Evaluation of two enzymatic methods of determining unsulphated serum bile acids.

Two enzymatic methods of determining unsulphated 3 alpha-hydroxylated and 7 alpha-hydroxylated bile acids, respectively, were evaluated. Both methods are based on a coupled enzyme reaction involving a coloured redox indicator and absorbance measurement as the final step. Recovery and specificity were tested on human serum pools containing different bile acids added in various amounts, and by comparison of the results with those obtained by gas-liquid chromatography after group separation of bile acids from patient sera. Results from the two enzymatic methods were also compared with those determined with radioimmunoassay on a large number of patient sera. The results indicate that the enzymatic methods are useful for serum bile acid screening but more sensitive methods are necessary for investigations within the normal range.