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July 10, 1972

Hypocalcemia Following Magnesium Sulfate Therapy

Author Affiliations

Athens, Greece

JAMA. 1972;221(2):195. doi:10.1001/jama.1972.03200150059032

To the Editor.—  Monif and Savory (219:1469, 1972) reported the case of maternal hypocalcemia secondary to magnesium sulfate therapy for eclampsia, as an example for the interrelationship of magnesium and calcium ions in man. Such an interrelationship is known to exist, though the exact role of parathormone in magnesium homeostasis remains to be defined.1 Knowledge of the mechanism involved would have considerable implications regarding possible benefits and hazards of therapeutic use of magnesium.We had the opportunity to study the changes of magnesium, calcium, and phosphate in serum and urine after a two-hour intravenous infusion of 41.1 mEq of magnesium (as magnesium sulfate in 200 ml normal saline solution) in 22 normal volunteers, 9 male and 13 female, whose ages ranged from 17 to 61 years. Blood and urine specimens were obtained before infusion, at the end of infusion, and at one-hour intervals, for a total time of four