From the Guidelines
G6PD deficiency should be screened for in patients with a predisposing racial or ethnic background before starting therapy with an oxidant drug, as recommended by the most recent guidelines 1.
Overview of G6PD Deficiency
G6PD deficiency is a genetic disorder that affects the enzyme glucose-6-phosphate dehydrogenase, which helps red blood cells function properly. When someone has this condition, certain medications, foods, or infections can trigger the destruction of red blood cells, causing hemolytic anemia. The most common triggers include antimalarial drugs (particularly primaquine and chloroquine), sulfonamide antibiotics, nitrofurantoin, aspirin in high doses, fava beans, and infections.
Symptoms and Management
Symptoms during a hemolytic crisis include fatigue, rapid heartbeat, shortness of breath, jaundice, dark urine, and abdominal or back pain. Management primarily involves avoiding known triggers and promptly treating any hemolytic episodes. There is no specific medication to treat the underlying enzyme deficiency. If a hemolytic crisis occurs, treatment may include oxygen therapy, intravenous fluids, and blood transfusions in severe cases.
Prevalence and Importance of Screening
G6PD deficiency is more common in males since it's an X-linked recessive disorder, and it's particularly prevalent in people of African, Mediterranean, and Southeast Asian descent. Most people with G6PD deficiency lead normal lives when they avoid triggers, but it's essential for affected individuals to inform all healthcare providers about their condition before receiving any medications. Screening for G6PD deficiency is crucial, especially before administering certain medications like methylene blue, which can precipitate hemolysis in G6PD-deficient patients 1.
Key Considerations
- G6PD deficiency can result in hemolysis after exposure to oxidant drugs, and the most common variants are GdA– and Gdmed 1.
- Patients with G6PD deficiency should be cautious when receiving medications like methylene blue, and alternative treatments should be considered in cases of methemoglobinemia 1.
- Healthcare providers should be informed about a patient's G6PD deficiency status before starting any therapy with oxidant drugs.
From the Research
Overview of G6PD Deficiency
- G6PD deficiency is the most common human enzyme defect and one of the most common genetic disorders worldwide, with an estimated 400 million people worldwide carrying a mutation in the G6PD gene that causes deficiency of the enzyme 2.
- The deficiency affects about 400 million people worldwide and can lead to acute hemolysis after exposure to known oxidative medications, infection, or ingestion of fava beans 3.
Medications to Avoid in G6PD Deficiency
- Certain medications can trigger acute haemolytic anaemia in subjects with G6PD deficiency, including primaquine, dapsone, methylthioninium chloride (methylene blue), nitrofurantoin, phenazopyridine, rasburicase, and tolonium chloride (toluidine blue) 2, 4, 3.
- It is recommended to avoid these medications in individuals with G6PD deficiency, or to perform a G6PD diagnostic test before using them 3.
Diagnosis and Testing
- Diagnosis of G6PD can be made through detection of enzymatic activity or molecular analysis to detect known mutations of the gene encoding G6PD 3.
- G6PD deficiency testing is essential before prescribing primaquine, especially in populations where G6PD deficiency is common 4, 5.
Primaquine and G6PD Deficiency
- Primaquine can cause dose-dependent haemolysis in G6PD deficiency, and its use requires careful consideration of the patient's G6PD status 4, 5, 6.
- The risk of haemolysis with primaquine is lower with low-dose regimens (0.1-0.25 mg/kg) compared to high-dose regimens (0.75 mg/kg) 6.
Clinical Implications
- G6PD deficiency should be considered in patients who experience acute hemolysis after exposure to known oxidative medications, infection, or ingestion of fava beans 3.
- Healthcare providers should be aware of the medications that can trigger haemolysis in G6PD deficiency and take necessary precautions to prevent adverse reactions 2, 4, 3.