The myth of long-term thiazide-induced magnesium deficiency.

A group of 8 patients with essential hypertension and 12 patients with recurrent renal calcium stones were treated with 50 mg hydrochlorothiazide daily for a period of 3-10 years. Serum, erythrocyte, lymphocyte, skeletal muscle, bone and urine Mg were found to be within the normal range. In the intravenous Mg load test, all patients retained a normal percentage of the loading dose of Mg. Long-term thiazide therapy does not appear to lead to Mg depletion.