[Changes in biliary lithogenicity caused by 4 weeks' weight reduction].

In 2 of 12 patients (16.6%) cholesterol monohydrate crystals occurred in duodenal bile samples after a 4 weeks fasting period (452 kcal/day). Cholesterol monohydrate crystals could be observed until recently mainly in patients with cholesterol gallstones. Therefore, this finding indicates increased biliary lithogenicity despite a non statistical decrease in CSI from 1.35 +/- 0.35 to 1.19 +/- 0.64. Presumably the increased lithogenicity may be caused by an increased glycoprotein concentration and an improvement in gallbladder contractility. Short time fasting obviously will be a risk factor for the development of gallstones, if weight and metabolic normalisation cannot be achieved.