Glucose-6-Phosphate Dehydrogenase (G6PD) Deficiency
An inherited enzyme deficiency that can cause red blood cells to break down
Quick Facts
- Type: Inherited blood disorder
- Affected enzyme: G6PD, which protects red blood cells
- Common triggers: Certain drugs, fava beans, infections
- Key strategy: Avoid known triggers
Overview
Glucose-6-phosphate dehydrogenase (G6PD) deficiency is a common inherited condition in which red blood cells do not have enough of an enzyme called G6PD. This enzyme helps protect red blood cells from certain kinds of stress. Without enough of it, the cells can break apart when exposed to specific triggers.
Most people with G6PD deficiency are healthy and have no symptoms unless something triggers the breakdown of red blood cells. Common triggers include certain medications, infections, and eating fava beans. The condition is more common in males and in people whose ancestry traces to parts of Africa, the Mediterranean, the Middle East, and Asia.
Symptoms
Between triggers, most people have no symptoms. When red blood cells break down (hemolysis), usually within a day or two of exposure to a trigger, symptoms can include:
- Fatigue and weakness
- Pale or yellowish skin and yellowing of the eyes (jaundice)
- Dark, tea-colored urine
- Rapid heartbeat and shortness of breath
- Dizziness
- Abdominal or back pain in more severe episodes
In newborns, G6PD deficiency can cause jaundice that may need treatment. Most episodes in older children and adults are self-limited once the trigger is removed.
Causes
G6PD deficiency is caused by an inherited change in the gene that makes the G6PD enzyme. This gene is on the X chromosome, which is why the condition affects males more often than females.
The enzyme helps shield red blood cells from oxidative damage. When a trigger increases this kind of stress, cells with too little G6PD cannot protect themselves and break down. Common triggers include:
- Certain medications, such as some antimalarials, some antibiotics, and certain other drugs
- Fava beans
- Infections
- Certain chemicals, such as naphthalene found in some mothballs
The exact set of triggers varies from person to person and depends on how much enzyme activity is reduced. Some people react only to strong triggers, while others are more sensitive. This is why doctors often give each person a personalized list of medications and foods to avoid rather than a single universal rule.
Risk Factors
- Being male, due to the X-linked inheritance pattern
- A family history of G6PD deficiency
- Ancestry from Africa, the Mediterranean, the Middle East, or Asia
- Exposure to known triggers such as certain drugs or fava beans
Diagnosis
Diagnosis is made with blood tests, often prompted by an episode of red cell breakdown or newborn jaundice.
- G6PD enzyme test: a blood test that measures the level of G6PD activity to confirm the diagnosis
- Blood count and hemolysis tests: to detect anemia and signs that red cells are breaking down
- Newborn screening: performed in some places to identify affected babies early
Testing is best done when the person is not in the middle of a severe episode, as results can be misleading at that time.
Treatment
The cornerstone of management is avoiding triggers. Episodes are usually treated by removing the cause and supporting the body while red cell levels recover.
- Avoiding triggers: steering clear of medications, foods, and chemicals known to provoke breakdown
- Treating infections: managing illnesses that can set off an episode
- Supportive care: rest and fluids during an episode
- Blood transfusion: reserved for severe episodes with significant anemia
- Newborn jaundice care: light therapy or other treatment if jaundice is significant
Carrying a list of medications and foods to avoid, and telling health professionals about the condition, helps prevent future episodes.
Prevention
- Know and avoid your personal triggers, including specific medications
- Avoid fava beans and products that contain them
- Tell every doctor, dentist, and pharmacist that you have G6PD deficiency before starting new medicines
- Avoid mothballs and other products containing naphthalene
- Seek prompt treatment for infections
When to See a Doctor
See a doctor if you develop signs of red cell breakdown, such as unusual tiredness, pale or yellow skin, or dark urine, particularly after a new medication, illness, or eating fava beans. Seek urgent care for:
- Severe fatigue, shortness of breath, or a racing heart
- Deep yellowing of the skin or eyes
- Very dark urine with weakness
- Jaundice in a newborn, which needs prompt evaluation
Always mention your G6PD deficiency to health professionals before taking new medicines.
Frequently Asked Questions
What triggers an episode in G6PD deficiency?
Common triggers include certain medications (such as some antimalarials and antibiotics), eating fava beans, infections, and some chemicals like naphthalene in mothballs. Avoiding your known triggers is the main way to prevent episodes.
Is G6PD deficiency dangerous?
Most people are healthy and only have problems when exposed to a trigger. Episodes of red cell breakdown are usually self-limited once the trigger is removed, but severe episodes can cause significant anemia and need medical care, so knowing your triggers is important.
Why does it affect more men than women?
The G6PD gene is on the X chromosome. Because males have only one X chromosome, a single altered gene affects them, while females usually have a second normal copy that offers some protection.
Can I prevent problems if I have G6PD deficiency?
Yes, largely by avoiding triggers. Know which medications and foods to avoid, tell every doctor and pharmacist about your condition before starting new medicines, avoid fava beans and naphthalene, and treat infections promptly.
How is G6PD deficiency diagnosed?
A blood test measuring G6PD enzyme activity confirms the diagnosis, often alongside tests for anemia and red cell breakdown. It is best tested when you are not in the middle of a severe episode, as results can be misleading then.
References
- MedlinePlus, U.S. National Library of Medicine. Glucose-6-phosphate dehydrogenase deficiency.
- National Heart, Lung, and Blood Institute (NHLBI). Hemolytic Anemia.
- World Health Organization (WHO).
- Genetic and Rare Diseases Information Center (GARD).