Vitamin D Metabolism in Hypoparathyroidism

Publisher Website
Google Scholar
Abstract
Only moderately reduced serum 1,25-dihydroxyvitamin D [1,25(OH)2D3] levels were found in 13 hypoparathyroid patient; factors other than parathyroid hormone can mediate the basal production of 1,25(OH)2D3. A significant correlation was found between the levels of circulating 25-hydroxyvitamin D (25OHD) and 1,25(OH)2D3. Apparently a high concentration of 25OHD was able to increase the renal production of 1,25(OH)2D, but hypocalcemia and changes in serum phosphate became less important in the present situation. The serum 25OHD and 1,25(OH)2D concentrations were followed during the change of treatment from ergocalciferol to 1.alpha.-hydroxycholecalciferol (1.alpha.-OHD3). A biological half-life of 3 wk was estimated for the plasma 25OHD. The increase in serum 1,25(OH)2D correlated with the dose of 1.alpha.-OHD3 given; no correlation was found between the serum Ca level and the 1,25(OH)2D concentration. Unexpected increases and decreases in serum Ca were observed at the same dose of 1.alpha.-OHD3 in the same patient and at serum 1,25(OH)2D concentrations within the physiological range.