SHM Converge Scientific Abstract ePoster Gallery-When Magnesium Turns Toxic: A Compelling Case of Hypermagnesemia in an Elderly Patient

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This case report describes severe hypermagnesemia in an 84-year-old woman with chronic kidney disease, chronic constipation, and cardiac comorbidities. She presented with one week of slurred speech, confusion, and somnolence after regularly taking magnesium oxide and intermittently using milk of magnesia, with a recent larger-than-usual dose before admission. Initial evaluation showed acute kidney injury, but magnesium levels were not checked until the next day, when they were elevated at 5.7 mg/dL. Her EKG demonstrated prolonged PR and QTc intervals, consistent with magnesium toxicity.<br /><br />She was treated with IV fluids, IV calcium gluconate, loop diuretics, and metolazone. Dialysis was considered but initially deferred because of bleeding risk and because her mental status improved after calcium administration. An aggressive bowel regimen was started to remove residual magnesium and reduce further absorption; she finally had a bowel movement on hospital day 4. However, her magnesium remained elevated and kidney function did not recover, suggesting progression to ESRD. She was ultimately started on hemodialysis, which normalized her magnesium levels.<br /><br />The discussion emphasizes that hypermagnesemia is rare but potentially fatal, especially in patients with renal dysfunction and in elderly patients using magnesium-containing laxatives or supplements. Constipation and slowed bowel transit can increase magnesium absorption, while hypermagnesemia itself may worsen ileus. Symptoms are often nonspecific and may include lethargy, hyporeflexia, conduction abnormalities, respiratory failure, and cardiac arrest in severe cases.<br /><br />Key management principles include stopping magnesium sources, using bowel regimens, giving IV calcium for cardioprotection, considering diuretics when renal function is adequate, and using dialysis for severe or persistent cases with renal failure. The report highlights the need for a high index of suspicion and routine consideration of serum magnesium in at-risk patients.

Asset Subtitle

Amanda Kung

Meta Tag

Author List Amanda Kung, Kazi N. Khan, Michael Choi, Sarah Thornton

Category Clinical Vignettes

Concept Magnesium Homeostasis

Concept Hypermagnesemia

Concept Renal Dysfunction

Concept Renal Disease

Concept Magnesium-Containing Laxatives

Distinguished Non-Finalist

Presenter Organization MedStar Georgetown University Hospital

Presenting Author Amanda Kung

Track Adult

Keywords

hypermagnesemia

magnesium toxicity

chronic kidney disease

magnesium oxide

milk of magnesia

elderly patient

constipation

acute kidney injury

hemodialysis

electrocardiogram abnormalities

Magnesium Homeostasis

Hypermagnesemia

Renal Dysfunction

Renal Disease

Magnesium-Containing Laxatives