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Bilirubin is the product of red blood cell breakdown.
The bilirubin initially is "unconjugated," and travels through
the bloodstream to the liver. In the liver, it is metabolized to
"conjugated" bilirubin, and excreted in the liver bile.
An increase in breakdown of red cells (such as in hemolysis) leads to an
increase in unconjugated bilirubin. Liver disease leads to loss of
conjugated bilirubin into the bloodstream and a measurable increase.
Total bilirubin is a combination of both conjugated and unconjugated
bilirubin.
Elevations in Unconjugated Bilirubin are found in:
- Hemolysis
- Trauma leading to a hematoma
- Hemorrhagic pulmonary infarcts
Elevations in Conjugated Bilirubin are found in:
- Pancreatic cancer
- Obstruction of the bile duct
Elevations in both Unconjugated and Conjugated Bilirubin are found in:
- Hepatitis
- Cirrhosis
- Liver cancer
- Drug-induced cholestasis
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Normal Values*
| Total |
0.2-1.0 mg/dl |
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Unconjugated ("Indirect") |
0.2-0.8 mg/dl |
| Conjugated ("Direct") |
0-0.2 mg/dl |
*These are general values taken from a variety of
sources. The actual normal values may vary from lab to lab and from one
type of testing protocol to another.
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