What does the Total Bilirubin test measure?

Why is Total Bilirubin measured?

Hyperbilirubinaemia (>1.2 mg/dL) manifests as jaundice when total bilirubin exceeds approximately 2.5 mg/dL. Predominantly unconjugated elevation points to haemolysis, Gilbert syndrome, or Crigler–Najjar syndrome; conjugated (direct) hyperbilirubinaemia indicates hepatocellular injury or cholestasis. Total bilirubin is interpreted alongside direct bilirubin, ALT, AST, and ALP to classify the pattern of liver or biliary disease.

Reference ranges

Standard reference

Approximately 0.1–1.2 mg/dL; varies by laboratory and Gilbert syndrome prevalence.

Functional medicine optimal

Within laboratory limits; mild isolated elevation of unconjugated bilirubin is often benign (Gilbert syndrome), but new or progressive hyperbilirubinaemia warrants thorough evaluation.

Units

µmol/L, mg/dL

Reference ranges vary by laboratory and assay platform. Interpret in context of the issuing laboratory's stated range.