The effects of vitamin D, 2.5 mg (100,000 U)/d for 4 d, on serum calcium, serum 25-hydroxyvitamin D (25-OHD), and serum 1α,25-dihydroxyvitamin D [1α,25(OH)2D] were compared in 17 normal subjects and 6 patients with sarcoidosis who had normocalcemia and no history of hypercalcemia. The diagnosis was confirmed histologically in each of them. Vitamin D increased mean serum 25-OHD from 30±4 to 99±15 ng/ml (P < 0.001) and did not change mean serum 1α,25(OH)2D (32±3 vs. 29±3 pg/ml) or mean serum calcium (9.5±0.1 vs. 9.6±0.1 mg/dl) in the normal subjects. In contrast, vitamin D increased mean serum 25-OHD from 19±3 to 65±19 ng/ml (p < 0.05), increased mean serum 1α,25(OH)2D threefold from 40±7 to 120±24 pg/ml, and increased mean serum calcium from 9.4±0.2 to 9.8±0.2 mg/dl (P < 0.01). There was a significant positive correlation between the serum 1α,25(OH)2D and serum calcium in these individuals (r = 0.663, P < 0.01) but not in the normal subjects. The results (a) provide further evidence for abnormal regulation of circulating 1α,25(OH)2D in sarcoidosis and (b) indicate that the abnormality may exist in patients with normal calcium metabolism. Thus, the defect in vitamin D metabolism in sarcoid apparently is more common than was previousl recognized.
ASJC Scopus subject areas