## G6PD Deficiency: Most Common Enzymatic Hemolytic Anemia **Key Point:** Glucose-6-phosphate dehydrogenase (G6PD) deficiency is the most common enzymatic defect of glycolysis causing hemolytic anemia, affecting >400 million people worldwide, with highest prevalence in Africa, Mediterranean, and South Asian populations. ### Epidemiology - **X-linked recessive** inheritance (males predominantly affected) - **Prevalence in India:** 5–15% in certain populations - More common in males; heterozygous females may show mild symptoms ### Pathophysiology G6PD catalyzes the first step of the pentose phosphate pathway, generating NADPH for antioxidant defense: $$\text{Glucose-6-phosphate} \xrightarrow{G6PD} \text{6-phosphogluconolactone} \rightarrow \text{NADPH}$$ Deficiency → ↓NADPH → ↓glutathione reduction → oxidative stress → RBC hemolysis ### Triggers for Acute Hemolytic Episodes - **Fava beans** (classic trigger; hence "favism") - Oxidative drugs: sulfonamides, aspirin, antimalarials (primaquine), nitrofurantoin - Infections (bacterial, viral) - Acidosis, hypoxia ### Diagnostic Features | Test | Finding | |------|----------| | **Heinz bodies** | Present on supravital staining (denatured hemoglobin precipitates) | | **G6PD enzyme assay** | Reduced activity | | **Blood film** | Bite cells, blister cells (RBCs with Heinz bodies removed by spleen) | | **Reticulocyte count** | Elevated during hemolytic episode | | **Indirect bilirubin** | Elevated | **High-Yield:** **Heinz bodies on supravital staining** are pathognomonic for G6PD deficiency during acute hemolysis. **Mnemonic:** **FAVA** = Favism, Antimalarials, Aspirin, Antibiotics (sulfonamides) — common triggers **Clinical Pearl:** Most G6PD-deficient individuals are asymptomatic; hemolysis occurs only with oxidative stress. Neonatal jaundice may be the first presentation.
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