To test whether hepatotoxicity occurring in National Cooperative
Gallstone Study patients was caused by a toxic effect of
chenodiol per se or of
lithocholate caused by defective sulfation, bile samples were analyzed using a new high-performance liquid chromatography method that measures the proportions of the four individual
lithocholate amidates (sulfated and unsulfated
lithocholylglycine and
lithocholyltaurine) and all common
bile acid amidates. Samples were obtained from National Cooperative
Gallstone Study patients (n = 17) with abnormal light microscopic liver biopsy results or major
aminotransferase elevations and from a matched control group of patients (n = 14) who received similar
chenodiol doses but had no evidence of liver injury. Bile samples from 45 healthy subjects were also analyzed. The analytical method was validated by showing that the percentage of
chenodiol and cholic and
deoxycholic acid obtained by high-performance liquid chromatography correlated highly (r greater than 0.94) with previous gas-liquid chromatography analyses of these samples by the National Cooperative
Gallstone Study Reference Laboratory. No significant differences were seen between
gallstone patients with and without evidence of liver injury for percent total
lithocholate amidates, percent sulfated or unsulfated
lithocholate amidates or percent
chenodiol amidates.
Lithocholate was partially sulfated in all bile samples (52% +/- 17% [mean +/- S.D., n = 50]), but the extent of sulfation varied widely between and within patients during the course of
therapy. Mean values of healthy subjects were similar and also showed a wide range in the extent of
lithocholate sulfation. It is concluded that (a) liver injury caused by these doses of
chenodiol could not be attributed to the accumulation of unsulfated
lithocholate per se in circulating
bile acids; (b) liver injury appeared to be, directly or indirectly, caused by enrichment in circulating
bile acids with
chenodiol or
chenodiol together with
lithocholate, suggesting that the hepatocytes of those patients with hepatotoxicity were injured by the change induced in
bile-acid metabolism by the feeding of
chenodiol; and (c) about half of
lithocholate amidates in bile samples were sulfated, but the extent of sulfation was highly variable both in
gallstone patients and healthy subjects.