricemia corresponds to the clinical aspect of gout which is characterized by Hyperuricemia corresponds to the clinical aspect of gout which is characterized by the precipitation of uric acid crystals in tissues and joints (big toe) representing a the precipitation of uric acid crystals in tissues and joints (big toe) representing a great danger because of the deposition of urate in the kidneys.great danger because of the deposition of urate in the kidneys.

URIC ACIDURIC ACIDDOSING BY REDUCTION OF PHOSPHOTUNGSTATE.DOSING BY REDUCTION OF PHOSPHOTUNGSTATE.Principle: In alkaline solution, urate is oxidized to allantoin by phosphotungstate and Principle: In alkaline solution, urate is oxidized to allantoin by phosphotungstate and

phosphotungstate complex is reduced to form a blue complex. The extinction is phosphotungstate complex is reduced to form a blue complex. The extinction is measured at 710 nm.measured at 710 nm.

Diagnostic importance:Diagnostic importance:Reference values:Reference values:

3 - 7 mg/dl (0.178 - 0.420 mm0l/L).3 - 7 mg/dl (0.178 - 0.420 mm0l/L).Physiological variations exist dependent on varied factors:Physiological variations exist dependent on varied factors:

1. sex:1. sex:-- men 3.5 - 7.5 mg/dl (0.210 - 0.445 mmol/L).men 3.5 - 7.5 mg/dl (0.210 - 0.445 mmol/L).-- women 2.5 - 6.5 mg/dl (0.150 - 0.390 mmol/L).women 2.5 - 6.5 mg/dl (0.150 - 0.390 mmol/L).-- at menopause, the values are lower than before, then they become equal to at menopause, the values are lower than before, then they become equal to those of men.those of men.2. age:2. age:-- newborns have higher values than adults.newborns have higher values than adults.-- children have lower values than adults.children have lower values than adults.3. diet rich in purines (viscera, meat of young animals, cocoa, chocholate, coffee, 3. diet rich in purines (viscera, meat of young animals, cocoa, chocholate, coffee, spinach, asparagus, cauliflower, beans, lentil) increase the values of uricemia;spinach, asparagus, cauliflower, beans, lentil) increase the values of uricemia;4. exercise.4. exercise.

URIC ACIDURIC ACID

Pathological significance:Pathological significance:1. Increased values:1. Increased values:-- high production:high production:– -- primary gout;primary gout;– -- leukemia, hemolytic anemia, polycytemia;leukemia, hemolytic anemia, polycytemia;– -- irradiation of tumours;irradiation of tumours;– -- cytolytic treatment for malignancies.cytolytic treatment for malignancies.

-- impaired excretion:impaired excretion: - obstruction on the urinary tract;- obstruction on the urinary tract; - thiazide diuretics treatment;- thiazide diuretics treatment; - aspirin less than 2 g/day.- aspirin less than 2 g/day.

2. Decreased values:2. Decreased values:-- decreased production: decreased production: - allopurinol (inhibitor of xantin oxidase);- allopurinol (inhibitor of xantin oxidase);

-- increased excretion:increased excretion: - uricouric drugs (probenecid, sulfinpyranoze), aspirin more than 4 g/day;- uricouric drugs (probenecid, sulfinpyranoze), aspirin more than 4 g/day; - ACTH, corticosteroid hormones, estrogens, anticoagulant treatment.- ACTH, corticosteroid hormones, estrogens, anticoagulant treatment.

URIC ACID IN URINEURIC ACID IN URINE

Uric acid, the final product of the catabolism of the purine nitrogenous Uric acid, the final product of the catabolism of the purine nitrogenous bases (adenine, guanine), is excreted in urine by filtration, reabsorption bases (adenine, guanine), is excreted in urine by filtration, reabsorption and secretion. It is poorly soluble in water. When the urate concentration and secretion. It is poorly soluble in water. When the urate concentration in urine is increased, the urate precipitates around some nuclei formed in urine is increased, the urate precipitates around some nuclei formed of clots, fibrin, bacteria, sloughed epithelial cells forming insoluble calculi of clots, fibrin, bacteria, sloughed epithelial cells forming insoluble calculi (stones) in the kidney or urinary tract. Calculi may be formed in patients (stones) in the kidney or urinary tract. Calculi may be formed in patients with normal uricemia but increased level of uric acid excretion.with normal uricemia but increased level of uric acid excretion.

Reference values:Reference values:

adults 0.25 - 0.80 g/24 hours (1.48 - 4.76 mmol/24 hours)adults 0.25 - 0.80 g/24 hours (1.48 - 4.76 mmol/24 hours)

children 3.50 - 10.00 mg/kg/24 hourschildren 3.50 - 10.00 mg/kg/24 hours

under 1 year 20.00 - 30.00 mg/kg/24 hoursunder 1 year 20.00 - 30.00 mg/kg/24 hours

Physiological variations:Physiological variations:

The concentration of uric acid in the urine is influenced by the purine The concentration of uric acid in the urine is influenced by the purine content of the diet. High purine diet (meat, organs) determines the content of the diet. High purine diet (meat, organs) determines the increase of uricemia and uric acid excretion in urine (1 g/24 hours). Low increase of uricemia and uric acid excretion in urine (1 g/24 hours). Low purine diet determine a decreased excretion of uric acid.purine diet determine a decreased excretion of uric acid.

URIC ACID IN URINEURIC ACID IN URINE

Pathological significance:Pathological significance:The amount of the uric acid and the pH of urine are the factors which can The amount of the uric acid and the pH of urine are the factors which can determine the formation of the urate calculi, by the precipitation of the acidic determine the formation of the urate calculi, by the precipitation of the acidic sodium urates in the acidic pH determined by the animal origin food (milk sodium urates in the acidic pH determined by the animal origin food (milk excluded), tuberculous infection, diverse drugs.excluded), tuberculous infection, diverse drugs.

-- Increased values exist in: Increased values exist in: oo gout (podagra); gout (podagra); oo diseases with intense cytolysis (leukemia, lymphomatosis, polycytemia, diseases with intense cytolysis (leukemia, lymphomatosis, polycytemia, hemolytic anemia); hemolytic anemia); oo administration of drugs (probenecid,sulfapyrazone); administration of drugs (probenecid,sulfapyrazone); oo administration of aspirin in higher dose than 4 g/day; corticosteroid and administration of aspirin in higher dose than 4 g/day; corticosteroid and estrogen hormones, ACTH.estrogen hormones, ACTH.

-- Decreased values exist in: Decreased values exist in: oo renal failure; renal failure; oo ketoacidosis (diabetes mellitus, starvation); ketoacidosis (diabetes mellitus, starvation); oo lactic acidosis; lactic acidosis; oo tiazidic diuretics; tiazidic diuretics; oo administration of aspirin more than 2 g/day; administration of aspirin more than 2 g/day; oo alcohol ingestion; alcohol ingestion; o before gout crisisbefore gout crisis..

clinical biochemistry 3 biochemical investigation of kidneys function

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