Identification of false-positive CK-MB activity in an elderly patient

An unusual occurrence of an aberrant CK-MB activity in an elderly female patient is described. The CK-MB-like activity present in serum samples from this patient was definitively identified as an immunoglobulin A complex of CK-MM (macro CK, type 1) using CK isoenzyme agarose gel electrophoresis after pretreating the patient's serum sample with either anti-immunoglobulin A antiserum or anti-CK-M antibody reagent.