Creatine Kinase
An enzyme found mainly in muscle that leaks into blood when muscle is damaged or stressed.
| Typical reference range (male) | 44–196 U/L |
| Typical reference range (female) | 29–143 U/L |
Ranges vary by laboratory, method, age and sex: always use the range printed on your own report. Why labs differ.
What it measures
Creatine kinase helps regenerate ATP for energy in skeletal muscle, heart and brain. Blood levels rise when muscle cells are injured.
Why it matters
CK helps detect muscle injury or inflammation, statin-related muscle effects and rhabdomyolysis. It explains elevated AST and ALT when the source is muscle rather than liver.
What a high result can mean
Mild to marked rises commonly follow strenuous or unfamiliar exercise (especially eccentric lifting or long-distance running), intramuscular injections and trauma. Other causes include statins, hypothyroidism, inflammatory myopathies, muscular dystrophies, seizures and rhabdomyolysis (very high, often above 5000-10000 U/L).
What a low result can mean
Low CK is usually not significant and reflects low muscle mass.
What affects the result
Avoid hard training for 3-5 days before testing for a baseline. Levels are higher in men, people with more muscle mass and those of African ancestry. Check alongside AST, ALT and creatinine.
Units and conversion
Usually reported in U/L.
- From IU/L: multiply by 1 to get U/L
- From ukat/L: multiply by 60 to get U/L
Also called on lab reports
CK, CPK, Creatine Kinase, Total, CK, Total, Creatine Phosphokinase, CK Total
Related tests: Muscle & Bone
This page is educational and does not replace advice from a healthcare professional.