Hypermagnesemia in a constipated female

Area of Science:

• Nephrology
• Toxicology
• Gastroenterology

Background:

• Hypermagnesemia is a rare, often iatrogenic condition.
• Magnesium oxide (MgO) ingestion in constipated patients can lead to prolonged colonic retention and hypermagnesemia.
• Treatment involves magnesium cessation, GI decontamination, and serum magnesium removal, with calcium as an antagonist.

Observation:

• A 72-year-old woman with constipation ingested MgO, presenting with altered mental status and weakness.
• Laboratory tests revealed a magnesium level of 6.2 mEq/L, leading to bradycardia and hypotension.
• Abdominal CT confirmed retained MgO tablets in the colon, and rebound hypermagnesemia occurred post-incomplete dialysis.

Findings:

• Inadequate gastrointestinal decontamination of retained MgO tablets resulted in continuous absorption and rebound hypermagnesemia.
• The patient experienced minimal cardiac improvement despite inotropics and pacing, but showed transient hemodynamic improvement with calcium administration.
• Prolonged hypotension and decreased perfusion ultimately led to hypoxic encephalopathy.

Implications:

• This case underscores the critical importance of thorough gastrointestinal decontamination in managing hypermagnesemia due to MgO tablet retention.
• Effective GI decontamination is essential to prevent continuous magnesium absorption and subsequent life-threatening complications.
• Physicians should consider aggressive GI decontamination strategies in patients with suspected or confirmed retained MgO products.