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
- 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
- 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
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
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
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.