What Is Bilirubin in a Blood Test?

Bilirubin is a yellow pigment from red blood cell breakdown, processed by the liver and excreted in bile. Elevated levels cause jaundice.

Normal Range

• Total: 0.3–1.2 mg/dL
• Direct (conjugated): 0.0–0.3 mg/dL
• Above 2.5 mg/dL = jaundice visible

High Indirect Bilirubin

• Hemolysis — excessive red cell destruction
• Gilbert syndrome — benign genetic condition (5–10% of population)
• Ineffective erythropoiesis

High Direct Bilirubin

• Bile duct obstruction — gallstones, tumors
• Liver disease — hepatitis, cirrhosis
• Drug-induced cholestasis

Clinical Patterns

• Isolated mild indirect elevation = likely Gilbert syndrome (benign)
• Marked elevation with dark urine, pale stools = bile duct obstruction (urgent)
• Elevated with liver enzymes = hepatitis or liver injury