Magnesium: the forgotten electrolyte

Bol Asoc Med P R. 2013;105(3):17-20.


Magnesium (Mg++), Potassium (K+) and Calcium (CA++) are important electrolytes in keeping a stable electrical status. The purpose of this study was to measure them in critically ill patients.

Methods: We evaluated the electrolytes in 28 consecutive patients. Eighteen were females and 10 males with mean age of 62 +/- 5 years.

Results: The admission diagnosis in 95% of the cases was congestive heart failure. Sixty-four percent of the patients had subnormal values of Mg++, 53% subnormal values of K+, and 28% subnormal values of CA++. Fourteen percent showed lower values of the three electrolytes and 35% only of Mg++ and K+ concomitantly. Twenty-eight percent showed prolonged QTC interval. All patients with prolonged QTC interval had low Mg++ and K+ levels. Twenty five percent of the patients showed atrial fibrillation, 25% ventricular tachycardia, and 3% junctional tachycardia. The ventricular tachycardia group had more electrolyte abnormalities than those with atrial fibrillation. None of the patients received Mg++ replacement during critical management while 50% received K+ replacement.

Conclusion: This data shows physician overlook the Importance of Mg++ and K+ deficiency in critically ill patients.

MeSH terms

  • Acid-Base Imbalance / blood*
  • Acid-Base Imbalance / etiology
  • Aged
  • Critical Care / methods
  • Critical Illness*
  • Diabetes Complications / blood
  • Diagnostic Tests, Routine
  • Electrocardiography
  • Female
  • Heart Diseases / blood*
  • Heart Diseases / physiopathology
  • Humans
  • Hypertension / blood
  • Hypokalemia / blood
  • Hypokalemia / etiology
  • Intensive Care Units
  • Magnesium / blood
  • Magnesium / physiology*
  • Male
  • Middle Aged
  • Renal Insufficiency, Chronic / blood


  • Magnesium