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Every patient has the right to choose their clotting factor pharmacy provider. The IHTC supports your right of choice and will assist you in making an informed decision.
What is G6PD?
Glucose-6-phosphate dehydrogenase (G6PD) is a substance that helps the body use sugar for energy. It is an enzyme, which means it speeds up chemical changes when the body converts sugar to energy.
The G6PD enzyme is found in all the body’s cells, but is especially important in red blood cells. These are the cells that contain hemoglobin and carry oxygen throughout the body. The G6PD enzyme protects the red blood cells from harmful chemicals or toxins, which can accumulate in your body during certain illnesses or after taking some medicines.
People with G6PD deficiency do not have enough G6PD enzyme to neutralize some chemicals or toxins. Normally, there are only tiny amounts of toxins in the body, and it is usually not a problem for the G6PD enzyme to make them harmless.
So what is the problem?
If strong chemical products are not neutralized, they can damage the hemoglobin inside red blood cells. A build-up of toxins or chemicals can cause the red blood cells to break apart and be destroyed. This makes the person anemic (reduced levels of hemoglobin and red blood cells). Sometimes the anemia can happen very quickly, as if the person suddenly lost a lot of blood after an accident.
When people with G6PD deficiency take these medications, the toxic products that form in the body can damage and destroy their red blood cells.
The process of the red blood cells with hemoglobin being destroyed is called hemolysis. This may lead to severe anemia and can cause jaundice from the build-up of hemoglobin breakdown products in the blood. Sometimes infants who experience jaundice have G6PD deficiency.
People with G6PD deficiency will receive from their healthcare provider a detailed list of medicines and substances that are known to cause problems with hemolysis. Once the cause of hemolysis is removed, the hemolysis usually stops within a short period.
Cause of G6PD Deficiency
G6PD is a genetic condition that is caused by an alteration (mutation) in the G6PD gene. This mutation prevents the normal production of the enzyme. The gene is passed on in families in an X-linked recessive pattern. This means that the gene that codes for the G6PD enzyme is located on the X-chromosome; males have one X chromosome and females have two. When a male inherits a gene for G6PD that is not functioning properly, he will have G6PD deficiency. When a female inherits a gene for G6PD deficiency she is referred to as a carrier because she has a second copy of the gene that often can compensate for the altered gene. Female carriers may or may not experience symptoms of G6PD deficiency. Carriers of G6PD deficiency have a 50% chance of passing the gene on to each of their children. Each son of a carrier has a 50% chance of having G6PD deficiency and each daughter has a 50% chance of being a carrier. Men with G6PD deficiency do not pass the gene on to any of their sons; however, all (100%) of their daughters are carriers. Often a mother has no symptoms and has no way of knowing that she is a carrier of G6PD deficiency. Carrier testing in families who are known to have G6PD deficiency is available if desired.
G6PD deficiency can occur in a person from any ethnic group. In the United States it most commonly occurs in people of African American, Mediterranean (Italian, Greek), Southeast Asian, or Middle Eastern descent.
Diagnosis of G6PD Deficiency
The only way to know if a person has G6PD deficiency is with a special blood test. Remember, G6PD deficiency is not usually a chronic problem except in rare circumstances (see section below under “chronic hemolysis”). Many people go through life without any symptoms. It becomes a problem if the person is exposed to certain chemical compounds or toxins or experiences certain infections that can cause hemolysis and lead to severe anemia.
People with G6PD deficiency have an increased risk of hemolysis and severe anemia if they have certain infections such as Fifth’s disease (parvovirus), infectious hepatitis, infectious mononucleosis (mono), pneumonia, or a blood infection.
The body produces blood cells in the bone marrow. This is the red, soft, spongy part inside the bones. Usually a person with chronic hemolysis makes more than the average amount of red blood cells (hemoglobin) to make up for the ones being constantly destroyed. This increased rate of red blood cell production can be measured by a blood test called a reticulocyte (or “retic”) count. The retic count is usually elevated in a person with chronic hemolysis. This means the body is keeping up with the demands for red blood cells and hemoglobin.
In some people with G6PD deficiency, a small amount of red blood cell destruction occurs all of the time. This form of G6PD is called “chronic hemolysis”.
For persons with the form of G6PD deficiency that is associated with chronic hemolysis, their doctor may prescribe a medication called folic acid. This vitamin supplement helps the bone marrow keep up with increased production demands. The symptoms of hemolysis and the resulting anemia may include tiredness, paleness, headache, yellow tint to the whites of the eyes or skin (jaundice or icterus), fast heart beat, shortness of breath, and dark urine (tea or coke colored). Individuals with these symptoms should inform their doctor or nurse promptly.
Special Considerations: What to Avoid
You cannot prevent G6PD deficiency, but fortunately, if you can avoid exposure to certain medicines and foods, you can prevent the more serious symptoms.
Medications: What to Take, What to Avoid
Any time persons with G6PD take any medication, whether prescribed by a doctor or over-the-counter, they should tell their doctor or pharmacist that they have G6PD deficiency to be sure that it is safe to take the medication.
The common over-the-counter treatments for fever, pain, nasal congestion and cough — acetaminophen (Tylenol), ibuprofen (Advil), pseudoephedrine (Sudafed), and guaifenesin, (Robitussin) — are usually safe at normal therapeutic doses for children with G6PD deficiency. People with G6PD deficiency should avoid medicines that contain aspirin (salicylic acid).
Common Over-the-Counter Medications to AVOID
- Pepto Bismol
Common Prescription drugs to AVOID:
- Chloroquine (Aralen)
- Mefloquine (Lariam)
Sulfonamides and Sulfones:
- Furosemide (Lasix)
- Sulfacetamide (Sulamyd)
- Sulfamethoxazole (Bactrim, Septra)
- Sulfasalazine (Azulfidine)
- Sulfisoxazole (Gantrisin)
- Nitrofurantoin (Furadantin, Macrobid, Macrodantin)
Quinolones and Fluoroquinolones:
- Ciprofloxacin (Cipro)
- Levofloxacin (Levaquin)
- Moxifloxacin (Avelox, Vigamox)
- Norfloxacin (Noroxin)
Other things to AVOID:
- Fava beans (a type of bean found in the Mediterranean)
- Glyburide (Diabeta)
- Methylene Blue (a dye)
- Moth balls (or anything containing naphthalene)
- Nitrofurazone (Furacin)
- Rasburicase (Elitek)
- Tolbutamide (Orinase)
- Toluidine Blue (a dye)
For a complete listing of medications and foods to avoid see http://www.g6pd.org.