Evaluation of enzymic and radioimmunoassay methods for measuring serum bile acids

Serum bile acids were measured in control subjects and in 23 patients with cirrhosis or cholestasis using an enzymic method which measures total non-sulphated bile acids and 2 commercially available radioimmunoassay methods which measure cholylglycine (CG) and sulpholithocholylglycine (SLCG) respectively. All 3 methods gave abnormal values in patients with cholestasis. In cirrhosis the CG method gave abnormal values more often than the enzymic method. The SLCG method was much less sensitive. Measurement of CG in 2 postprandial samples per patient detected only one patient with normal fasting but abnormal postprandial levels. Analysis of samples by gas liquid chromatography (GLC) showed that the enzymic and CG methods gave a good estimation of total non-sulphated bile acids and cholic acid respectively. Values determined by the SLCG method were much higher than the equivalent GLC values. The CG method is faster than the enzymic method and is less expensive provided sample are analysed in sufficiently large batches.