MACRO-CREATINE-KINASE TYPE-1 AS A CAUSE O F CREATINE-KINASE-MB ISOENZYME ELEVATION - REPORT OF 7 CASES

Introduction. The macro-creatine kinase type 1 is a complex of IgG lin ked to the BE fraction of the creatine kinase enzyme. Its presence in serum interferes with the immunoinhibition methods normally used in em ergency room laboratories that produce false elevations of the creatin e kinase MB isoenzyme, and wich mag cause a misunderstanding in the ev aluation of patients who are suspected of having isquemic cardiopathy. Patients and method. We have studied seven patients using an immunoin hibition method. They showed high levels of creatine kinase MB isoenzy me with normal values of creatine kinase enzyme. Electrophoresis was p erformed on all patients to determine the presence of creatine kinase enzyme. Results. The electrophoresis showed in all the cases the prese nce of a macro-creatine kinase type 1 responsible for this interferenc e. The clinical and analytical evaluation, as well as the radiological and electrocardiographical evaluation of this patients, did not show any acute coronary disease. Conclusions. The macro-creatine kinase typ e 1 has been related to the existence of underlying cardiovascular pat hology; a fact that was confirmed in three patients. With the immunoin hibition methods, the macro-creatine kinases usually occurs with high values of creatine kinase MB isoenzyme (normally above 50% of the tota l activity of the creatine kinase) with normal creatine kinase levels. This fact, although strongly suggesting its presence, creates the nec essity of using more sensitive methods to prevent these interferences. Likiwise, we recommend using the electrophoresis of the creatine kina se enzyme to determine the nature of these interferences.