- Glucose-6-phosphate dehydrogenase (G6PD) is an enzyme involved in energy production.
- G6PD is found in all cells, including red blood cells (RBCs) and helps protect them from certain toxic by-products of cellular metabolism.
- G6PD deficiency is the lack of the G6PD enzyme in the blood.
- G6PD deficiency is a genetic health problem that is most often inherited by men.
- G6PD can cause hemolytic anemia. This is when the red blood cells break down faster than the body can make them.
This condition mainly affects red blood cells, which carry oxygen from the lungs to tissues throughout the body. In affected individuals, a defect in an enzyme called glucose-6-phosphate dehydrogenase causes red blood cells to break down prematurely. This destruction of red blood cells is called hemolysis/hemolytic anemia.
This type of anemia leads to paleness, yellowing of the skin and whites of the eyes (jaundice), dark urine, fatigue, shortness of breath, and a rapid heart rate. In people with glucose-6-phosphate dehydrogenase deficiency, hemolytic anemia is most often triggered by bacterial or viral infections or by certain drugs (such as some antibiotics and medications used to treat malaria). Hemolytic anemia can also occur after eating fava beans or inhaling pollen from fava plants (a reaction called favism). Glucose-6-phosphate dehydrogenase deficiency is also a significant cause of mild to severe jaundice in newborns. Many people with this disorder, however, never experience any signs or symptoms and are unaware that they have the condition.
Treatment includes staying away from certain medicines, foods, and environmental exposures.
Note: In patients with acute hemolysis (e.g., abnormally low RBC values), testing for G-6-PD may be falsely normal because older erythrocytes with a higher enzyme deficiency have been hemolyzed. Young erythrocytes and reticulocytes have normal or near-normal enzyme activity. Normal values of G-6-PD may be measured for several weeks following a hemolytic event.
When decreased, G-6-PD, Quant. values are associated with acute hemolytic anemia when deficient individuals are exposed to oxidative stress, such as with certain medications (e.g., primaquine), infection, or ingestion of fava beans.
G6PD deficiency is inherited, passed from parent to child, due to mutations or changes in the G6PD gene that cause decreased enzyme activity.
- A deficiency in G6PD causes RBCs to become more vulnerable to breaking apart (hemolysis) under certain conditions.
- G6PD deficiency is a genetic disorder.
- When individuals who have inherited this condition are exposed to a trigger such as stress, an infection, certain drugs or other substance(s), significant changes occur in the structure of the outer layer (cell membrane) of their red blood cells.
- Hemoglobin, the life-sustaining, oxygen-transporting protein within RBCs, forms deposits (precipitates) called Heinz bodies. Some individuals may experience these reactions when exposed to fava beans, a condition called “favism.”
- With these changes, RBCs can break apart more readily, causing a decrease in the number of RBCs.
- When the body cannot produce sufficient RBCs to replace those destroyed, hemolytic anemia results and the individual may develop jaundice, weakness, fatigue, and/or shortness of breath.
G6PD deficiency is a common cause of persistent jaundice in newborns. If left untreated, this can lead to significant brain damage and mental retardation.
Most people with G6PD deficiency can lead fairly normal lives, but there is no specific treatment apart from prevention. They must be cautious and avoid certain medications such as aspirin, phenazopyridine and rasburicase, antibiotics with “sulf” in the name and dapsone, anti-malarial drugs with “quine” in the name, foods such as fava beans, and chemical substances such as naphthalene (found in moth balls). Note that fava beans, often called broad beans, are commonly grown in the Mediterranean area. Acute viral and bacterial infections can also initiate episodes of hemolytic anemia as well as elevated levels of acid in the blood (i.e., acidosis). Individuals should consult with their healthcare practitioner to get a comprehensive list of these triggers. A good starting point is the list found on the G6PD Deficiency Favism Association website [L].
With hemolytic anemia, RBCs are destroyed at an accelerated rate and the person affected becomes pale and fatigued (anemic) as their capacity for providing oxygen to their body decreases. In severe cases of RBC destruction, jaundice can also be present. Most of these episodes are self-limiting, but if a large number of RBCs are destroyed and the body cannot replace them fast enough, then the affected person may require a blood transfusion. This condition can be fatal if not treated. A small percentage of those affected with G6PD deficiency may experience chronic anemia.
What are symptoms of G6PD deficiency?
G6PD can cause hemolytic anemia. This is when the red blood cells break down faster than they are made. Symptoms of hemolytic anemia include:
- Pale skin
- Yellowing of the skin, eyes, and mouth (jaundice)
- Dark-colored urine
- Trouble with physical activity
- Enlarged spleen and liver
- Increased heart rate
- Heart murmur
Many of these symptoms can be caused by other health problems. Always see your healthcare provider for a diagnosis and a treatment plan.
- Levels of G6PD are higher in the newborn than they are in the adult.
- When high levels are seen in older patients, it invariably reflects the presence of a young red blood cell population with reticulocytosis.
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