Prospective study of malabsorption induced risk of gall stone formation in relation to fall in plasma cholesterol.

The relationship between cholesterol in plasma and risk of gall stone formation was investigated in 210 obese patients who underwent jejunoileal bypass surgery and were free of gall stone disease at the time. Among 185, successfully reexamined on average 19 months after surgery, 26 (14%) developed gall stones. The fall in plasma cholesterol after surgery exhibited a U-shaped relation to risk of gall stone formation with a minimum risk around the average fall (2.6 mmol/l). This was confirmed by multivariate logistic regression analysis (p less than 0.01) taking into account other possible determinants. The relation was not significantly dependent on weight loss or ratio between jejunum and ileum left in function. The study suggests that malabsorption induced fall in plasma cholesterol is related to risk of gall stone formation by two oppositely working mechanisms, one enhancing and one reducing the risk.