Creatine kinase
Key points
- A CPK is a blood test that measures creatine phosphokinase (CPK), an enzyme found predominantly in the heart, brain, and skeletal muscle.
- Blood is drawn from a vein, usually from the inside of the elbow or the back of the hand.
- The area is cleansed with antiseptic and punctured with a sharp needle or a lancet.
- The physical and psychological preparation a parent can provide for this or any test or procedure depends on the child's age, interests, previous experiences, and level of trust.
Alternative names
CK; CPK; Creatine phosphokinase
Definition
A CPK is a blood test that measures creatine phosphokinase (CPK), an enzyme found predominantly in the heart, brain, and skeletal muscle. When the total CPK level is substantially elevated, it usually indicates injury or stress to one or more of these areas.
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 (an elastic band) or blood pressure cuff is placed around the upper arm to apply pressure and cause veins below the tourniquet to distend (fill with blood).
A needle is inserted into the vein, and the blood is collected in an airtight 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.
This test may be repeated over 2 or 3 days for a hospitalized patient. The pattern of a rise or fall in CPK (or CPK isoenzymes) can be diagnostically significant.
Infant or young child:
The area is cleansed 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. Cotton or a bandage may be applied to the puncture site if there is any continued bleeding.
How to prepare for the test
Usually, no special preparation is necessary.
Infants and children:
The physical and psychological preparation a parent can provide for this or any test or procedure depends on the child's age, interests, previous experiences, and level of trust. For specific information regarding how you can prepare your child, see the following topics as they correspond to your child's age:
- 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 may feel moderate pain, while others may feel only a prick or stinging sensation. Afterward, there may be some throbbing.
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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