Calcium absorption and bone mineral content in patients subjected to ileal bypass because of familial hypercholesterolaemia.

Calcium absorption and bone mineral content were studied prospectively in 30 patients with familial hypercholesterolaemia subjected to partial ileal bypass surgery. One-third of the patients were followed up for 10 years after the operation. Six months postoperatively calcium absorption decreased significantly, from a median of 16% to 13%. The effect persisted up to 5 years of follow-up study. Ten years after the operation the absorption of calcium (median, 14.5%) was not significantly different from the preoperative calcium absorption (median, 16%). Bone mineral content, measured in 76% of the patients, was retained in all patients studied. A significant correlation was present between calcium absorption and urinary calcium. The reduction in calcium absorption did not correlate with increases in faecal fat. Other long-term side effects were persistent diarrhoea and moderate steatorrhoea. A significant weight loss was slowly regained in most patients. An increase of renal oxalate excretion was only small and transient in most patients. The study shows that bypass of the terminal 200 cm of ileum for familial hypercholesterolaemia causes moderate diarrhoea and steatorrhoea in most patients but only a slight reduction of intestinal calcium absorption and apparently no risk of bone demineralization. A benefit of a postoperative calcium and vitamin D supply cannot be excluded.