How should a patient with the G6PD Mediterranean variant be managed, including inheritance counseling, avoidance of oxidative triggers, treatment of acute hemolysis, and follow‑up care?

Management of G6PD Mediterranean Variant

Patients with the G6PD Mediterranean variant require strict lifelong avoidance of all oxidant triggers because this variant carries a very high risk of severe, potentially life-threatening hemolysis, unlike the milder African variant. 1

Inheritance Counseling

• Counsel families that G6PD deficiency is X-linked, meaning affected males inherit the mutation from carrier mothers and will pass it to all daughters (who become carriers) but no sons. 2
• All male offspring of carrier mothers have a 50% chance of being affected, while female offspring have a 50% chance of being carriers. 2
• Emphasize that the Mediterranean variant (G6PD-B⁻) causes more severe disease than the African variant (GdA⁻), with potential for life-threatening hemolysis rather than self-limited episodes. 1, 3
• Recommend cascade screening of first-degree relatives, particularly male siblings and maternal male cousins, given the high prevalence in Mediterranean, Middle Eastern, Indian, and Southeast Asian populations. 1, 3
• Advise genetic counseling for family planning, as neonatal hyperbilirubinemia requiring phototherapy or exchange transfusion is a significant risk. 4

Strict Avoidance of Oxidative Triggers

Absolutely Contraindicated Medications

• Dapsone must never be used as it is a potent oxidant causing methemoglobinemia and severe hemolysis. 1
• Methylene blue (methylthioninium chloride) is absolutely contraindicated due to risk of severe hemolytic anemia. 1
• Primaquine is contraindicated in severe G6PD deficiency; it may only be considered if G6PD activity is >30% to <70% at reduced dosing (45 mg once weekly for 8 weeks) with intensive hematological monitoring. 1
• Tafenoquine is contraindicated when G6PD activity is <70% because it triggers severe hemolysis in Mediterranean variants. 1
• Rasburicase is absolutely contraindicated in all G6PD-deficient patients. 3
• NSAIDs including diclofenac and ibuprofen, as well as aspirin, can precipitate hemolysis and should be avoided. 3

Relatively Safe Alternatives

• Artemisinin-based combination therapies (ACTs)—including artesunate, artemether-lumefantrine, and dihydroartemisinin-piperaquine—are safe for malaria treatment in G6PD-deficient patients. 1
• Chloroquine and hydroxychloroquine at standard doses are relatively safe in most G6PD-deficient patients. 1

Non-Pharmacologic Triggers

• Fava beans (broad beans) must be strictly avoided, as they cause favism—a severe acute hemolytic crisis particularly associated with Mediterranean variants. 2, 4, 5
• Educate patients that infections are a major oxidative stressor and to seek prompt medical attention for fever or systemic illness. 3, 4

Recognition and Treatment of Acute Hemolysis

Early Warning Signs

• Teach patients to recognize the classic triad: dark red/brown urine (hemoglobinuria), sudden pallor/fatigue, and jaundice, which typically appear 24-72 hours after oxidant exposure. 3
• Additional warning signs include abdominal or back pain, which may herald severe hemolysis. 1

Acute Management Algorithm

Step 1: Immediate Cessation

• Stop all potential oxidant triggers immediately upon suspicion of hemolysis. 1

Step 2: Aggressive Hydration

• Initiate aggressive intravenous hydration to maintain urine output ≥100 mL/hour in adults (or ≥3 mL/kg/hour for patients <40 kg) to prevent hemoglobin-induced acute kidney injury. 1
• Monitor continuously for acute kidney injury from hemoglobinuria, as this is the most serious complication. 1

Step 3: Vital Sign Monitoring

• Record vital signs (heart rate, blood pressure, respiratory rate, temperature) every 4-6 hours during the initial 24-48 hours to detect tachycardia or hypotension from ongoing hemolysis. 1

Step 4: Transfusion Decision

• Transfuse red blood cells when hemoglobin falls below 7 g/dL OR when the patient develops signs of severe anemia (dyspnea, chest pain, altered mental status, hemodynamic instability), regardless of absolute hemoglobin value. 1
• Do NOT transfuse asymptomatic patients with hemoglobin ≥8 g/dL; supportive care and close observation are sufficient. 1
• Consider discontinuing hemolysis-inducing drugs when hemoglobin drops below 8.5 g/dL as a practical intervention threshold. 1

Critical Diagnostic Pitfall

• Never test G6PD enzyme activity during acute hemolysis, as reticulocytes and young RBCs have higher G6PD activity, leading to falsely normal results. 6
• Repeat G6PD testing 3 months after the acute episode for accurate diagnosis if initial testing was performed during crisis. 3

Follow-Up Care

Initial Screening and Confirmation

• Perform G6PD enzyme activity testing using qualitative screening as the first-line diagnostic test in all patients of Mediterranean, African, Indian, or Southeast Asian descent presenting with hemolysis. 1, 6
• Use quantitative testing to determine the degree of deficiency in borderline cases or when considering modified dosing of conditionally-used medications. 1

Ongoing Monitoring

• Provide written lists of contraindicated medications and foods at every visit, as medication avoidance is the cornerstone of long-term management. 1, 4
• Ensure patients wear medical alert identification indicating G6PD Mediterranean deficiency to prevent inadvertent exposure during emergency care. 4, 7
• Screen all newborns in affected families for neonatal hyperbilirubinemia, as this may require phototherapy or exchange transfusion to prevent kernicterus. 4, 8
• Educate patients that they are asymptomatic between hemolytic episodes and do not require routine hematologic monitoring unless exposed to triggers. 2, 4

Pre-Procedure Screening

• Screen for G6PD deficiency before starting any oxidant drug therapy in patients with Mediterranean, African, Indian, or Southeast Asian descent. 1
• Document G6PD status prominently in the medical record to prevent future inadvertent exposures across different healthcare settings. 7