Pyruvate kinase |
| Definition: |
| Pyruvate kinase (PK) is an enzyme that helps in the conversion of glucose to energy when there is not adequate oxygen (termed anaerobicmetabolism). This enzyme is located within red blood cells, and if it is deficient, red bloods cells break down more rapidly than usual (hemolysis). This can result in a decrease in the number of oxygen-carrying red blood cells in the blood (also known as hemolytic anemia). This test determines whether there is an abnormally low level of the pyruvate kinase enzyme. |
| Alternative Names: |
| PK |
| How the test is performed: |
| Blood is drawn from a vein (venipuncture), usually from the inside of the elbow or the back of the hand. The puncture site is cleaned with antiseptic, and a tourniquet (an elastic band) or blood pressure cuff is placed around the upper arm to apply pressure and restrict blood flow through the vein. This causes veins below the tourniquet to distend (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. In the laboratory white blood cells are removed, since they can alter test results, and the level of pyruvate kinase is analyzed. |
| How to prepare for the test: |
| If your child is to have this test performed it may be helpful to explain how the test will feel, and even practice or demonstrate on a doll. The more familiar your child is with what will happen to them, and the purpose for the procedure, the less anxiety they will feel. |
| 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: |
| Hemolytic anemia has many causes that may be congenital (i.e., genetic and present from birth) or acquired. A deficiency in pyruvate kinase is fairly rare, and this test helps your health care provider differentiate the cause of your anemia. |
| Normal Values: |
|
The Pyruvate kinase level is measured in relation to the amount of hemoglobin (a normal constituent of red blood cells) in the sample. The results vary depending upon the testing method used. The laboratory performing the test should be consulted for the range of values seen in healthy individuals. |
| What abnormal results mean: |
| Low levels of pyruvate kinase confirm pyruvate kinase deficiency. Your health care provider can also distinguish between anemia caused by pyruvate kinase deficiency and other inherited disorders. |
| What the risks are: |
| Risks associated with venipuncture are slight: |
| Special considerations: |
| 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. |
Reviewed By: Michael C. Milone, M.D., Ph.D., Department of Pathology and Laboratory Medicine, University of Pennsylvania Medical Center, Philadelphia, PA. Review provided by VeriMed Healthcare Network.
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