Age-dependent bone loss after gastrectomy

Regulation of vitamin D and calcium metabolism after gastrectomy

Fifteen men, who had undergone Billroth I gastrectomy and 19 men who had undergone Billroth II gastrectomy were studied with respect to vitamin D and other indices of calcium metabolism. The Billroth I group had hypocalcaemia, raised concentration of serum alkaline phosphatase, and reduced bone mineral content. The same biochemical disturbances were found in the Billroth II group, but bone mineral content was normal. In neither of the groups was found signs of increased bone resorption. The calcium absorption was situated in the lower part of the normal range and the fractional absorption and elimination rates were normal. The 25OHD concentrations in both groups were reduced (p less than 0.05-0.01) and the 1.25(OH)2D concentrations raised (p less than 0.01-0.001). The 1,25(OH)2D concentrations were inversely related to bone mineral content, but directly related to signs of bone turnover and calcium absorption. We suggest that the high 1,25(OH)2D concentration is the result of a compensatory process with the aim of preventing hypocalcaemia.

Vitamin D status after total gastrectomy

Serum levels of 25-hydroxyvitamin D, 24,25-dihydroxyvitamin D, 1,25-dihydroxyvitamin D, immunoreactive parathyroid hormone, and urinary excretion of nephrogenous cyclic AMP were measured in 25 patients after total gastrectomy. Two types of reconstruction after total gastrectomy were also compared. Serum 25-hydroxyvitamin D levels were significantly decreased and serum 24,25-dihydroxyvitamin D levels were markedly reduced, whereas serum 1,25-dihydroxyvitamin D levels were significantly increased in the patients. Although serum levels of immunoreactive parathyroid hormone did not show a significant difference, serum alkaline phosphatase levels and urinary excretion of nephrogenous cyclic AMP were significantly increased in the patients. The results suggest that defective vitamin D storage and enhanced vitamin D action coexist in patients after total gastrectomy and that the enhanced vitamin D action, possibly derived from slightly increased parathyroid function, would be a compensatory mechanism to sustained calcium deficiency. No substantial difference of vitamin D status was observed between the two types of reconstruction which differed in passage through the duodenum.