A CONSIDERATION OF THE HYPERCALCIURIA IN SARCOIDOSIS, IDIOPATHIC HYPERCALCIURIA, AND THAT PRODUCED BY VITAMIN D. A NEW SUGGESTION REGARDING CALCIUM METABOLISM*

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Abstract
Some abnormalities of calcium metabolism are considered, with particular reference to the hypercalciuria of sarcoidosis. The results of several metabolic balance studies are discussed. It appears that the 3 disturbances of calcium metabolism in sarcoid-hypercalcemia, hypercalciuria, and increased intestinal absorption[long dash]are to some extent independent of each other. In 2 cases of idiopathic hypercalciuria the high urinary calcium excretion was also associated with high intestinal absorption[long dash]a state of affairs very similar to that in sarcoidosis when hypercalcemia is not present. In both conditions a negative calcium balance was produced by using a low-calcium diet. The effects of vitamin D on calcium metabolism appear to be mainly the same 3 observed in sarcoidosis. As in sarcoid, evidence is adduced that these 3 effects may be largely independent of each other. It is suggested, however, that in these and in some other conditions (e.g., hyperparathyroidism, acromegaly) , the hypercalciuria comes first and is in some way connected with a stimulus to the intestine which leads to an increase in its absorption of calcium. In fact it appears that the intestinal absorption of calcium may be continually governed by the level of urinary calcium in normal people throughout life. This may represent a new principle of body metabolism, with reference to calcium. The disturbances of calcium metabolism in sarcoidosis can logically be explained as the effect of sensitivity to vitamin D, but one difficulty is that not all patients appear to be sensitive. Fortunately, all cases of this condition, whether sensitive to vitamin D or not, appear to respond to cortisone or its analogues.