Description

The ratio of direct to total serum bilirubin can help in predicting the cause of jaundice. The total serum bilirubin must exceed 2.5 mg/dl to produce clinical jaundice.


 

direct bilirubin-to-total bilirubin ratio =

= ((serum direct bilirubin) / (serum total bilirubin))

 

Interpretation

 

Ratio

Differential Diagnosis

< 20%

constitutional hyperbilirubinemia (Gilbert's, Crigler-Najjar, etc.)

20-40%

hepatocellular disease more likely than extrahepatic obstruction

40-60%

may be either hepatocellular disease or extrahepatic obstruction

> 60%

extrahepatic obstruction more likely than hepatocellular disease

 

 


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