The effect of ursodeoxycholic acid therapy on gallstone formation in the morbidly obese during rapid weight loss

Abstract

Obesity is a significant risk factor for cholesterol gallstone formation, particularly when patients are morbidly obese and rapidly losing weight. Our objective, in a double-blind, placebo-driven trial of ursodeoxycholic acid, was to study the prevention of gallstone development in 29 morbidly obese subjects after bariatric surgery. These subjects included 20 women and nine men, ages 43 +/- 7.3 yr, weight 142.5 +/- 31 kg (mean +/- SD), representing 224% +/- 28.2% of their ideal body weight. Gallbladders were free of stones according to preoperative ultrasound and palpation at surgery. Microscopy of aspirated gallbladder bile revealed cholesterol crystals present in only one patient. After recovery from vertical-band gastroplasty, 13 patients received ursodeoxycholic acid 1000 mg/day. Ten patients completed the 3-month study: two were noncompliant, one experienced heartburn. Fourteen of 16 subjects on matching placebo also were compliant; two were not. There were no differences in clinical characteristics or bile composition between these two groups on entry into the study. The cholesterol saturation index in these obese patients at 1.62 +/- 0.46 was definitely supersaturated, and higher than that in 10 non-obese patients without stones (0.96 +/- 0.29) or 10 with pigment stones (1.01 +/- 0.28) (p < 0.05). At 3 months, the two obese groups had similar weight loss (17% of preoperative weight) and had repeat ultrasounds. Six of the 14 placebo-treated patients (43%) developed gallstones: two became symptomatic, requiring cholecystectomy. There was no correlation between the risk of developing gallstones and pretreatment bile composition or the degree of weight loss. None of 10 patients or ursodeoxycholic acid formed gallstones.

Conclusions: Morbid obesity is associated with gallbladder bile supersaturated with cholesterol. A high percentage will develop gallstones following gastroplasty. This can be prevented by ursodeoxycholic acid therapy.