Glucose-6-phosphate dehydrogenase (G-6-PD) deficiency is a hereditary condition in which red blood cells break down when the body is exposed to certain drugs or the stress of infection.

G6PD deficiency occurs when a person is missing or doesn't have enough of an enzyme called glucose-6-phosphate dehydrogenase, which helps red blood cells work properly.

Too little G6PD leads to the destruction of red blood cells. This process is called hemolysis. When this process is actively occurring, it is called a hemolytic episode. The episodes are usually brief, because the body continues to produce new red blood cells, which have normal activity.

Red blood cell destruction can be triggered by infections, severe stress, certain foods (such as fava beans), and certain drugs, including:

• Antimalarial drugs
• Aspirin
• Nitrofurantoin
• Nonsteroidal anti-inflammatory drugs (NSAIDs)
• Quinidine
• Quinine
• Sulfonamides

Other chemicals, such as those in mothballs, can also trigger an episode.

In the United States, G6PD deficiency is more common among blacks than whites. Men are more likely to have this disorder than women.

You are more likely to develop this condition if you:

• Are African American
• Are of Middle Eastern decent, particularly Kurdish or Sephardic Jewish
• Are Male
• Have a family history of the deficiency

A form of this disorder is common in whites of Mediterranean descent. This form is also associated with acute episodes of hemolysis. Episodes are longer and more severe than in the other types of the disorder.

Persons with this condition do not display any signs of the disease until their red blood cells are exposed to certain chemicals in food or medicine, or to stress.

Symptoms are more common in men and may include:

• Dark urine
• Enlarged spleen
• Fatigue
• Paleness
• Rapid heart rate
• Shortness of breath
• Yellow skin color (jaundice)

A blood test can be done to check the level of G6PD. See: G6PD screen

Other tests that may be done include:

• Bilirubin level
• Complete blood count, including red blood cell count
• Hemoglobin - blood
• Hemoglobin - urine
• Haptoglobin level
• LDH test
• Methemoglobin reduction test
• Reticulocyte count

Treatment may involve:

• Medicines to treat an infection, if present
• Stopping any drugs that are causing red blood cell destruction
• Transfusions, in some cases

Spontaneous recovery from hemolytic crises is the usual outcome.

Rarely, kidney failure or death may occur following a severe hemolytic event.

Call for an appointment with your health care provider if you have symptoms of this condition.

Call your health care provider if you have been diagnosed with G6PD deficiency and symptoms do not disappear after treatment.

Persons with G6PD deficiency must strictly avoid things that can trigger an episode. Talk to your health care provider about your medications.

Genetic counseling or testing may be available to those who have a family history of the condition.

Hoffman R, Benz Jr. EJ, Shattil SJ, et al., eds. Hematology: Basic Principles and Practice. 4th ed. Philadelphia, Pa: Churchill Livingston; 2005:658-60.

Goldman L, Ausiello D. Cecil Textbook of Medicine. 22nd ed. Philadelphia, Pa: WB Saunders; 2004:1027-28.