Creatine Phosphokinase Test
The creatine phosphokinase test measures the amount of creatine phosphokinase (CPK) present in the blood. The test is also known as creatine kinase, CPK test, and CK test.
Creatine phosphokinase is a specific enzyme found primarily in the heart, skeletal muscle, and brain.
The creatine phosphokinase test is performed to assess damage to tissue in the brain, muscle tissue, or heart. When tissue is damaged, creatine phosphokinase leaks from tissue into the blood.
The test is used to diagnose and evaluate the following conditions:
- heart attack
- chest pain
- muscle damage
- early dermatomyositis (a muscle and connective-tissue disease)
- polymyositis (results in inflammation of the muscles)
- differentiate between postoperative infection and malignant hyperthermia (a fast rise in body temperature)
- gene associated with muscular dystrophy
How Is the Creatine Phosphokinase Test Performed?
The creatine phosphokinase test is performed through a blood test. The blood sample is taken by a health professional, usually with the following steps:
- The flow of blood is stopped by wrapping an elastic band around your upper arm. This also causes the veins in your arm to become more visible, so the needle can be more easily inserted.
- Alcohol is used to clean the site on your skin where the needle will be inserted.
- The needle is inserted into the vein. This may cause a brief pinching or stinging sensation, or you may not feel anything at all.
- Blood is collected by attaching a tube to the needle. Sometimes more than one tube may be needed.
- The elastic band is removed after enough blood has been collected.
- As the needle is removed from the skin, cotton or gauze is placed on the site of the injection.
- Pressure is applied to the area and a bandage is used to secure the cotton or gauze.
As the needle is inserted into the vein you may feel a stinging or pinching sensation, mild discomfort, or you may feel nothing at all.
After the blood has been collected, the sample is sent to a lab, so the level of creatine phosphokinase in the blood can be measured. If you are an inpatient in the hospital, the test may be repeated over a few days.
Risks Associated with the Creatine Phosphokinase Test
There is little risk associated with having a blood test. Since the test involves a needle being inserted into a vein, there may be some mild bruising. After the needle is removed from the vein, the risk of bruising can be minimized by applying pressure to the needle site with a sterile pad, cotton ball, or warm compress for several minutes.
In very rare cases, the following may occur when having blood drawn from a vein:
- excessive bleeding
- hematoma, or the accumulation of blood beneath the skin
- lightheadedness or fainting
Preparation for the Creatine Phosphokinase Test
There are usually no specific preparations needed before the creatine phosphokinase test. Be sure to make your doctor aware of medications you may be taking, as there are certain drugs that can affect the results of the test. These medications include:
- some anesthetics
- amphotericin B
Results of the Creatine Phosphokinase Test
When high levels of creatine phosphokinase are detected in the blood, it is considered to be an abnormal result. High levels of the enzyme may occur due to the following conditions:
- heart attack
- pericarditis after a heart attack
- polymyositis or dermamyositis
- heart muscle inflammation
- myopathy (a disease of the muscles)
- rhabdomyolysis (a breakdown of muscle tissues)
- muscular dystrophies
- electric shock
- brain injury
- delirium tremens (caused by alcohol withdrawal)
- hypothyroidism (a decrease in the activity of the thyroid gland) or hyperthyroidism (an increase in activity of the thyroid gland)
- death of lung tissue