What is the treatment for hypermagnesemia?

Treatment of Hypermagnesemia

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

Immediate Management Algorithm

Step 1: Discontinue Magnesium Sources

• Stop all magnesium-containing medications, supplements, laxatives, and antacids immediately 2, 3
• Identify and remove retained magnesium products in the gastrointestinal tract (particularly magnesium oxide tablets which can cause rebound hypermagnesemia) 3

Step 2: Assess Severity and Clinical Context

Severe hypermagnesemia (>6 mEq/L) with cardiovascular compromise:

• Bradycardia, hypotension, cardiac arrhythmias, or cardiac arrest 1
• Altered mental status, respiratory depression, or cardiorespiratory arrest 1

Moderate hypermagnesemia (2.2-6 mEq/L):

• Neurological symptoms: muscular weakness, paralysis, ataxia, drowsiness, confusion 1
• Vasodilation and hypotension 1

Step 3: Initiate Specific Treatment Based on Severity

For Cardiac Arrest or Severe Cardiotoxicity:

• Administer IV calcium immediately as an antagonist 1, 3
  • Calcium chloride 10%: 5-10 mL IV over 2-5 minutes 1
  • OR calcium gluconate 10%: 15-30 mL IV over 2-5 minutes 1
• Continue standard ACLS protocols 1
• Multiple doses of calcium may be required for hemodynamic improvement 3, 4

For Symptomatic Hypermagnesemia Without Cardiac Arrest:

• IV calcium gluconate for cardioprotection and symptom reversal 3, 4
• Aggressive IV fluid resuscitation 4, 5
• Loop diuretics (furosemide) as adjunct to enhance renal excretion (only in patients with adequate renal function) 4

Step 4: Consider Renal Replacement Therapy

Dialysis is the definitive treatment for severe hypermagnesemia and should be initiated when:

• Magnesium levels >9.5 mg/dL (>3.91 mmol/L) 4
• Hemodynamic instability despite calcium and fluid therapy 3, 4
• Renal impairment preventing adequate magnesium clearance 6, 3
• Continuous renal replacement therapy (CRRT) or hemodialysis results in rapid correction of magnesium levels 6, 4

Important caveat: Dialysis may not be required in patients with normal renal function if aggressive supportive care is provided early 5

Step 5: Gastrointestinal Decontamination

For ingestion of magnesium-containing products:

• Use magnesium-free laxatives to clear retained magnesium tablets from the colon 3
• Abdominal imaging (CT) may identify hyperdense magnesium tablets retained in the GI tract 3
• Incomplete GI decontamination leads to rebound hypermagnesemia despite dialysis 3

Step 6: Supportive Care

• Ventilatory support for respiratory depression or hypoventilation 1, 5
• Transcutaneous pacing for refractory bradycardia 3
• Inotropic support for persistent hypotension (though response may be minimal until magnesium levels decrease) 3
• Continuous cardiac monitoring 1

Special Populations

Patients with Renal Impairment:

• Hypermagnesemia most commonly occurs in end-stage renal disease patients taking magnesium-containing laxatives 6
• Hemodialysis is both therapeutic and preventive 6
• Regular monitoring of magnesium levels is essential 6, 2

Obstetric Patients:

• Severe hypermagnesemia most likely occurs in patients receiving IV magnesium for preeclampsia or eclampsia 1
• Lower threshold for calcium administration and close monitoring 1

Patients with Normal Renal Function:

• Hypermagnesemia can still occur with excessive intake, particularly with prolonged colonic retention 3, 5
• Recovery is possible with supportive care alone (calcium, fluids, ventilatory support) without dialysis 5

Critical Pitfalls to Avoid

• Do not underestimate rebound hypermagnesemia: Incomplete removal of magnesium from the GI tract causes persistent absorption and recurrent elevation despite initial treatment 3
• Do not delay dialysis in severe cases: Prolonged hypotension and decreased perfusion can lead to irreversible hypoxic encephalopathy 3
• Avoid magnesium-containing laxatives in patients with renal impairment or constipation with prolonged colonic transit time 1, 6
• Monitor for cardiovascular collapse during preparation for dialysis: Cardiac arrest can occur even while initiating CRRT 6