Cardiac-specific troponin-I radioimmunoassay in the diagnosis of acute myocardial infarction

Am Heart J. 1987 Jun;113(6):1333-44. doi: 10.1016/0002-8703(87)90645-4.


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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • Adult
  • Aged
  • Chest Pain / metabolism
  • Coronary Disease / metabolism
  • Creatine Kinase / metabolism
  • Female
  • Humans
  • Immune Sera / immunology
  • Male
  • Middle Aged
  • Myocardial Infarction / diagnosis*
  • Myocardial Infarction / enzymology
  • Myocardial Infarction / metabolism
  • Myocardium / metabolism*
  • Organ Specificity
  • Radioimmunoassay / standards*
  • Reference Values
  • Troponin / metabolism*
  • Troponin I


  • Immune Sera
  • Troponin
  • Troponin I
  • Creatine Kinase