Analysis of response to ursodeoxycholic acid for gallstone dissolution

20 patients with radiolucent gallbladder stones were reviewed after 6 months' treatment with ursodeoxycholic acid (UDCA) at a dose of either 500 or 1,000 mg daily. Successful treatment could not be predicted from the patients' characteristics, nor from stone size or pre-treatment biliary lipid analysis. During treatment the bile in patients who responded to UDCA differed from bile in those who did not: mean cholesterol content was lower in responders (4.1 +/- 0.6 vs. 5.7 +/- 0.5 mol%, p less than 0.025) as was the lithogenic index (0.57 +/- 0.06 vs. 0.81 +/- 0.06, p less than 0.005) and the mean UDCA-corrected lithogenic index (0.79 +/- 0.10 vs. 1.04 +/- 0.07, p less than 0.05). However, the individual response could not be predicted from biliary lipid analysis during treatment.