Marked Hypocalcemia after Tocolytic Magnesium Sulphate Therapy

ABSTRACT

Symptomatic hypocalcemia has been reported infrequently in association with magnesium sulfate (MgSO₄) tocolytic therapy. We report a 38-year-old woman who presented in preterm labor at 24 3/7 weeks. Twenty hours after starting MgSO₄, she developed chest pain. Studies revealed therapeutic serum Mg level, total serum calcium (Ca) = 5.5 mg/dL, 24-hour urine Ca = 763.9 mg, and low serum uric acid and phosphate levels. All studies corrected day 1 postpartum; urine Ca level corrected on day 2. Even short courses of MgSO₄ can result in severe hypocalcemia, raising the question of whether Ca levels should be routinely monitored.

KEYWORDS

Magnesium sulfate - tocolysis - asymptomatic hypocalcemia

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