Bilirubin, Direct

Alternative Names
  • Direct Bilirubin

Test Code: 4546

CPT: 82248
Tests Included Direct Bilirubin
Use Bilirubin is an end product of hemoglobin catabolism. It is conjugated with glucuronic acid in the liver, and the conjugated form is cleared from the circulation by excretion in the bile. Both conjugated (direct) and unconjugated (indirect) forms of bilirubin circulate loosely bound to albumin.
Clinical Utility The assessment of direct bilirubin is helpful in the determination of hepatic disorders. The increase in the total bilirubin associated with obstructive jaundice is primarily due to the direct fraction. Both direct and indirect bilirubin are increased in the serum with hepatitis. In the newborn patient with hemolytic jaundice and neonatal jaundice, the increase in the total bilirubin is primarily due to the indirect bilirubin fraction. This jaundice may be caused by Rh, ABO, or other blood group incompatibilities, by hepatic immaturity, or by hereditary defects in bilirubin conjugation.
Intended Patient Population 18+ and Older Adult Males & Females
Patient Preparation None Specified
Sample Serum, Plasma
Tube Red, Green, Tiger
Volume 4mL Whole Blood (1mL Serum/Plasma)
Min Sample Volume 0.5 mLs
Reference Ranges M & F ≥ 18 yrs old; 0.0-0.2 mg/dL
Analytical Measurement Range 0.0-10.0 mg/dL
Critical Values ≥4.0 mg/dL
Units mg/dL
Test Methodology Diazonium Salt, DPD
Test Turnaround Time 2 Days
Limitations Not suitable for neonatal testing
Shipping Requirements Refrigerated
Specimen Stability N/A
Reject Criteria Gross Hemolysis, Gross Lipemia
Excess Light Exposure
Laboratory Developed Test (LDT) Yes
CMS Guidance None
  1. Tietz, N.W.(ed), Fundamentals of Clinical Chemistry, 3rd Edition, W.B. Saunders, 1987.
  2. Van den Bergh, A. and Mueller, P., Biochem Z, 77: 90, 1916.

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