Creatine kinase isoenzymes in serum from children-especially focusing on CK-BB

In 161 children with ages ranging from 7 months to 18 years the concentration of CK-BB in serum was measurable in 58%. The activity in serum of CK-BB (cCK-BB(S)) in children varies with age and is not significantly influenced by seizure, epilepsy or body temperature. The values are most elevated during the first year of life and show a rapid fall, never reaching adult levels. Comparing mean cCK-BB(S) values in children to growth charts the resemblance is striking. CK-BB is the only CK-isoenzyme that changes with age. We postulate that cCK-BB(S) is related to growth as a physiological phenomenon. CK-MB was found in serum in 7% of the children and could not be of cardiac origin. Therefore CK-MB cannot be regarded as cardiac specific in children.