A Rare Case of Hyperkalemia Following Magnesium Sulfate Therapy in a Pregnant Patient With Preeclampsia

A 21-year-old woman at 36 weeks’ gestation presented with preeclampsia and received intravenous magnesium sulfate for seizure prevention. Her magnesium level peaked at 7.4 mg/dL on day 2. By day 4, her potassium level peaked at 6.3 mmol/L, with peaked T waves on electrocardiogram. She was treated with potassium-lowering therapy, and her kidney function remained normal, though aldosterone levels were slightly low. Given the rise in her potassium level following hypermagnesemia and its normalization after her magnesium level decreased, hyperkalemia was attributed to an elevated magnesium level. This is the fourth reported case of hyperkalemia following magnesium administration.