What is the recommended treatment for magnesium deficiency?

Treatment of Magnesium Deficiency

For magnesium deficiency, oral supplementation with organic magnesium salts (aspartate, citrate, lactate) at 400-500 mg daily is recommended for mild cases, while severe deficiency requires IV magnesium sulfate at 1-2 g every six hours or up to 5 g over three hours. 1

Diagnosis and Assessment

• Hypomagnesemia is defined as serum magnesium < 1.8 mg/dL (< 0.74 mmol/L)

• Clinical manifestations typically appear when levels fall below 1.2 mg/dL and include:

  • Neuromuscular symptoms: tremors, fasciculations, tetany, seizures
  • Cardiac abnormalities: QT prolongation, arrhythmias
  • Psychiatric symptoms: confusion, irritability
  • Associated electrolyte disturbances: refractory hypokalemia and hypocalcemia 1

• Important to check other electrolytes (potassium, calcium) and ECG for comprehensive assessment

Treatment Algorithm

Mild to Moderate Deficiency (Asymptomatic, Mg levels 1.2-1.8 mg/dL)

• First-line: Oral magnesium supplementation
  • Preferred forms: Organic magnesium salts (aspartate, citrate, lactate) at 400-500 mg daily 1
  • These forms have superior bioavailability compared to magnesium oxide
  • Divide doses throughout the day to improve tolerance and absorption
  • Target serum level: >1.5 mg/dL (>0.6 mmol/L)

Severe Deficiency (Symptomatic or Mg levels <1.2 mg/dL)

• First-line: IV magnesium sulfate
  • Initial dose: 1-2 g (8-16 mEq) IV every six hours for four doses 2
  • For severe hypomagnesemia: Up to 5 g (40 mEq) added to 1L of IV fluid for slow infusion over 3 hours 2
  • Do not exceed infusion rate of 150 mg/minute except in severe cases 2
  • Continuous ECG monitoring recommended during IV administration 1

Special Considerations

• Renal impairment: Reduce dosage and monitor closely as magnesium is primarily excreted by the kidneys 1, 2
• Side effects of oral supplementation: Diarrhea (most common), abdominal cramping, nausea
  • If diarrhea occurs, reduce dose and gradually increase as tolerated 1
• Monitoring: Check serum magnesium levels regularly during treatment
• Maintenance therapy: After correction of deficiency, consider dietary changes and/or ongoing supplementation if risk factors persist

Dietary Recommendations

• Encourage magnesium-rich foods:
  • Leafy green vegetables (spinach, kale)
  • Nuts and seeds
  • Legumes
  • Whole grains
  • Fish and lean meats 1
• Recommended daily allowance: 350 mg for women, 420 mg for men 1

High-Risk Populations

Monitor magnesium levels closely in:

• Patients on medications that cause magnesium wasting (diuretics, certain antibiotics, chemotherapy agents)
• Those with gastrointestinal disorders affecting absorption
• Patients with alcoholism, diabetes, or liver disease
• Athletes in weight-control sports or with restricted eating patterns 1

Clinical Pearls and Pitfalls

• Serum magnesium levels may not accurately reflect total body magnesium status; normal levels can mask deficiency 3
• Magnesium deficiency can cause refractory hypokalemia and hypocalcemia that won't respond to replacement until magnesium is corrected 1
• Long-term oral magnesium supplementation (6 weeks) can effectively restore magnesium stores with comparable results to parenteral administration 4
• Continuous maternal administration of magnesium sulfate in pregnancy beyond 5-7 days can cause fetal abnormalities 2