Hypomagnesemia

Background

• Hypokalemia, Hypocalcemia and hypophosphatemia are often also present

Clinical Features

• CNS
  • Muscle weakness
  • Ataxia
  • Confusion
  • Seizures
  • Coma
• GI
  • Dysphagia
• Cardiovascular
  • CHF
  • Dysrhythmias
  • Hypotension
• Miscellaneous
  • Hypokalemia
  • Hypocalcemia
  • Anemia

Differential Diagnosis

Causes of hypomagnesemia

• ETOH
• Malnutrition
• Cirrhosis
• Pancreatitis
• After DKA
• GI loss (especially diarrhea)
• Renal wasting
  • Furosemide
  • Hypophosphatemia
• Type 2 diabetes mellitus

Evaluation

• Magnesium level
• Also check:
  • Chemistry
  • Phosphate

Management

• Serum level >1.7
  • No treatment
• Serum level 1.2 - 1.7
  • Asymptomatic
    • Oral repletion with magnesium oxide 400mg PO
      • Magnesium oxide 400mg = 2g of MgSO4
  • Symptomatic (or no POs)
    • 2g MgSO4 IV over 1 hour
• Serum level <1.2
  • 4g MgSO4 IV over 2 hours

See Also

• Electrolyte Abnormalities (Main)
• Magnesium