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Unsuspected morbid hypermagnesemia in elderly patients

B A Clark1, R S Brown

  • 1Charles A. Dana Research Institute, Harvard-Thorndike Laboratory, Beth Israel Hospital, Boston, MA 02215.

Insights

Severe hypermagnesemia, often unsuspected, can occur in elderly patients with bowel disorders even without severe kidney issues. This condition can lead to serious cardiovascular and neurological problems.

Area of Science:

  • Nephrology
  • Internal Medicine
  • Clinical Toxicology

Background:

  • Investigate the incidence, causes, and outcomes of severe hypermagnesemia.
  • Retrospective analysis of hospital admissions over a 5-year period (1984-1989).

Observation:

  • Identified 8 cases of severe hypermagnesemia (serum Mg ≥ 6.0 mg/dL) primarily from magnesium ingestion.
  • Most affected patients were elderly (mean age 70 years) and had underlying bowel disorders enhancing absorption.
  • Renal insufficiency was not a prerequisite; only 1 patient had pre-existing renal failure.

Findings:

  • Etiologies included magnesium-containing cathartics and antacids.
  • Clinical consequences: hypotension (7/8), bradycardia (2/8), respiratory depression (3/8), EKG abnormalities (6/8), and altered mental status (5/8).
  • Associated hypocalcemia (5.7-7.4 mg/dL) and low anion gap (range -2 to 9) were noted in several patients.

Implications:

  • Severe hypermagnesemia can occur in elderly individuals with bowel disease, even with normal or mildly impaired renal function.
  • It may be an underdiagnosed cause of cardiovascular dysfunction, hypocalcemia, and neurological/respiratory compromise.
  • Highlights the importance of considering magnesium toxicity in elderly patients presenting with unexplained symptoms, especially after ingesting magnesium-containing products.

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