Bilirubin (Total)

Overview

Total bilirubin measures the combined levels of unconjugated (indirect) and conjugated (direct) bilirubin in the blood, a byproduct of red blood cell breakdown processed by the liver. It reflects liver function, bile flow, and hemolysis rates. Elevated levels may indicate liver diseases like hepatitis or cirrhosis, biliary obstruction, or hemolytic anemia, while low levels are rarely clinically significant. Clinically, it helps diagnose jaundice causes and monitor liver health.[ from prior][rupahealth]​

Clinical Use Cases

  • Evaluating jaundice in newborns and adults.
  • Diagnosing liver diseases (hepatitis, cirrhosis).
  • Assessing hemolytic anemias.
  • Monitoring biliary obstruction or cholestasis.

Specimen Types

  • Serum.
  • Plasma (heparin or EDTA).
  • Whole blood (point-of-care).

Measurement Methods

  • Diazo method (van den Bergh reaction).
  • Spectrophotometry.
  • Enzymatic assays.

Test Preparation and Influencing Factors

  • No fasting required, but fasting may lower levels.
  • Hemolysis or lipemia interferes with results.
  • Medications (rifampin, probenecid) affect levels.
  • Neonates have higher physiological levels; diurnal variation exists.

Synonyms

  • Total serum bilirubin.
  • TSB.
  • TBIL.

Further Reading