Glucose-6-phosphate dehydrogenase (G-6-PD) deficiency is a relatively common X-linked incompletely dominant hereditary disorder. Since its structural gene defect is located on the X chromosome, males are more frequently affected. Among female heterozygotes, one-third may also develop the condition. The hemolytic anemia caused by this enzyme deficiency can be classified into five clinical types based on different triggering factors, namely:

1. Neonatal hyperbilirubinemia.
2. Primaquine-induced drug hemolytic anemia.
3. Favism.
4. Infection-induced anemia.
5. Congenital nonspherocytic hemolytic anemia type I.

bubble_chart Clinical Manifestations

1. Neonatal hyperbilirubinemia: Presents as newborn disease rational jaundice. Severe cases can lead to bilirubin encephalopathy. Infections, pathological delivery, hypoxia, breastfeeding mothers taking oxidizing drugs, or newborns' exposure to mothballs (naphthalene) may be contributing factors, but sometimes no cause can be identified.
2. Primaquine-induced hemolytic anemia: Acute hemolytic anemia occurs 1–3 days after taking certain oxidizing drugs (such as certain antimalarials, analgesic-antipyretics, nitrofurans, sulfonamides, ketones, naphthalene, aniline, vitamins K3 and K4, quinidine, probenecid, etc.).
3. Favism: Mostly occurs during the fava bean harvest season, with a history of consuming fava beans. Breastfeeding mothers eating fava beans can also cause the disease in infants. Symptoms usually appear within 24–48 hours after ingestion. The main manifestation is acute intravascular hemolysis. Mild cases may resolve spontaneously after 2–3 days.
4. Infection: Hemolysis can be triggered by various viral and bacterial infections, leading to sudden hemolysis within a few days, usually mild.
5. Congenital nonspherocytic hemolytic anemia type I: Chronic hemolytic anemia (extravascular hemolysis) and hepatosplenomegaly appear from childhood. Acute hemolysis (hemolytic crisis) may occur due to infection or medication.

bubble_chart Auxiliary Examination

The following laboratory tests can confirm G-6-PD deficiency.

1. Methemoglobin reduction test: Normal reduction rate >75%, 74～31% is intermediate type, <30%為顯著酶缺陷。
2. Heinz body formation test: Positive cells >5% during hemolysis, negative when hemolysis stops.
3. Fluorescent spot test: Normal red blood cells show fluorescent spots under ultraviolet light (wavelength 340nm), no fluorescence occurs with G-6-PD deficiency.
4. Blood smear elution staining method: Normal cell ghost <2%。本病女性純合子及男性雜合子>80%, female heterozygotes 20～79%.
5. G-6-PD activity assay: Activity is reduced compared to normal controls.

bubble_chart Treatment Measures

1. Remove predisposing factors: such as avoiding oxidative drugs, refraining from consuming fava beans, and actively preventing and treating infections.
2. Blood transfusion: Patients with mild anemia do not require transfusion. Those with severe anemia should receive an appropriate amount of blood transfusion, usually 1-2 times, and the donor should be a non-family member with normal G-6-PD.
3. General treatment: Depending on the severity and urgency of hemolysis, ensure adequate hydration, expand blood volume, correct shock, address electrolyte imbalances, and alkalinize urine to prevent hemoglobin deposition in renal tubules. For neonatal hyperbilirubinemia, phototherapy should be applied along with vitamin B2 supplementation. Pay attention to the prevention and treatment of hyperkalemia and renal failure.