Calcium Metabolism in Sarcoidosis.

Fifteen patients with hypercalcaemia and sarcoidosis have been studied. Twelve were males of average age 34; the three females averaged 53. Cases included widely varying sarcoid manifestations , but five gave a clear history of rather excessive ingestion of low-dosage vitamin D preparations. The data confirm that in most cases there is an undue sensitivity to all the actions of vitamin D, the situation therefore mimicking vitamin D intoxication. Two patients volunteered to receive ultraviolet irradiation and became hypercalcaemic with corresponding clinical and biochemical changes. Steroids make normal the calcium abnormalities just as they do in straight vitamin D intoxication. However, in three further patients the hypercalcaemia did not respond to steroids and was shown to be due to the presence of an overacting parathyroid gland, removal of which corrected the abnormality. There are a sufficient number of other similar cases in the literature to suggest that the development of parathyroid adenomas is another even rarer complication of sarcoidosis which must be carefully distinguished from vitamin D sensitivity. It has been known for some time that certain patients with sarcoidosis also manifest a disorder of calcium metabolism. This was discovered partly because they used to be treated with large doses of calciferol and it was obvious from the rapid intoxication which sometimes ensued that they could be unduly sensitive to this vitamin. It was then discovered that some manifested hypercalcaemia apparently spontaneously. Finally some of these patients presented with urinary stones and hypercalcuria, others with renal failure, which could not be explained as the result of involvement of the kidney by the sarcoid granulomas. These latter situations gave grounds for the suspicion that hypercalcaemia had been present previously even if not found to be present still. This was made even more likely by the occurrence in some of corneal calcification, a sign possibly pathognomonic of past or present hypercalcaemia. My own interest in the problem arose from the need to distinguish such hypercalcaemic sarcoid patients from those with hypercalcaemia of other origins. The problem was early highlighted by a mis-diagnosis I made in 1950 of primary hyper-parathyroidism in a patient who really had sarcoi-dosis. This latter patient manifested no clinical signs of sarcoidosis at the time of diagnosis although she developed a typical rash some years after I had advised her to have a neck exploration which of course was unsuccessful. This problem of differential diagnosis was not much helped …