How to manage a patient with Glucose-6-phosphate dehydrogenase (G6PD) deficiency?

Management of Patients with G6PD Deficiency

Patients with Glucose-6-phosphate dehydrogenase (G6PD) deficiency require careful medication selection, monitoring for hemolysis, and avoidance of specific triggers to prevent potentially life-threatening hemolytic crises. 1

Diagnosis and Testing

• G6PD testing should be performed before administering medications with hemolytic potential, particularly:

  • Before prescribing primaquine for malaria
  • In patients with unexplained hemolysis
  • Individuals from high-prevalence regions (Africa, Southern Europe, Mediterranean region, Middle East, South-East Asia, and Oceania) 1, 2

• Testing options include:

  • Quantitative enzyme activity testing (gold standard)
  • Point-of-care rapid diagnostic tests (sensitivity ~100% for severe/moderate deficiency)
  • Fluorescent spot test (FST) with interpretation:
    • Absent fluorescence: Severe deficiency
    • Intermediate fluorescence: Partial deficiency
    • Bright fluorescence: Normal activity 1

Medication Management

Medications to Avoid

Based on strong evidence, the following medications should be strictly avoided in G6PD-deficient patients:

• Primaquine - Contraindicated in severe G6PD deficiency; can cause severe hemolysis 2, 3
• Dapsone - High risk of hemolysis 1, 3
• Nitrofurantoin - Can trigger hemolytic crisis 1, 3
• Phenazopyridine - Associated with hemolysis 3, 4
• Rasburicase - Contraindicated in G6PD deficiency 3
• Methylene blue - Can worsen hemolysis in G6PD deficiency 1, 3, 5
• Tolonium chloride (toluidine blue) - Should be avoided 3

Medications Requiring Caution

• Sulfonamides (including sulfamethoxazole/cotrimoxazole) - Traditional concern, but recent evidence suggests lower risk than previously thought 1, 4
• Ciprofloxacin - Requires monitoring but can be used with caution 1, 4

Safe Medication Alternatives

• Penicillins - Generally safe in G6PD deficiency 1
• Cephalosporins - Safe alternatives for infections 1
• Macrolides - Safe options for bacterial infections 1
• Most tetracyclines - Safe in adults and children >8 years 1
• Artesunate - Preferred over quinine for P. falciparum malaria 1
• Ascorbic acid (0.5-1.0 g/day in divided doses) - Can be used to treat methemoglobinemia instead of methylene blue 1, 5

Management of Malaria in G6PD Deficiency

• P. falciparum malaria: Use artesunate (2.4 mg/kg IV at 0,12, and 24 hours, then daily) instead of quinine 1
• P. vivax malaria: Avoid primaquine in severe G6PD deficiency 6, 2, 7
  • For mild to moderate G6PD deficiency, if primaquine is considered essential:
    • Assess risks and benefits carefully
    • Check baseline hematocrit and hemoglobin
    • Monitor hematological parameters closely (e.g., day 3 and 8)
    • Limit primaquine to no more than 5 days in populations with severe G6PD deficiency 6, 2
  • Discontinue primaquine immediately if signs of hemolysis occur (darkening of urine, marked fall in hemoglobin) 2

Monitoring for Hemolysis

• Monitor for signs of hemolysis during high-risk situations:

  • Darkening of urine
  • Pallor
  • Fatigue
  • Marked fall in hemoglobin or erythrocyte count 1, 2

• If hemolysis occurs:

  • Discontinue the offending agent immediately
  • Provide supportive care, including IV hydration
  • Consider blood transfusion for severe anemia 1
  • Perform serial hemoglobin measurements to track hemolysis 1

Special Considerations

Dietary and Lifestyle Recommendations

• Avoid fava beans - common dietary trigger for hemolysis 1
• Maintain adequate hydration, especially during illness 1

Special Populations

• Pregnant women: Primaquine is contraindicated due to risk to the fetus 2
• Breastfeeding women: Avoid primaquine or discontinue nursing 1
• Newborns from high-risk populations: Should be screened for G6PD deficiency 1
• Heterozygous females: May have intermediate deficiency that can still cause clinical symptoms under severe oxidative stress 1

Documentation and Patient Education

• Document G6PD status prominently in medical records
• Educate patients about:
  • Medications to avoid
  • Dietary triggers (especially fava beans)
  • Signs and symptoms of hemolysis requiring immediate medical attention
  • Importance of informing all healthcare providers about G6PD status 1