Home Subcutaneous Magnesium Infusion in Refractory Hypomagnesemia: A Case Report

We describe a patient with renal magnesium wasting and prolonged, symptomatic hypomagnesemia that was refractory to oral therapies and intermittent intravenous infusion who achieved near-normal serum magnesium levels with subcutaneous magnesium infusions. A woman in her 40s was seen in nephrology clinic for evaluation and management of severe, chronic hypomagnesemia because of renal magnesium wasting in combination with frequent diarrhea. Clinical manifestations associated with hypomagnesemia included muscle weakness, cognitive impairment, and frequent seizures. Her hypomagnesemia had persisted for more than 20 years despite maximal oral magnesium supplementation and frequent intravenous magnesium infusions. To provide slower delivery of parenteral magnesium, she was prescribed 2 g/d of magnesium sulfate, delivered subcutaneously. This was well tolerated, rapidly normalized her serum magnesium levels, and improved her symptoms. We briefly discuss modalities used for treatment of hypomagnesemia, including shortcomings of intravenous therapy and limited literature discussing efficacy and tolerability of subcutaneous infusions. This case report demonstrates the efficacy and safety of subcutaneous magnesium infusions in a patient with refractory hypomagnesemia and suggests that subcutaneous infusion may be safe and effective for treatment of refractory hypomagnesemia in other patients with urinary magnesium wasting.