Elevated Atypical Creatine Kinases

Abstract

To the Editor.— We read with interest the CASE REPORT by Gibson and Schnur 1 concerning an atypical creatine kinase (CK) in a patient with adenocarcinoma of the lung. The CK profile was unusual in that there was a persistent intermediately migrating electrophoretic band that was initially confused with CK-MB and accounted for the majority of the CK activity. We wish to offer two possible explanations for the atypical CK observed by Gibson and Schnur that coincide with our experimental observations. Macro CK type 1 is a term used to designate some atypical electrophoretic CK bands occasionally found migrating between CK-MM and CK-MB. Macro CK type 1 is composed of a CK isoenzyme, usually CK-BB or possibly CK-MM, complexed to another serum protein. The isoenzyme is usually complexed with IgG, but IgA and β-lipoprotein complexes have also been identified. We have found that the addition of antiserum to CK-BB to