Calcium, magnesium, and free fatty acids in the formation of gallstones: a nested case-control study.

In a nested case-control study, calcium status was assessed by measurements of serum total calcium, magnesium, phosphate, ionized calcium, parathyroid hormone, albumin, total CO2 (bicarbonate), and free fatty acids in relation to gallstone formation. The subjects were recruited from a cohort study (n = 4,581) on the epidemiology of gallstones in Denmark. The cohort was examined with ultrasonography twice, in 1983 and 1988; 63 subjects developed gallstones, and among those who did not, 122 were randomly selected as controls. Subjects with gallstones had significantly increased serum concentrations of total calcium, magnesium, and bicarbonate as compared with normal subjects. The difference was only observed in women. Age, body mass index, alcohol consumption, and smoking did not influence the results when included as covariables in a logistic regression analysis. Multivariate analysis showed increased concentrations of magnesium, bicarbonate, and parathyroid hormone to be significantly associated with gallstone disease in women. No significant association was observed between gallstone disease and serum variables in men.