Red blood cell (RBC) hemolysis from a variety of causes
Obstruction of the biliary tract from any of the several possibilities
Intrahepatic biliary diseases: primary biliary cirrhosis (PBC), primary sclerosing cholangitis (PSC)
Hereditary conjugated hyperbilirubinemias: Dubin-Johnson syndrome, Rotor syndrome
Hereditary unconjugated hyperbilirubinemias: Criggler-Najjar syndrome type I, Criggler-Najjar syndrome type II, Gilbert syndrome
Suggested Additional Lab Testing
Tests to identify common causes of elevated bilirubin, such as hepatitis, are useful.
Perform tests for liver function in addition to total and unconjugated bilirubin, including AST, ALT, alkaline phosphatase, albumin, GGT, or 5´-nucleotidase, among others.
Tests to rule out RBC hemolysis as a cause for increased bilirubin are important.
Very high alkaline phosphatase and GGT or 5´-nucleotidase, with smaller elevations in AST and ALT
Positive anti-mitochondrial antibody test in 95% of PBC patientts
Alkaline phosphatase, GGT, 5´-nucleotidase, ALT, and AST elevations similar to those found in PBC
Total bilirubin and unconjugated bilirubin usually 2-5 mg/dL, with at least 50% of the bilirubin conjugated
Coproporphyrin excretion in urine increased 2.5- to 5-fold over normal healthy controls
Criggler-Najjar syndrome type I
Markedly elevated total bilirubin (15 to >50 mg/dL) with essentially all of the bilirubin unconjugated
Liver function tests within the normal range
Total bilirubin values for type II typically lower than Criggler-Najjar type I; type II, the bilirubin is almost all unconjugated, as in the type I disorder.
Total bilirubin concentration usually less than 3 mg/dL; essentially all is unconjugated with normal liver function tests
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