[Macro creatine kinase type 1 as a cause of increase of CF-MB isoenzyme. Apropos of 7 cases]. / Macrocreatincinasa tipo 1 como causa de aumento de la isoenzima CK-MB. A propósito de 7 casos.

INTRODUCTION: 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. PATIENTS AND METHOD: 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. RESULTS: 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. CONCLUSIONS: 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.

Prospective evaluation of fever of unknown origin in patients infected with the human immunodeficiency virus. Grupo Andaluz para el Estudio de las Enfermedades Infecciosas.

The aim of this study was to determine the frequency and aetiology of fever of unknown origin (FUO) in patients infected with the human immunodeficiency virus (HIV), to assess the value of the tests used in its diagnosis, and to evaluate possible models of diagnosis for the causes found most frequently. One hundred twenty-eight (3.5%) of 3603 hospitalised HIV-positive patients evaluated from October 1992 to December 1993 had FUO, defined by established criteria. Eighty-six percent of patients with FUO had previously progressed to AIDS. The median CD4+ cell count was 46/mm3. A definite diagnosis was made in 96 (75%) of the 128 patients and a possible diagnosis in 24 (18.7%). whilst no diagnosis was made in eight cases (6.2%). Tuberculosis (48.3%), visceral leishmaniasis (16%), and infection by Mycobacterium avium complex (6.9%) were the diseases found most frequently. The most useful diagnostic tests were liver biopsy (68.9%) and bone marrow aspirate/biopsy (39.7%). It is not possible to predict clinically the cases of FUO due to tuberculosis, whilst thrombocytopaenia < 100,000 cells/mm3 alone is useful for differentiating the cases of visceral leishmaniasis, with a negative predictive value of 95.2%.