Reversible High-Degree Atrioventricular Block Associated With Magnesium Toxicity in Severe Pre-Eclampsia.

We report a 35-year-old woman at 31 weeks and 5 days' gestation with severe pre-eclampsia and acute kidney injury who developed symptomatic hypermagnesemia (4.49 mmol/L) and 2:1 second-degree atrioventricular block after receiving a standard Pritchard magnesium sulfate regimen. Magnesium sulfate was discontinued, intravenous calcium gluconate was administered, and emergency cesarean delivery was performed. The atrioventricular block resolved completely, and the mother recovered well. This case highlights a rare but reversible manifestation of magnesium toxicity and the importance of early recognition in patients with deteriorating renal function.