A 30-year-old man plans a trip to India and is advised to take prophylaxis for malaria. Three days after beginning treatment, he develops dark urine, pallor, fatigue, and jaundice. Hematocrit is 30% (it had been 43%) and reticulocyte count is 7%. He stops taking the medication. Treatment should consist of
|B||Administration of methylene blue|
|C||Administration of vitamin E|
|E||No additional treatment is required|
No additional treatment is required
1. This patient has developed a hemolytic anemia secondary to an antimalarial drug.
2. Toxins or drugs such as primaquine, sulfamethoxazole, and nitrofurantoin cause hemolysis in patients with G6PD deficiency.
3. Since the G6PD gene is carried on the X chromosome, most affected patients are males.
4. The drugs that cause hemolysis in G6PD deficiency are oxidizing agents.
5. Oxidant stress on red blood cells is counteracted by reduced glutathione.
6. NADPH (which is required to regenerate reduced glutathione after it has been oxidized) is produced by the hexose monophosphate shunt.
7. G6PD is the first enzyme in this metabolic pathway.
8. If this enzyme is less active, the cell cannot replace GSH and succumbs to oxidizing stress. Clinically this can range from mild to life-threatening hemolysis.
In mild cases, no treatment is necessary; once the offending drug is eliminated, the hemolysis resolves.