The significance of total creatine kinase activity and isozyme determinations in cerebrospinal fluid of neurological patients

Total CK activity is often increased in cerebrospinal fluid samples in neurological diseases (35%). These increased levels are frequently caused by CK M-chain activity and appear to have no diagnostic relevance. Furthermore, an obvious concentration gradient for total CK activity was often observed in two subsequent tubes from the same lumbar puncture. In this study, CK non-M activity is measured, being the sum of all CK activity not caused by the M-chain. A bioluminescence technique using anti-M-inhibiting antibodies was used for this purpose. In two subsequent tubes from the same lumbar puncture a difference of 8% in CK non-M activity was found. A similar gradient could be observed for total protein. Retrospectively, the correlation between CK non-M levels and the amount of brain tissue damage was studied in 81 neurological patients and in 19 healthy subjects. There was an obvious relation between the extent of brain tissue damage and the CSF CK non-M levels. The clinical results in this study are promising and justify a prospective study of the diagnostic relevance of this parameter in CSF in various patient groups.