Creatine Kinase Activity in Cerebrospinal Fluid-Reply

In Reply.  —Increased activity in cerebrospinal fluid (CSF) of creatine kinase (CK) or of its more brain-specific BB isoenzyme (CK-BB) now appears to reliably indicate brain damage after brain ischemia^1,2 and head trauma^3,4 and possibly also after stroke.⁵ Unfortunately, the clinical use of CK and CK-BB measurements has been, and to some extent still is, hampered by technical difficulties. Some of these problems have been discussed previously.^6,7 Chandler and coworkers focus on two of the more important ones: the use of a reactivator and the possible presence in CSF of mitochondrial CK (CK-mt) in addition to the cytoplasmic forms.Creatine kinase is rapidly inactivated in serum and CSF but is reactivated prior to assay with the use of an SH-compound, which is a reactivator that is now included in all commercial CK reagents. We use reagents containing N-acetylcysteine (NAC) as a reactivator. Dithiothreitol (DTT) is a