Interpretation of Plasma on Studies With

Abstract

The plasma unconjugated bilirubin concentration (Br) is related to the bilirubin production rate (BRP) and hepatic bilirubin clearance (C_Br) in the following manner: Br = BRP ÷ C_Br. The distribution for Br in the normal population was calculated from this relationship, using normal values of BRP and C_Brmeasured with labeled bilirubin. The results indicate that any individual with a Br exceeding 1.0 mg/100 ml (99% level) should be suspected of having abnormal hepatic function or bilirubin overproduction or both. A Br greater than 3.5 mg/100 ml usually indicates abnormal hepatic function, regardless of the BRP. A change in Br means that either bilirubin production or hepatic function has been altered, even if Br remains within the normal range.