G6PD Test

Overview

What is a G6PD test?

A G6PD test is a blood test to measure G6PD levels. G6PD is short for glucose-6-phosphate dehydrogenase. G6PD is an enzyme (protein) that helps your red blood cells work correctly.

Your healthcare provider may order a G6PD test if they think you might not have enough G6PD (G6PD deficiency). G6PD deficiency is a genetic disorder that leads to low red blood cell levels (anemia).

What does G6PD do?

G6PD helps protect red blood cells from specific chemicals called reactive oxygen species (ROS) a type of chemical called a free radical. If you have G6PD deficiency, the lack of G6PD leaves your red blood cells vulnerable.

Without the protection of G6PD, when exposed to ROS your red blood cells respond by wearing out and popping or dying faster than your body replaces them. This causes a type of anemia called hemolytic anemia.

When would a G6PD test be needed?

You may have a G6PD test if you have symptoms of hemolytic anemia (hemolytic symptoms). Usually, you don’t develop hemolytic symptoms unless you interact with a trigger. Triggers of hemolytic symptoms include:

Symptoms that may point to hemolytic anemia include:

Why might a baby need a G6PD test?

Babies who have jaundice that doesn’t go away may need a G6PD test. Jaundice is common in newborns, but if it lasts longer than two weeks and has no obvious cause, your provider may recommend a G6PD test. Your baby may also get the G6PD test if you have a family history of G6PD deficiency.

How common is G6PD deficiency?

G6PD deficiency is relatively common. Experts believe around 400 million people worldwide have G6PD deficiency. Although G6PD deficiency is common, most people don’t have symptoms.

Symptomatic G6PD deficiency is more common in men than women. You’re also more likely to have the deficiency if you have Asian, African or Mediterranean heritage.

Test Details

How does a G6PD test work?

Healthcare providers test your G6PD levels by taking a small blood sample. During the blood test, your healthcare provider:

  1. Inserts a needle into one of your arm veins.
  2. Collects a small sample of blood.
  3. Removes the needle and places a bandage with a cotton pad over the area.

G6PD blood tests are typically quick and relatively painless. They often take less than five minutes.

If you have a fear of needles (trypanophobia), tell the nurse who is drawing your blood. You may want to practice breathing exercises, look away from the needle or bring a friend for support.

What happens during a G6PD test for a baby?

In babies, healthcare providers take blood samples by gently pricking the baby’s heel. The provider collects a small amount of blood and places a bandage over the area.

Your baby may feel a small prick when the needle goes in. Their heel may also bruise slightly. The discomfort and bruising usually goes away quickly.

How do I prepare for a G6PD test?

Ask your healthcare provider about special preparation for a G6PD test. Some medications and foods can interfere with your test results. Give your provider a list of all the medications and supplements you take. You typically don’t need to stop eating or drinking (fast) before the test.

Your healthcare provider may tell you to avoid eating fava beans or taking sulfa medications. Sulfa medications include some types of:

On the day of the test, if you’re having active symptoms of hemolytic anemia, you may need to reschedule the test. When you have symptoms, your body destroys cells that have low G6PD. As a result, the blood test may incorrectly show that you have typical G6PD levels.

What are the risks of a G6PD test?

G6PD tests are low risk. Like all blood tests, you may have some minor soreness from the needle poke. Other risks include:

  • Bruising.
  • Excessive bleeding.
  • Infection.

Most people don’t have complications from a G6PD test. Symptoms are typically mild and disappear within a day or two.

Results and Follow-Up

What should I know about the results of a G6PD test?

Low levels of G6PD can indicate a G6PD deficiency. You may have a deficiency without having hemolytic anemia. If you have a G6PD deficiency, it’s important to avoid triggers of symptoms.

Some women have slightly low G6PD without having a deficiency. These test results may mean you are a carrier of G6PD deficiency. That means you have one gene for G6PD deficiency and one gene for typical G6PD levels. Typically, you won’t have symptoms or a low red blood cell count. But you can pass a G6PD deficiency to your children.

When should I call my doctor?

Most people with a G6PD deficiency successfully manage it by avoiding triggers. Call your doctor if you have symptoms of hemolytic anemia that:

  • Are severe enough to interfere with your activities.
  • Last longer than 24 to 48 hours.

Frequently Asked Questions

Is a G6PD deficiency serious?

Not always. Many people have a G6PD deficiency that never leads to hemolytic anemia. Unless you have hemolytic symptoms, a G6PD deficiency typically won’t interfere with your usual activities.

People with hemolytic anemia need to avoid triggers that could cause hemolytic symptoms. Hemolytic symptoms can be severe and may require medical treatment.

A note from Cleveland Clinic

A G6PD test is a blood draw to check levels of glucose-6-phosphate dehydrogenase. G6PD is an enzyme that helps your red blood cells function correctly. Low G6PD can lead to a condition called hemolytic anemia. You may need a G6PD test if you have symptoms of hemolytic anemia. If you have low G6PD, your healthcare provider will give you instructions for avoiding triggers. Avoiding triggers can help you live symptom-free.

Last reviewed by a Cleveland Clinic medical professional on 02/02/2022.

References

  • National Organization for Rare Disorders. Glucose-6-Phosphate Dehydrogenase Deficiency. (https://rarediseases.org/rare-diseases/glucose-6-phosphate-dehydrogenase-deficiency/) Accessed 2/2/2022.
  • U.S. National Institutes of Health, National Library of Medicine. G6PD Test. (https://medlineplus.gov/lab-tests/g6pd-test/) Accessed 2/2/2022.

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