Parathyroid Function in Sarcoidosis

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Abstract
Parathyroid hormone (PTH) concentration was determined by radioimmunoassay in serum specimens in 26 unselected cases of sarcoidosis. Although only six of these patients had hypercalcemia, PTH was unmeasurably low in 19. Of the seven with normal levels, five received steroid therapy at the time of study. PTH levels were low regardless of the apparent activity of the disease and were not correlated with serum calcium concentrations. PTH was unmeasurably low in sarcoidosis even when complicated by moderate renal insufficiency, a condition that ordinarily provokes secondary hyperparathyroidism. Hypercalcemic sarcoid patients with high PTH concentrations were found to have coexistent parathyroid adenomas or hyperplasia. In such cases, hypercalcemia did not respond to steroid therapy, but was corrected by surgery. The data indicate that most patients with sarcoidosis have functional hypoparathyroidism. This fits well with the recognized abnormalities of calcium metabolism in sarcoidosis, since excessive absorption of calcium from the gastrointestinal tract should reduce PTH secretion.