Treatment of Hypermagnesemia
Immediately administer intravenous calcium as first-line treatment for hypermagnesemia, particularly in patients with cardiac manifestations or severe toxicity, followed by discontinuation of magnesium sources and consideration of dialysis for severe cases. 1
Immediate Management: Calcium Administration
Intravenous calcium is the cornerstone of acute hypermagnesemia treatment because it directly antagonizes magnesium's cardiotoxic and neuromuscular effects, though it does not lower serum magnesium levels. 1
Calcium Dosing Options:
- Calcium chloride 10%: 5-10 mL IV over 2-5 minutes 1, 2
- OR calcium gluconate 10%: 15-30 mL IV over 2-5 minutes 1, 2
The American Heart Association specifically recommends calcium as first-line therapy, especially for cardiac arrest or severe cardiotoxicity associated with hypermagnesemia. 1 This intervention is critical because hypermagnesemia causes bradycardia, cardiac arrhythmias, hypotension, and can progress to cardiorespiratory arrest. 1, 2
Discontinue Magnesium Sources
Stop all magnesium-containing medications, supplements, laxatives, and antacids immediately. 3 Common culprits include magnesium hydroxide for constipation, Epsom salts, and IV magnesium sulfate used in obstetric settings for preeclampsia/eclampsia. 2, 4, 5
This is particularly critical because hypermagnesemia can occur even in patients with normal renal function when excessive magnesium intake is present. 4, 6
Fluid Therapy and Diuresis
Administer generous intravenous fluids with loop diuretics (furosemide) to enhance renal magnesium excretion in patients with adequate kidney function. 5 This approach promotes magnesium elimination through increased urinary output but has limited efficacy in severe cases. 5
Dialysis for Severe Cases
Initiate dialysis (hemodialysis or continuous renal replacement therapy) for severe hypermagnesemia, particularly when:
- Magnesium levels are markedly elevated (>9-10 mg/dL or >3.7-4.1 mmol/L) 4, 5
- Patients have renal dysfunction preventing adequate magnesium clearance 4, 3
- Cardiovascular or respiratory compromise is present 5
- Conventional therapy (calcium, fluids, diuretics) shows minimal improvement 5
Dialysis results in rapid correction of magnesium levels and is the most effective method for removing excess magnesium from the body. 5, 6 For patients on kidney replacement therapy, use dialysis solutions with appropriate magnesium concentrations to prevent further electrolyte disturbances. 1
High-Risk Populations Requiring Vigilance
Monitor serum magnesium levels closely in:
- Pregnant patients receiving IV magnesium sulfate for preeclampsia/eclampsia (the most common scenario for severe hypermagnesemia) 2
- Patients with impaired renal function taking any magnesium-containing preparations 4, 3
- Elderly patients using magnesium-containing laxatives or antacids 4
- Patients with intestinal disease who may have increased magnesium absorption 6
Clinical Pitfalls to Avoid
Do not delay calcium administration while waiting for dialysis setup in symptomatic patients, as calcium provides immediate cardioprotection even though it doesn't lower magnesium levels. 1
Do not rely solely on fluid therapy and diuretics in severe cases (magnesium >9 mg/dL), as these showed minimal improvement in documented cases and dialysis was required for definitive treatment. 5
Do not overlook hypermagnesemia in patients with normal renal function who are consuming large quantities of magnesium-containing products, as fatal cases have occurred in this population. 4, 6