Macrocreatincinasa tipo 1 como causa de aumento de la isoenzima CK-MB. A propósito de 7 casos

Abstract

The macro-creatine kinase type 1 is a complex of IgG linked to the BB fraction of the creatine kinase enzyme. Its presence in serum interferes with the immunoinhibition methods normally used in emergency room laboratories that produce false elevations of the creatine kinase MB isoenzyme, and which may cause a misunderstanding in the evaluation of patients who are suspected of having ischemic cardiopathy. We have studied seven patients using an immunoinhibition method. They showed high levels of creatine kinase MB isoenzyme with normal values of creatine kinase enzyme. Electrophoresis was performed on all patients to determine the presence of creatine kinase enzyme. The electrophoresis showed in all the cases the presence of a macro-creatine kinase type 1 responsible for this interference. The clinical and analytical evaluation, as well as the radiological and electrocardiographical evaluation of this patients did not show any acute coronary disease. The macro-creatine kinase type 1 has been related to the existence of underlying cardiovascular pathology; a fact that was confirmed in three patients. With the immunoinhibition methods, the macro-creatine kinases usually, occurs with high values of creatine kinase MB isoenzyme (normally above 50% of the total activity of the creatine kinase) with normal creatine kinase levels. This fact, although strongly suggesting its presence, creates the necessity of using more sensitive methods to prevent these interferences. Likewise, we recommend using the electrophoresis of the creatine kinase enzyme to determine the nature of these interferences.