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G6PD Test

What Is a G6PD Test?

A G6PD test measures levels of glucose-6-phosphate dehydrogenase (G6PD), an enzyme in your blood. An enzyme is a type of protein that’s important for cell function.

G6PD helps red blood cells function normally. It also protects them from potentially harmful by-products that can accumulate when your body is fighting infection, or as the result of certain medications.

A G6PD test is a simple test that requires a blood sample. It’s typically ordered to test for G6PD deficiencies.

Why Is a G6PD Test Used?

A G6PD deficiency is an inherited disorder (by X-linked recessive transmission). It can lead to a certain type of anemia known as hemolytic anemia. Anemia is a blood disorder in which the body doesn’t have enough red blood cells.

G6PD protects oxygen-rich red blood cells (RBCs) from chemicals called reactive oxygen species (ROS). ROS build up in your body during a fever, infection, or when you take certain medications. If your G6PD levels are too low, your RBCs won’t be protected from these chemicals. The blood cells will die, leading to anemia.

Certain foods, medications, infections, and severe stress can trigger a hemolytic episode, which is the rapid destruction of RBCs. In people with hemolytic anemia, the body can’t produce enough RBCs to replace those that have been destroyed.

Your doctor may order a G6PD test if they suspect you have hemolytic anemia based on symptoms such as:

  • an enlarged spleen
  • fainting
  • fatigue
  • jaundice
  • pale skin
  • rapid heart rate
  • red or brown urine
  • shortness of breath

A G6PD test is most often ordered after a doctor has ruled out other causes of anemia and jaundice. They’ll perform the test once a hemolytic episode has subsided.

Your doctor may also order the test to monitor treatments or confirm the findings of other blood tests.

Risks of a G6PD Test

Blood draws are routine procedures that rarely cause serious side effects. In very rare cases, the risks of giving a blood sample can include:

  • bleeding under your skin (hematoma)
  • excessive bleeding
  • fainting
  • infection at the site of needle puncture

How to Prepare for a G6PD Test

Some medications can interfere with results. Tell your doctor which medications you’re taking, including prescriptions and nutritional supplements. They may advise you to stop taking them before your G6PD test.

Let your doctor know if you’ve recently eaten fava beans or taken sulfa drugs, such as antibacterial drugs, diuretics (water pills), or anticonvulsants. This can produce adverse reactions, especially in people with G6PD deficiencies.

Your G6PD test may be delayed if you’re experiencing a hemolytic episode. Many cells with low levels of G6PD are destroyed during an episode. As a result, your test results may show falsely normal G6PD levels.

Your doctor will give you complete instructions on how to prepare for your blood draw.

How a G6PD Test Is Performed

The blood draw may be performed in a hospital or specialized testing facility.

A nurse or technician will clean the site before the test to prevent any microorganisms on your skin from contaminating it. Then they’ll wrap a cuff or other pressure device around your arm. This will help your veins become more visible.

The technician will draw several samples of blood from your arm. They’ll place gauze and a bandage over the puncture site once the test is completed.

Your blood samples will be sent to a laboratory for testing. Results will be forwarded to your doctor when they’re complete.

After a G6PD Test

Your doctor will discuss the results from your G6PD test at a follow-up appointment.

Low levels of G6PD in your blood indicate an inherited deficiency. There’s no cure for this disorder. However, you can prevent hemolytic episodes and anemic symptoms by avoiding certain triggers.

According to the American Academy of Physicians, triggers related to a G6PD deficiency include:

  • eating fava beans
  • taking aspirin and nonsteroidal anti-inflammatory drugs, such as ibuprofen
  • sulfa drugs, which are used to treat bacterial or fungal infections
  • naphthalene, a compound found in moth repellent and toilet bowl deodorizers

Your doctor will discuss your results with you and any follow-up steps you should take.

Content licensed from:

Written by: Brian Krans
Medically reviewed on: Dec 22, 2015: Steven Kim, MD

This feature is for informational purposes only and should not be used to replace the care and information received from your health care provider. Please consult a health care professional with any health concerns you may have.
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