Contributed by – Healthians Team
What is the CPK test?
The CPK test measures the amount of creatine phosphokinase in the blood. Creatine phosphokinase (also called creatine kinase, CK, or CPK) is an enzyme that is found in the heart, brain, skeletal muscle, and some other tissues. Having small amounts of CPK in the blood is normal. It usually comes from skeletal muscles. But its level can increase in case of any condition that causes muscle damage and interferes with muscle energy production.
Who should get tested?
A doctor may order a CPK test when muscle damage is suspected or at regular intervals to monitor continued damage. Having the following symptoms usually indicates muscle injury:
- Muscle aches and pains
- Muscle weakness
- Dark coloured urine
Why is the CPK test needed?
A CPK test, by measuring the levels of creatine phosphokinase in the blood, helps in the detection of inflammation of muscles or muscle damage due to disorders. Various other blood tests such as electrolytes, BUN, or creatinine may also be ordered along with this test.
Typically, a CPK test is used to diagnose the following conditions:
- Inflammation of the muscles; called myositis
- Muscle damage due to muscle disorders such as dystrophy
- Rapid breakdown of muscle tissues; called rhabdomyolysis
In case symptoms like fever, weakness, and nausea are present, a healthcare practitioner may use this test to understand if the symptoms are due to muscle damage or some other condition especially in the case of those who have been exposed to a known toxin that is linked with potential muscle damage.
To see whether the problem has resolved or is continuing, a series of CPK tests may be ordered. In case the location of the muscle damage is not clear, further testing may be required.
What does CPK test results mean?
CPK test normal range differs from male to female. Besides, each lab may also have its own reference range. Therefore, the CPK test results from different labs may vary. Nevertheless, the following values are often used as reference:
Male – 21 – 232 IU/L
Female – 21 – 215 IU/L
If the test results show normal values, it may indicate that there has been no muscle damage or it occurred several days before the testing.
Having high CPK values may have various causes. They can be:
- Recent muscle injuries, trauma, burns, or electrocution
- Inherited myopathies
- Hormonal disorders
- Strenuous exercise
- Prolonged surgeries
- Seizures
- Infections
- Connective tissue disorders
- Celiac disease
- Renal failure
- High fever
- Blood clot
- Drug or toxin exposure
How is the test done?
A CPK test is a normal blood test that doesn’t require fasting prior to the sample collection or any other kind of special preparation. For the testing, a small amount of blood is required which is usually drawn from a vein in the arm. The process is simple, quick, and relatively painless. At most, you may feel a prick of the needle. After an adequate amount of blood is collected and the needle is removed, a bandage is placed over the punctured site to prevent any infection. The collected sample is then sent to a lab for testing.
