Bilirubin, Direct
Use
Evaluate liver and biliary disease. Increased direct bilirubin occurs with biliary diseases, including both intrahepatic and extrahepatic lesions. Hepatocellular causes of elevation include hepatitis, cirrhosis, and advanced neoplastic states. Increased with cholestatic drug reactions, Dubin-Johnson syndrome, and Rotor syndrome. In the latter two syndromes, the level is usually <5 mg/dL.
Special Instructions
Measurement of direct bilirubin is usually not necessary when the total bilirubin is less than 1.2 mg/dL. Direct bilirubin is the water-soluble fraction and may become positive in urine when increased in serum. The collection instructions require separation of serum or plasma from cells within 45 minutes of collection.
Limitations
Theoretically, direct bilirubin should not be increased in hemolytic anemias, where bilirubin increase should be in the indirect fraction, absent complications. However, practice may show a slight increase in the direct fraction in hemolytic anemia without proven complications. Some methods can falsely elevate direct bilirubin due to sodium nitrite concentrations converting unconjugated bilirubin to conjugated bilirubin, affecting accuracy.
Methodology
Automated Analyzer (Colorimetric)
Biomarkers
LOINC Codes
- 1968-7
- 1968-7
Result Turnaround Time
1 day
Related Documents
For more information, please review the documents below
Specimen
Serum
Volume
1 mL
Minimum Volume
0.7 mL
Container
Red-top tube, gel-barrier tube, or green-top (lithium heparin) tube
Collection Instructions
Separate serum or plasma from cells within 45 minutes of collection.
Storage Instructions
Refrigerate
Causes for Rejection
Gross hemolysis; improper labeling; gross lipemia
Stability Requirements
| Temperature | Period |
|---|---|
| Room Temperature | 2 days |
| Refrigerated | 3 days |
| Frozen | 14 days |