Cardiac-specific troponin-I radioimmunoassay in the diagnosis of acute myocardial infarction.
The cardiac isotype of the myofibrillar contractile protein, troponin-I, is located specifically in the mammalian heart. A sensitive radioimmunoassay has been developed to detect human and nonhuman primate cardiac troponin-I in serum down to 10 ng/ml. Immunochemical cross reactivity with skeletal troponin-I was only 2% and was species nonspecific. Normal patient levels of cardiac troponin-I are about 10 ng/ml. In patients with acute myocardial infarction (n = 32), serum cardiac troponin-I was elevated within 4 to 6 hours, reached a mean peak level of 112 ng/ml (range 20 to 550 ng/ml) at 18 hours, and remained above normal for up to 6 to 8 days following infarction. Peak cardiac troponin-I correlated with peak creatine kinase (CK) MB isoenzyme (r = 0.75). In subjects (n = 34) with skeletal muscle damage (total CK = 338 to 5384 IU/L), cardiac troponin-I levels were not elevated above normal, although CK-MB isoenzyme was elevated in some patients. Cardiac troponin-I levels were normal or slightly elevated in patients with ischemic heart disease and were normal in patients with chest pain of noncardiac origin. Immunoassay of cardiac troponin-I could be a valuable diagnostic aid in the cardiac-specific detection of cell necrosis.
D000328:Adult; D000368:Aged; D002637:Chest Pain / Q000378:metabolism; D003327:Coronary Disease / Q000378:metabolism; D003402:Creatine Kinase / Q000378:metabolism; D005260:Female; D006801:Humans; D007106:Immune Sera / Q000276:immunology; D008297:Male; D008875:Middle Aged; D009203:Myocardial Infarction / Q000175:diagnosis* / Q000201:enzymology / Q000378:metabolism; D009206:Myocardium / Q000378:metabolism*; D009928:Organ Specificity; D011863:Radioimmunoassay / Q000592:standards*; D012016:Reference Values; D014336:Troponin / Q000378:metabolism*; D019210:Troponin I
D007106:Immune Sera; D014336:Troponin; D019210:Troponin I; D003402:Creatine Kinase