In G6PD deficiency, hemolysis is typically triggered by which of the following mechanisms?

Question

Accepted Answer

D. Oxidative stress from drugs, infections, or fava beans causing depletion of reduced glutathione. ## G6PD Deficiency: Oxidative Hemolysis Mechanism

**Key Point:** G6PD deficiency causes hemolysis through oxidative stress. The enzyme glucose-6-phosphatase dehydrogenase is critical for the pentose phosphate pathway, which generates NADPH—the cofactor needed to maintain reduced glutathione (GSH), the cell's primary antioxidant defense.

### Pathophysiology of Hemolysis
1. **Normal state:** G6PD catalyzes glucose-6-phosphate → 6-phosphogluconolactone, generating NADPH
2. **NADPH function:** Reduces oxidized glutathione (GSSG) back to reduced glutathione (GSH)
3. **GSH role:** Neutralizes reactive oxygen species (ROS) and hydrogen peroxide
4. **In G6PD deficiency:** Oxidative triggers (drugs, infections, fava beans) overwhelm the limited antioxidant capacity
5. **Result:** RBC membrane lipids and proteins oxidize → hemolysis

### Common Triggers (Mnemonic: **SANDS**)
- **S**ulfonamides
- **A**spirin (high-dose)
- **N**itrofurantoin
- **D**apsone
- **S**ulfa drugs

**Also:** Infections (bacterial, viral), fava beans, and other oxidative stressors

### Key Laboratory Features
- **Heinz bodies:** Denatured hemoglobin precipitates (visible with supravital stain)
- **Bite cells:** RBCs with Heinz bodies removed by splenic macrophages
- **Hemoglobinuria:** During acute hemolytic episodes
- **Reticulocytosis:** Elevated response to hemolysis

**High-Yield:** G6PD deficiency is **episodic hemolysis** (triggered by oxidative stress), not chronic hemolysis. Between episodes, patients are asymptomatic.

**Clinical Pearl:** Most common in males of African, Mediterranean, and Asian descent. X-linked inheritance means females are usually carriers but can be symptomatic if homozygous or have skewed X-inactivation.

Answer

A. Mechanical fragmentation of RBCs in the microvasculature

Answer

B. Splenic sequestration of RBCs due to membrane protein defects

Answer

C. Complement-mediated destruction of RBCs coated with IgG antibodies

In G6PD deficiency, hemolysis is typically triggered by which of the following mechanisms?

Explanation

G6PD Deficiency: Oxidative Hemolysis Mechanism

Pathophysiology of Hemolysis

Common Triggers (Mnemonic: SANDS)

Key Laboratory Features

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