Calcium Balance and Bone Mineral Content Following Small-Intestinal Resection

Abstract

Net absorption of calcium, calcium balance and bone mineral content were studied in 83 patients with small-bowel resections of various lengths, mainly owing to CIBD, while they were receiving a standardized diet supplying 70 g fat and 800 mg calcium. Median duration of disease was 9 years (range, 5 months to 53 years) and median length of time from resection 3 years (range, 2 months to 18 years). In the whole case material net absorption of calcium ranged from +573 to −268 mg/day; median, +65 mg/day (+56% to −26% of dietary calcium; median, +6%). A weak inverse correlation was found between net absorption of calcium and length of resected small bowel, both in patients with ileostomy (no. = 32, r = −0.43, p < 0.01) and in patients with part of or the whole colon in function (no. = 51, r=−0.34, p < 0.01). Net absorption of calcium and urinary calcium correlated only weakly (no. = 78, r = 0.39, p < 0.001). In all patients studied the median calcium balance was −49 mg/day (range. +447 to −339 mg/day). No difference in net absorption of calcium or calcium balance could be demonstrated between patients with ileostomy and patients with colon in function. Nor did serum ionized calcium correlate with net absorption of calcium or calcium balance. Eleven per cent of 64 patients studied had significantly decreased bone mineral content, and more than half had bone mineral content below the mean value for 191 normal controls. No correlation was observed between bone mineral content and net absorption of calcium, calcium balance, duration of disease. or length of time from resection. On the basis of this cross-sectional study of the incidence and severity of negative calcium balance and skeletal demineralization, prospective, longitudinal studies should be carried out to find the most suitable form of treatment for disturbances in bone mineral metabolism after small-bowel resection owing to CIBD.