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Definition Return to top
Pyruvate kinase is an enzyme found in red blood cells that helps change sugar in the blood (glucose) to energy when oxygen levels are low.
This article discusses the test to measure the level of pyruvate kinase in your blood.
How the Test is Performed Return to top
Blood is typically drawn from a vein, usually from the inside of the elbow or the back of the hand. The site is cleaned with germ-killing medicine (antiseptic). The health care provider wraps an elastic band around the upper arm to apply pressure to the area and make the vein swell with blood.
Next, the health care provider gently inserts a needle into the vein. The blood collects into an airtight vial or tube attached to the needle. The elastic band is removed from your arm. Once the blood has been collected, the needle is removed, and the puncture site is covered to stop any bleeding.
In infants or young children, a sharp tool called a lancet may be used to puncture the skin and make it bleed. The blood collects into a small glass tube called a pipette, or onto a slide or test strip. A bandage may be placed over the area if there is any bleeding.
In the laboratory, white blood cells are removed because they can alter test results. The level of pyruvate kinase is then measured.
How to Prepare for the Test Return to top
If your child is to have this test performed, it may be helpful to explain how the test will feel, and even demonstrate on a doll. Explain the reason for the test. Knowing the "how and why" may reduce the anxiety your child feels.
How the Test Will Feel Return to top
When the needle is inserted to draw blood, you may feel moderate pain, or only a prick or stinging sensation. Afterwards, there may be some throbbing.
Why the Test is Performed Return to top
This test is done to detect abnormally low levels of pyruvate kinase. If you do not have enough of this enzyme, red blood cells break down faster than normal. This can lead to hemolytic anemia, which is a low red blood cell count caused by an accelerated destruction of red blood cells.
See also: Pyruvate kinase deficiency (PKD)
Normal Results Return to top
Results vary depending upon the testing method used.
Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.
What Abnormal Results Mean Return to top
Low levels confirm pyruvate kinase deficiency.
Risks Return to top
Veins and arteries vary in size from one patient to another and from one side of the body to the other. Obtaining a blood sample from some people may be more difficult than from others.
Other risks associated with having blood drawn are slight but may include:
References Return to top
Golan DE. Hemolytic anemias: red cell membrane and metabolic defects. In: Goldman L, Ausiello D, eds. Cecil Medicine. 23rd ed. Philadelphia, Pa: Saunders Elsevier;2007:chap 165.Update Date: 11/23/2008 Updated by: David C. Dugdale, III, MD, Professor of Medicine, Division of General Medicine, Department of Medicine, University of Washington School of Medicine; and Yi-Bin Chen, MD, Leukemia/Bone Marrow Transplant Program, Massachusetts General Hospital. Also reviewed by David Zieve, MD, MHA, Medical Director, A.D.A.M., Inc.