Endogenous bile acid tolerance test for liver function.

Fasting and postprandial (stimulated) serum conjugated bile acids (CBA) were measured by a solid-phase radioimmunoassay in 329 patients undergoing liver biopsy, and the results were analyzed for 231 who fitted into 10 diagnostic categories. In healthy volunteers the mean fasting CBA of 1.8 +/- 0.7 mumol/liter rose to 3.0 +/- 0.8 mumol/liter postprandially. In patients mean fasting and stimulated CBA were only significantly raised in moderate to severe chronic and acute liver disease. Diagnostic sensitivity was poor in mild liver disease. Individuals with normal results were found in 8 of 11 disease categories. The ratio of stimulated to fasting CBA expressed in a stimulation quotient did not rise in more advanced liver disease. These findings are best explained by a constant fractional clearance of bile acids by the liver. We conclude that the serum conjugated bile acid determination as a test of liver cell function is not sensitive enough to identify all cases of biopsy-proven liver disease.