Quantitative Determination of Serum Bile Acids using a 7α-Hydroxysteroid Dehydrogenase

Abstract

A crude 7α-hydroxysteroid dehydrogenase isolated from P. testosteroni requires NADP specifically and provides a simple and specific means for the determination of 7α-hydroxy bile acids and their conjugates. A specific and reliable enzymatic-fluorimetric method for the quantitative measurement of the primary bile acids in serum is described. Overall recovery from normal and jaundiced serum averaged 85%. The mean concentration of serum 7α-hydroxy bile acids in fasting, healthy subjects was 2.5 μmoles/l (S.D. 1.45 and range 1.2-6.3), averaging 73% (S.D. 11.5) of the total, measured as the 3α-hydroxy bile acid concentration. In parenchymatous liver disease and cholestatic hepatobiliary disorders, the proportion of 7α-hydroxy bile acids was significantly increased, mean 92.5% (S.D. 6.6) (p<0.001).