IBCC Episode 50 - Hyper and Hypomagnesemia

Magnesium homeostasis in critical care requires careful management because serum levels frequently fail to reflect total body or intracellular stores. Hypomagnesemia often presents asymptomatically but correlates with cardiac arrhythmias like torsades de pointes and atrial fibrillation, as well as neuromuscular hyperexcitability. Because magnesium deficiency often co-occurs with hypokalemia and other electrolyte imbalances, comprehensive repletion strategies are essential. Severe cases demand continuous IV infusions rather than single boluses to ensure intracellular uptake. Conversely, hypermagnesemia is primarily a concern in patients with renal insufficiency or those undergoing aggressive magnesium therapy. Management of life-threatening hypermagnesemia involves IV calcium to counteract neuromuscular and cardiac effects, alongside efforts to enhance renal excretion or initiate dialysis. Clinicians should employ balanced diuretic strategies to prevent iatrogenic electrolyte wasting, ensuring that magnesium levels are routinely monitored alongside other critical electrolytes.