Magnesium

Hypermagnesemia

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Hypermagnesemia, High Serum Magnesium

  • Definition
  1. Serum Magnesium over 2.5 meq/L
  • Symptoms
  1. Muscle Weakness
  2. Headache
  3. Excessive thirst
  • Signs
  1. Hyporeflexia
  2. Severe findings (Serum Magnesium >10 mEq/dl)
    1. Bradyarrhythmia
    2. Hypotension
    3. Respiratory depression
    4. Pulmonary edema
  • Labs
  1. See Serum Magnesium
  2. Serum Magnesium Interpretation
    1. Normal in pregnancy: 1.3 to 2.6 mg/dl
    2. Therapeutic: 5.5-7.5 mg/dl
    3. Loss of Patellar Reflex: 10-12 mg/dl
    4. Respiratory depression: 15-17 mg/dl
    5. Paralysis: 15-17 mg/dl
    6. Cardiac Arrest: 30-35 mg/dl
  • Management
  1. Stop all Magnesium Sources
  2. Supportive Care with ABC Management
  3. Dialysis
  4. Cardiotoxicity Management: Calcium
    1. Calcium Chloride (1.4 mEq/ml)
      1. Dose: 5 ml over 10 minutes
      2. May repeat second dose in 5 minutes if EKG not improved
      3. Preferred historically for shock or cardiac instability (especially if central access)
        1. However Calcium Gluconate likely has same efficacy with better peripheral IV safety
        2. See Intravenous Calcium for differences between calcium preparations
    2. Calcium Gluconate 10% (0.4 mEq/ml)
      1. Preferred agent if only peripheral IV available (Decreased venous sclerosis with infusion)
      2. Initial dose: 10 ml over 2-5 minutes (10 minutes is lower risk if time allows)
      3. Second dose after 5 minutes if EKG not improved
      4. Advantages over Calcium Chloride