Creatine Kinase (CK)

Creatine phosphokinase (CPK).

• To diagnose muscle disorders and monitor their course.
• To help verify a suspected heart attack.
• To identify female carriers of Duchenne muscular dystrophy, although more accurate genetic tests are now available for detecting this disorder.

Creatine kinase (CK) is an enzyme present in skeletal muscle, heart muscle, and the brain. When muscle is damaged or diseased, CK flows into the bloodstream, where it can be measured.

Avoid exercise and strenuous physical activity for three or four hours before the test.

Blood is drawn from a vein in your arm and sent to a laboratory for analysis.

You follow standard procedures for venipuncture and are free to leave.

• Exercise or strenuous physical activity within the previous 24 hours.
• Surgery that involved incision through muscle.
• Intramuscular injections.

Increased CK levels may signal muscular dystrophy, polymyositis, dermatomyositis, and sometimes myositis, as well as heart attack. CK may also be elevated after surgery, or in some people with underactive thyroid gland or malignant hyperthermia, an abnormally high fever that develops in response to certain anesthetics. CKs increase with exercise. It is important that this test not be done following significant exercise.

It's noninvasive.

It detects an abnormality but not its cause.

An abnormal CK level in itself cannot diagnose a muscle disorder. Therefore, additional tests must be ordered, depending on the patient's history and symptoms. These might include an electromyogram and a muscle biopsy.