G6PD screen
Key points
- The RBC G6PD test measures the amount (activity) of the enzyme G6PD in red blood cells.
- Blood is drawn from a vein, usually from the inside of the elbow or the back of the hand.
- The area is cleaned with antiseptic and punctured with a sharp needle or a lancet.
- The preparation you can provide for this test depends on your child's age, previous experiences, and level of trust.
Alternative names
RBC G6PD test; Glucose-6-phosphate dehydrogenase
Definition
The RBC G6PD test measures the amount (activity) of the enzyme G6PD in red blood cells.
How the test is performed
Blood is drawn from a vein, usually from the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic, and a tourniquet is placed around the upper arm to apply pressure and restrict blood flow through the vein. This causes veins below the tourniquet to fill with blood.
A needle is inserted into the vein, and the blood is collected in an air-tight vial or a syringe. During the procedure, the tourniquet is removed to restore circulation. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.
Infant or young child:
The area is cleaned with antiseptic and punctured with a sharp needle or a lancet. The blood may be collected in a pipette (small glass tube), on a slide, onto a test strip, or into a small container. A bandage may be applied to the puncture site if there is any continued bleeding.
How to prepare for the test
No special preparation is usually necessary.
Infants and children:
The preparation you can provide for this test depends on your child's age, previous experiences, and level of trust. For specific information regarding how you can prepare your child, see the following:
- Infant test or procedure preparation (birth to 1 year)
- Toddler test or procedure preparation (1 to 3 years)
- Preschooler test or procedure preparation (3 to 6 years)
- Schoolage test or procedure preparation (6 to 12 years)
- Adolescent test or procedure preparation (12 to 18 years)
How the test will feel
When the needle is inserted to draw blood, some people feel moderate pain, while others feel only a prick or stinging sensation. Afterward, there may be some throbbing.
Why the test is performed
This test is performed when the diagnosis of G6PD deficiency is suspected.
Red blood cells are almost solely dependent on blood glucose as a source of energy. This biochemical pathway is called glycolysis. Red blood cells can also divert glucose into a secondary pathway which results in the production of NADPH from NADP (nicotinamide adenine dinucleotide phosphate).
Written and revised by
David Cohen, M.D.
Our doctors write and review articles for accuracy and keep them up to date.
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