[Inappropriate calcitriol secretion syndrome]

Abstract

The "syndrome of inappropriate calcitriol secretion" may be observed in diseases with disseminated granulomas. The main examples are sarcoidosis and tuberculosis, but it can also be observed in fungal infections, in granulomas due to foreign bodies and in lymphomas. The syndrome is due to autonomous production of 1 alpha hydroxylase by granulomas. The insuing synthesis of calcitriol escapes normal regulation by serum calcium and phosphate levels. The syndrome includes hypercalcemia, hypercalciuria, high 1,25(OH)2D3 serum levels and reduced PTH secretion. It can supervene in anephric or hypoparathyroid patients. The notion that calcitriol may be secreted extrarenally is new. It could have important bearings on several issues in nephrology, immunology and oncology.