Clinical Significance

   It is useful for

       Assessing liver function

       Evaluating a wide range of diseases affecting the production, uptake, storage, metabolism, or excretion of bilirubin

       Monitoring the efficacy of neonatal phototherapy

Specimen

   Serum

Stability

   Refrigerated (preferred) : 7 days (LIGHT PROTECTED specimen container)

   Frozen : 30 days (LIGHT PROTECTED specimen container)

   Ambient : 24 hours (LIGHT PROTECTED specimen container)

Reference Range

   < 1.23 µmol/L

Interpretation

   When any portion of the biliary tree becomes blocked, bilirubin levels will increase. Physiologic jaundice should resolve in 5 to 10 days in full-term infants and by 14 days in preterm infants.

Limitation

   Compounds that compete for binding sites on serum albumin contribute to lower serum bilirubin levels (eg, penicillin, sulfisoxazole, acetylsalicylic acid). Results from certain multiple myeloma patient specimens may show a positive bias. Not all multiple myeloma patients show the bias and the severity of the bias may vary between patients. In very rare cases, increased gamma globulin levels, in particular type IgM (Waldenstroms macroglobulinemia, may cause unreliable results.