[Separation and assay of the MB isoenzyme of serum creatine phosphokinase. Results apropos of 152 cases]. / Séparation et dosage de l'iso-enzyme MB de la créatine phosphokinase sérique. Résultats à propos de 152 observations

MB iso-enzyme of creatine phosphokinase (CPK) was estimated after chromatography. The technique used, Mercer's technique, was simple and rapid. It required 1 ml of serum. The study carried out in 152 subjects showed that CPK was increased (N less than 90 mU/ml). In the group of 104 patients with myocardial infarction (average CPK levels = 829 mU/ml +/- 516), the MB iso-enzyme was found in the serum in significant levels (average level of the MB fraction = 10.9% +/- 5.4). On the other hand, in the control group of 44 patients with various diseases, (CPK = 672 mU/ml +/- 531) the MB iso-enzyme remained low (0.35% +/- 0.44). In two subjects with myocardial infarction, no MB fraction was found. On the other hand, in two patients who died, one from necrotic, prostatic adenocarcinoma, the other from necrotic epidermoid lung cancer, the MB iso-enzyme was significantly increased. The test proposed here, which is applicable in a routine laboratory, seems the most specific of all laboratory examinations available to the clinician for the diagnosis of myocardial infarction.

[Isoenzyme distribution of creatine kinase in various human organs. Interest in human pathology (author's transl)]. / Répartition isozymique de la créatine kinase dans différents organes humains. Intérêt en pathologie humaine.

The isoenzyme content of creatine kinase was determined in various human organs after autopsy. The results found were on the whole in agreement with the literature. Their analysis dictates the choice of a method of separation of the MB fraction: chromatography or electrophoresis. It permits better interpretation of the results of estimation of the MB fraction in the serum.

[The MB Iso-enzyme of creatine phosphokinase in myocardial infarction (author's transl)]. / L'iso-enzyme MB de la créatine phosphokinase dans l'infarctus du myocarde.

CPK and its MB iso-enzymatic fraction were measured in 240 patients, 180 of whom suffered from myocardial infarction. MB iso-enzyme was expressed as a percentage of total CPK and a minimum figure of 4 per cent of MB isoenzyme was taken as indicative of a diagnosis of myocardial infarction. In the 180 patients with an infarction, the average MB level as a percentage of total CPK was 12.1 +/- 5.4 per cent. Five patients with a proven infarct had an MB iso-enzyme level of less than 4 per cent. Amongst the 60 patients without a myocardial infarction who were included in view of a pathological level of CPK, the average maximum level of MB was 1 +/- 2.5 per cent. Five of these 60 patients (false positives: 8.3%) had an MB iso-enzyme level of greater than 4 per cent. It is concluded that the estimation of MB iso-enzyme of CPK using a chromatographic technic is a highly valuable laboratory method for confirming or eliminating a diagnosis of myocardial infarction in the numerous clinical circumstances when such a diagnosis is difficult or even impossible on the basis of standard data.