Direct Bilirubin

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Latest Edit: Hector 2014-03-24 (EDT)

See Also Lab Tests

Direct bilirubin refers to the inidrect or unconjugated bilirubin that has been conjugated with a number of different molecules and then excreted in the bile. Increased direct or conjugated bilirubin is usually inidcative of a dysfunction or blockage in the liver, gallbladder, or biliary tree.[1],[2]

Patient Preparation

  • Factors which can cause increased levels
  • Prolonged fasting
  • Factors which can cause decreased levels
  • Exposure of sample to sunlight or bright artificial light at room temperature, high fat meal, air bubble and shaking of sample

Clinical Implications

Ranges: The following are the reference ranges for this lab. However, lab ranges can vary by laboratory and country. [2]

Standard U.S. Units Standard International Units
Conventional Laboratory Range 0-0.2 mg/dL 0-3.4 umol/L
Optimal Range 0-0.2 mg/dL 0-3.4 umol/L
Alarm Ranges > 0.8 mg/dL > 13.7 umol/L

High levels indicate:

  • Biliary tract obstruction (due to liver dysfunction)
  • Biliary duct obstruction (usually extra hepatic) / biliary calculi

Low levels indicate:

  • low levels of direct bilirubin have no clinical significance

Associated Tests

References

  1. Pagana Kathleen D, Pagana Timothy J, (1998) Mosby's Manual of Diagnostic and Laboratory Tests, Mosby, Inc
  2. 2.0 2.1 Weatherby Dicken, Ferguson Scott (2002) Blood Chemistry and CBC Analysis: Clinical Laboratory Testing from a Functional Perspective, Bear Mountain Cite error: Invalid <ref> tag; name "weatherby" defined multiple times with different content