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.

A blood sample is needed. For information on how this is done, see: Venipuncture

In the laboratory, white blood cells are removed because they can alter test results. The level of pyruvate kinase is then measured.

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.

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.

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)

Results vary depending upon the testing method used. In general, a normal value is 179 ± 16 units per 100mL of red blood cells.

Normal value ranges may vary slightly among different laboratories. Talk to your doctor about the meaning of your specific test results.

The examples above show the common measurements for results for these tests. Some laboratories use different measurements or may test different specimens.

Low levels confirm pyruvate kinase deficiency.

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:

• Excessive bleeding
• Fainting or feeling light-headed
• Hematoma (blood accumulating under the skin)
• Infection (a slight risk any time the skin is broken)

Gallagher PG. Hemolytic anemias:  red cell membrane and metabolic defects In: Goldman L, Schafer AI, eds. Cecil Medicine. 24th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 164.

Ginder GD. Microcytic and hypochromic anemias. In: Goldman L, Schafer AI, eds. Cecil Medicine. 24th ed. Philadelphia, Pa: Saunders Elsevier; 2011:chap 162.

Gregg X, Prchal JT. Red Blood Cell Enzymopathies. In: Hoffman R, Benz EJ, Shattil SS, et al, eds. Hematology: Basic Principles and Practice. 5th ed. Philadelphia, Pa: Elsevier Churchill Livingstone; 2008:chap 45.

Yee DL, Bollard CM, Geaghan SM. Appendix: Normal Blood Values. In: Hoffman R, Benz EJ, Shattil SS, et al, eds. Hematology: Basic Principles and Practice. 5th ed. Philadelphia, Pa: Elsevier Churchill Livingstone; 2008:chap 164.