Differentiating muscle damage from myocardial injury by means of the serum creatine kinase (CK) isoenzyme MB mass measurement/total CK activity ratio.
We immunoenzymometrically measured creatine kinase (CK) isoenzyme MB in extracts of myocardium and in homogenates of five different skeletal muscles. CK-MB concentrations in the former averaged 80.9 micrograms/g wet tissue; in the skeletal muscles it varied widely, being (e.g.) 25-fold greater in diaphragm than in psoas. CK-MB in skeletal muscles ranged from 0.9 to 44 ng/U of total CK; the mean for myocardium was 202 ng/U. In sera from 10 trauma and 36 burn patients without myocardial involvement, maximum ratios for CK-MB mass/total CK activity averaged 7 (SEM 1) ng/U and 18 (SEM 6) ng/U, respectively. Except for an infant (220 ng/U), the highest ratio we found for serum after muscular damage was 38 ng/U. In contrast, the mean maximum ratio determined in 23 cases of acute myocardial infarction exceeded 200 ng/U. Among seven determinations performed 8 to 32 h after onset of symptoms, each infarct patient demonstrated at least one ratio greater than or equal to 110 ng/U. Ratios observed after infarct were unrelated to treatment received during the acute phase. We propose a CK-MB/total CK ratio of 80 ng/U as the cutoff value for differentiating myocardial necrosis from muscular injury.
D000063:Accidents, Traffic; D000328:Adult; D000368:Aged; D001344:Autopsy; D002056:Burns / Q000201:enzymology*; D002675:Child, Preschool; D003402:Creatine Kinase / Q000032:analysis*; D005260:Female; D006801:Humans; D007124:Immunoenzyme Techniques; D007223:Infant; D007527:Isoenzymes; D008297:Male; D008875:Middle Aged; D009132:Muscles / Q000201:enzymology / Q000293:injuries*; D009203:Myocardial Infarction / Q000188:drug therapy / Q000201:enzymology*; D009206:Myocardium / Q000201:enzymology; D013056:Spectrophotometry, Ultraviolet; D013997:Time Factors
D007527:Isoenzymes; D003402:Creatine Kinase