liver function bilirubin fractions of bilirubin in serum

liver function (bilirubin)

fractions of bilirubin in serum: -Unconjugated bilirubin (α –bilirubin). -monoconjugated bilirubin (β –bilirubin) -Diconjugated bilirubin (γ –bilirubin) -A tightly bound fraction of bilirubin to protein which is known as (δ- bilirubin

Clinical Significance a-Pre-hepatic hyperbilirubinemia b-Hepatocellular hyperbilirubinemia c-Cholestatic Hyperbilirubinemia

Pre-hepatic hyperbilirubinemia -Overproduction of bilirubin occurs in all forms of hemolytic anemias and in hemolytic disease of the newborn due to rhesus incompatibility,

Hepatocellular hyperbilirubinemia Decreased hepatic uptake of bilirubin : . , in Gilbert's syndrome, hepatitis and cirrhosis. -Impaired conjugation of bilirubin : . generalized hepatocellular damage due to viral hepatitis and cirrhosis congenital deficiency of conjugating enzyme (Crigler-Najjar syndromes). -Impaired secretion of conjugated bilirubin into bile : in conjugated hyperbilirubinemia as in patients with hepatocellular damage

Cholestatic Hyperbilirubinemia -Intra-hepatic cholestasis: It occurs in acute hepatocellular damage (acute hepatitis), cirrhosis and hepatic carcinoma. -Extra-hepatic cholestasis: This is caused by mechanical obstruction of the biliary tree due to gallstones, cancer head of the pancreas or carcinoma of the biliary tree

Specimen -Serum, plasma or urine may be used. -Hemolysis should be avoided, since it produces falsely low values with diazo methods. -Specimens should be protected from direct exposure to light, because both conjugated and unconjugated bilirubin are photo-oxidized when exposed to light

Analytical Methods -The most widely used methods for bilirubin measurement are photometric methods based on the diazo reaction

Reference Intervals Serum Bilirubin mg/d. L Total bilirubin 0. 3 – 1. 2 Conjugated bilirubin 0. 0 – 0. 2 The upper critical limit of total serum bilirubin in newborns is 15 mg/d. L