Creatine kinase (CK) is an enzyme that catalyzes the reversible phosphorylation of creatine (Cr) by adenosine triphosphate (ATP). CK activity is greatest in striated muscle (MM isoenzyme ), heart tissue (MB isoenzyme ), and brain (BB isoenzyme ). Serum CK concentrations are reflective of muscle mass causing males to have higher concentrations than females.
This test id used for diagnosing and monitoring myopathies or other trauma, toxin, or drug-induced muscle injury.
Reference Values
Males
< or =3 months: not established
>3 months: 39-308 U/L
Females
< or =3 months: not established
>3 months: 26-192 U/L
