Treatment of Hypermagnesemia
For patients with hypermagnesemia, administration of intravenous calcium (calcium chloride [10%] 5-10 mL or calcium gluconate [10%] 15-30 mL IV over 2-5 minutes) is the first-line treatment, especially in cardiac arrest or severe cardiotoxicity. 1
Clinical Presentation of Hypermagnesemia
Hypermagnesemia is defined as serum magnesium concentration >2.2 mEq/L (normal range: 1.3-2.2 mEq/L). Clinical manifestations progress with increasing severity:
- Early symptoms: muscular weakness, paralysis, ataxia, drowsiness, and confusion 1
- Moderate elevation: vasodilation and hypotension 1
- Severe elevation: depressed consciousness, bradycardia, cardiac arrhythmias, hypoventilation, and cardiorespiratory arrest 1
Risk Factors
Hypermagnesemia most commonly occurs in:
- Patients with renal impairment receiving magnesium-containing medications 2
- Obstetric patients being treated with IV magnesium for preeclampsia or eclampsia 1
- Patients taking magnesium-containing laxatives, antacids, or supplements 3, 4
- Individuals with intestinal disease that may increase magnesium absorption 5
Treatment Algorithm
1. Mild to Moderate Hypermagnesemia (2.2-5 mEq/L)
- Discontinue all magnesium-containing medications and supplements 2
- Ensure adequate hydration with intravenous fluids 6
- Monitor cardiac function and neuromuscular status 2
2. Severe Hypermagnesemia (>5 mEq/L) or Symptomatic
- Administer IV calcium to antagonize magnesium's effects:
- Calcium chloride (10%) 5-10 mL IV or
- Calcium gluconate (10%) 15-30 mL IV over 2-5 minutes 1
- Provide aggressive IV fluid therapy with normal saline 6
- Consider loop diuretics (e.g., furosemide) to enhance renal magnesium excretion in patients with adequate renal function 6
- Monitor for potential side effects of diuretics including dehydration, electrolyte imbalances, and hypotension 7
3. Life-Threatening Hypermagnesemia or Renal Failure
- Immediate hemodialysis or continuous renal replacement therapy (CRRT) for rapid correction of magnesium levels 3, 4, 6
- Continue IV calcium administration to stabilize cardiac function until dialysis can be initiated 1
- Provide supportive care for respiratory depression, including mechanical ventilation if necessary 6
Special Considerations
- For patients on kidney replacement therapy (KRT), use dialysis solutions containing appropriate magnesium concentrations to prevent further electrolyte disorders 1
- In patients with normal renal function, hypermagnesemia can still occur with excessive magnesium intake, particularly with intestinal disease 5
- Cardiac monitoring is essential during treatment as both hypermagnesemia and rapid correction can cause arrhythmias 3
Prevention
- Avoid magnesium-containing medications in patients with renal impairment 2
- Regularly monitor magnesium levels in high-risk patients 3
- Use magnesium-containing products with caution, particularly in elderly patients or those with reduced kidney function 4
Pitfalls and Caveats
- Hypermagnesemia may be overlooked due to unfamiliarity with the condition 3
- Symptoms may mimic other neurological or cardiac disorders, leading to delayed diagnosis 2
- Calcium administration antagonizes magnesium's effects but does not reduce serum magnesium levels 1
- Hemodialysis is the most effective method for rapidly reducing serum magnesium in severe cases 6