Bilirubin Total Direct Indirect

These assays are commonly used tests to assess liver function. Daily production of unconjugated bilirubin is mainly from senescent erythrocytes. The half-life of unconjugated bilirubin is <5 minutes. UDP - GlucuronyI transferase catalyzes rapid conjugation of bilirubin to liver; conjugated bilirubin is excreted in bile and is essentially absent from the blood of the normal individuals. Delta bilirubin (bili protein) is produced by reaction of conjugated bilirubin with albumin, and its half-life is 17-20 days. Bilirubin is typically measured in two assays for “total” and “direct”; subtracting direct form total gives “indirect bilirubin”. The direct bilirubin measures the majority of delta and conjugated bilirubin and a small percentage of unconjugated bilirubin. ·

Normal range:Age dependent (see Table 2-12)

Use ·Assessing liver function· Evaluating a wide range of diseases affecting the production, uptake, storage, metabolism, or excretion of bilirubin · Monitoring the effificacy of neonatal phototherapy.