To the Editor.—
In the July 15 issue of The Journal (229:267, 1974), Palmer described a patient with hypercalcemia, presumedly secondary to chlorthalidone (Hygroton) administration. Previous reports have shown that thiazides and chlorthalidone can cause permanent hypercalcemia in patients with hyperparathyroidism.1,2 Adams et al3 suggested a provocative test with thiazides for the diagnosis of hyperparathyroidism in patients suffering from nephrolithiasis and hypercalciuria.Since the pharmacological action of chlorthalidone is similar to that of thiazides, we wonder whether the patient described by Palmer has normocalcemic hyperparathyroidism. If that be the case, the observed hypercalcemia may represent a reaction to chlorthalidone in a hyperparathyroid patient.
Weinberger A, Pinkhas J, de Vries A. Chlorthalidone-Induced Hypercalcemia. JAMA. 1975;231(2):134. doi:10.1001/jama.1975.03240140008004