Creatine Kinase (CK)

What is Creatine Kinase?

Creatine kinase (CK) is an enzyme found primarily in skeletal muscle, heart muscle, and brain tissue. It plays a crucial role in energy production within muscle cells. When muscle cells are damaged, CK leaks into the bloodstream, making it a useful marker for muscle injury.

Why is it Tested?

Doctors order CK to evaluate muscle damage from heart attacks, muscle diseases, strenuous exercise, or medications that can cause muscle breakdown. It’s also used to monitor patients taking statins or other drugs that may cause muscle toxicity.

Normal Ranges

Reference ranges vary by gender and lab:

Men: 30–200 U/L
Women: 29–168 U/L

CK levels are typically higher in men due to greater muscle mass. Athletes and physically active individuals may have chronically elevated baseline levels.

Reference ranges vary by authority. Track yours across multiple standards with automatic unit conversions in LabsVault.

What do Abnormal Results Mean?

Abnormal results are not a diagnosis. Always discuss your results with a qualified healthcare provider before making any medical decisions.

High Creatine Kinase

Elevated levels may indicate:

Heart attack (myocardial infarction)
Muscular dystrophy or myopathy
Statin-induced muscle toxicity
Intense physical exercise
Muscle trauma or surgery

Low Creatine Kinase

Lower levels may suggest:

Decreased muscle mass
Prolonged inactivity
Advanced age
Certain autoimmune conditions

How to Track Over Time

CK levels can fluctuate dramatically with exercise, muscle injury, and medications. Establishing a personal baseline helps identify significant changes. For patients on statins, regular monitoring detects muscle toxicity before symptoms develop, allowing for medication adjustments.

Creatine Kinase