Symptomatic hypermagnesemia

Specialty: Endocrine and metabolic.

• symptomatic elevated serum magnesium
• magnesium poisoning

Why it occurs

• Advanced acute or chronic renal failure (glomerular filtration rate less than 30 ml/min that cancels the renal clearance of magnesium, especially after taking drugs that contain it)
• Excessive exogenous intake of antacids, laxatives or supplements with magnesium salts (such as magnesium hydroxide or magnesium sulfate)
• Intravenous treatment of preeclampsia or eclampsia with magnesium sulfate without close monitoring of plasma levels or deep tendon reflexes
• Primary adrenal insufficiency or hypoaldosteronism (decrease in extracellular volume that passively increases tubular reabsorption of magnesium)
• Rhabdomyolysis or massive tumor lysis (massive release of magnesium, which is the second most abundant intracellular cation, into the extracellular bloodstream)

Initial workup

Immediate determination of serum magnesium levels; plasma calcium and phosphorus; creatinine, blood urea nitrogen (BUN) and plasma electrolytes (sodium, potassium, chlorine); arterial blood gas to document concomitant respiratory or metabolic acidosis; and continuous 12-lead electrocardiographic monitoring.

Standard management

• 10% calcium gluconate — administration of 10-20 ml slowly intravenously over 5-10 minutes; Calcium acts as a direct physiological antagonist of the cardiac and neuromuscular effects of magnesium, immediately stabilizing the cell membrane
• 0.9% physiological saline solution together with Furosemide — vigorous intravenous infusion combined with loop diuretics to induce a saline diuresis that favors calciuria and magnesuria in patients with preserved renal function
• Continuous renal replacement therapy or hemodialysis (absolute indication in patients with advanced renal failure and severe symptoms of magnesium toxicity, to purify it from the plasma quickly and effectively).