How to treat hypermagnesemia?

Treatment of Hypermagnesemia

For cardiac arrest or severe cardiotoxicity from hypermagnesemia, administer intravenous calcium immediately (calcium chloride 10% 5-10 mL or calcium gluconate 10% 15-30 mL IV over 2-5 minutes) in addition to standard ACLS care. 1

Immediate Management Algorithm

Step 1: Discontinue All Magnesium Sources

• Stop all magnesium-containing medications, supplements, laxatives, and antacids immediately 2, 3, 4
• This is the single most critical intervention for non-emergent hypermagnesemia 4
• Check for magnesium hydroxide, magnesium oxide, magnesium sulfate, and magnesium-containing cathartics 2, 3, 5

Step 2: Assess Severity and Hemodynamic Status

Severe hypermagnesemia (>6.5 mg/dL or >2.7 mEq/L) presents with: 1

• Muscular weakness, paralysis, ataxia 1
• Drowsiness, confusion, altered mental status 1, 2
• Bradycardia, hypotension, cardiac arrhythmias 1, 3
• Hypoventilation, respiratory depression 1
• Risk of cardiorespiratory arrest 1

Step 3: Administer Calcium as Antagonist

For cardiac arrest or severe cardiotoxicity (bradycardia, arrhythmias, hypotension): 1

• Give calcium chloride 10% 5-10 mL IV over 2-5 minutes, OR 1
• Give calcium gluconate 10% 15-30 mL IV over 2-5 minutes 1
• Calcium acts as a direct antagonist to magnesium's cardiac and neuromuscular effects 3
• May need to repeat dosing for sustained hemodynamic improvement 3

Step 4: Enhance Magnesium Elimination

For patients with normal renal function: 4, 6

• Administer intravenous normal saline to promote renal excretion 4, 6
• Ensure adequate hydration and urine output 4, 6
• Most patients with normal kidney function will clear magnesium without dialysis 6

For patients with renal impairment or severe hypermagnesemia: 2, 3, 4, 5

• Hemodialysis is the definitive treatment 2, 3, 4, 5
• Continuous renal replacement therapy (CRRT) is effective for critically ill patients 2, 4
• Dialysis should be initiated urgently when magnesium levels exceed 9-10 mg/dL or with severe symptoms 2, 3, 5

Step 5: Gastrointestinal Decontamination (If Oral Ingestion)

Critical for preventing rebound hypermagnesemia: 3

• Use magnesium-free laxatives to clear retained magnesium tablets from the GI tract 3
• Imaging (CT abdomen) may show hyperdense magnesium tablets retained in the colon 3
• Incomplete GI decontamination leads to continuous absorption and rebound hypermagnesemia even after dialysis 3

Supportive Care

Respiratory support: 1, 6

• Provide mechanical ventilation if hypoventilation or respiratory failure develops 6, 5
• Monitor for progressive respiratory depression 1

Cardiovascular support: 3, 5

• High-dose inotropics may be needed for refractory hypotension 3
• Transcutaneous pacing for severe bradycardia unresponsive to calcium 3
• Monitor for myocardial infarction as a complication 5

Critical Pitfalls to Avoid

Incomplete dialysis leads to rebound hypermagnesemia if magnesium-containing substances remain in the GI tract 3

Delayed recognition is common because hypermagnesemia is unfamiliar and often overlooked 2, 4

Hypermagnesemia can occur even with normal renal function when excessive magnesium is ingested, particularly with prolonged colonic retention 2, 3, 6

Prolonged hypotension and decreased perfusion can lead to irreversible hypoxic encephalopathy despite successful magnesium reduction 3

Regular monitoring of magnesium levels is essential in patients receiving magnesium-containing preparations, especially those with any degree of renal impairment 2, 4