Pyruvate kinase blood test

Definition

The pyruvate kinase test measures the level of the enzyme pyruvate kinase in the blood.

Pyruvate kinase is an enzyme found in red blood cells. It helps change sugar in the blood (glucose) to energy when oxygen levels are low.

How the Test is Performed

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

How to Prepare for the Test

No special preparation is necessary.

If your child is having this test, it may help 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 your child's anxiety.

How the Test will Feel

When the needle is inserted to draw blood, some people feel moderate pain. Others feel only a prick or stinging. Afterward, there may be some throbbing or a slight bruise. This soon goes away.

Why the Test is Performed

This test is done to detect an abnormally low level of pyruvate kinase. Without enough of this enzyme, red blood cells break down faster than normal. This is called hemolytic anemia.

This test helps diagnose pyruvate kinase deficiency (PKD).

Normal Results

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

Normal value ranges may vary slightly among different laboratories. Some labs use different measurements or test different samples. Talk to your health care provider about the meaning of your specific test results.

What Abnormal Results Mean

A low level of pyruvate kinase confirms PKD.

Risks

There is little risk involved with having your blood taken. Veins and arteries vary in size from one person to another and from one side of the body to the other. Taking blood 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 lightheaded
• Multiple punctures to locate veins 
• Hematoma (blood buildup under the skin)
• Infection (a slight risk any time the skin is broken) 

References

Gallagher PG. Hemolytic anemias: red cell membrane and metabolic defects. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 25th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 161.

van Solinge WW, van Wijk R. Enzymes of the red blood cell. In: Rifai N, ed. Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. 6th ed. Philadelphia, PA: Elsevier; 2018:chap 30.