Bilirubin

Alternative names:

conjugated bilirubin; direct bilirubin; indirect bilirubin; total bilirubin; unconjugated bilirubin

Normal values:

• direct bilirubin: 0 to 0.3 mg/dl
• total bilirubin: 0.3 to 1.9 mg/dl

Note: mg/dl = milligrams per deciliter

What abnormal results mean:

Jaundice can occur if bilirubin builds up either because red blood cells are being broken down too fast for the liver, because of disease in the liver, or blockage of the bile ducts. Jaundice is the discoloration of skin and sclera of the eye, which occurs when bilirubin accumulates in the blood at a level greater than approximately 2.5 mg/dl.

If the bile ducts are obstructed, direct bilirubin will build up, causing some of it to escape from the liver and end up in the blood. If the levels are high enough, some of it will appear in the urine. Only direct bilirubin appears in the urine. Increased direct bilirubin usually means that the biliary (liver secretion) ducts are obstructed.

Increased indirect or total bilirubin may indicate:

• erythroblastosis fetalis
• Gilbert's anomaly
• hemolytic anemia
• hemolytic disease of the newborn
• physiological jaundice (normal in newborns)
• sickle cell anemia
• transfusion reaction
• pernicious anemia
• resolution of a large hematoma

Increased direct bilirubin may indicate:

• bile duct obstruction
• cirrhosis
• Crigler-Najjar syndrome (very rare)
• Dubin-Johnson syndrome (very rare)
• hepatitis

Additional conditions under which the test may be performed:

• biliary stricture
• cholangiocarcinoma
• cholangitis
• choledocholithiasis
• hemolytic anemia due to G6PD deficiency
• hepatic Encephalopathy
• idiopathic aplastic anemia
• idiopathic autoimmune hemolytic anemia
• immune hemolytic anemia
• secondary aplastic anemia
• drug-induced immune hemolytic anemia
• thrombotic thrombocytopenic purpura
• Wilson's disease