Calcium metabolism in sarcoidosis. A follow-up study with respect to parathyroid hormone and vitamin D metabolites

Abstract

Calcium metabolism was evaluated in 39 patients with sarcoidosis. Hypercalcemia and/or hypercalciuria were found in 18 patients (46%) and serum 1,25-dihydroxyvitamin D was elevated in only 4 of 13 patients in whom this could be measured. By contrast, in patients with normal calcium metabolism serum 1,25-(OH)2D varied greatly, but the mean +/- SD value 156 +/- 70 pmol/l (n = 21) was also increased. This study provides further evidence for a kidney and parathyroid independent abnormal regulation of 1,25-(OH)2D in sarcoidosis. The results of follow-up (1-4 years) of untreated (n = 16) and treated (n = 15) patients support the suggestion that 1,25-(OH)2D may reflect the systemic granulomatous process (disease activity?). The mechanism for abnormal calcium metabolism remains very complex and may not result from increased serum levels of 1,25-(OH)2D alone. There was no correlation between serum 1,25-(OH)2D and either serum calcium or urinary calcium excretion. The sensitivity of target organs to 1,25-(OH)2D may be changed, whether or not resulting in abnormal calcium metabolism.