What is creatine kinase (CK)?
Creatine kinase (CK) is a muscle enzyme released into circulation when skeletal, cardiac, or brain muscle cells are damaged. Elevated CK most often reflects exercise or rhabdomyolysis.
Full answer
Creatine kinase (CK) is an enzyme concentrated in skeletal muscle, cardiac muscle, and brain tissue. Serum CK rises whenever those cells are injured. Common causes include intense eccentric exercise, statin-associated muscle effects, trauma, rhabdomyolysis, and rarer inherited myopathies. Mild elevations after exercise are expected and resolve within days. Marked elevations (more than 5x the upper reference limit) with muscle symptoms warrant prompt provider evaluation for rhabdomyolysis. Within oMeds review, CK is interpreted alongside symptoms, recent exercise pattern, medication context, and renal function. Baseline CK varies meaningfully by sex, muscle mass, and ethnicity; isolated mild elevations in active patients are usually benign.
Educational. Not a substitute for individualized provider review.
- CK — Primary source · oMeds
- Reviewed by Dr. Laura Purdy, MD, MBA · Clinical Director, oMeds · Last reviewed 2026-05-29