The Role of Troponin And Use of Troponin Assays

Abstract

Troponin is a crucial protein present in various muscle types, including cardiac muscle (myocardium), and plays an essential role in muscle contraction, facilitating the heartbeat. Normally, only minimal levels of troponin are found in the blood. However, when myocardial injury occurs, cardiac troponin (cTn) is released into the bloodstream from the heart muscle. Monoclonal antibodies specific to cTn have enabled the development of assays for measuring cTn levels in the blood. The amount of troponin released is proportional to the severity of heart damage. During a heart attack, the heart muscle's lack of oxygen-rich blood causes damage and the subsequent release of troponin into the bloodstream.

There are three types of troponin: Troponin I (TnI), Troponin T (TnT), and Troponin C (TnC). Only TnI and TnT are used for diagnosing heart attacks because TnC cannot be identified as originating specifically from the heart muscle. Normal blood troponin levels are very low, typically between 0-0.04 nanograms per milliliter, which were difficult to measure accurately with initial tests. The advent of the high-sensitivity cardiac troponin test (hs-cTnT) now allows for detecting low levels of cardiac troponin, enabling earlier and more accurate diagnosis of heart attacks.

Troponin I can be analyzed using various methods such as Enzyme-Linked Immunosorbent Assay (ELISA), Enzyme-Linked Fluorescent Assay (ELFA), Radioimmunoassay (RIA), Fluorescence Immunoassay, and Immuno chromatography (ICT). Plasma troponin T levels can be measured using ELISA based on the Biotin-Streptavidin principle and qualitative TnT examination by immunoassay (TnT-RA). High-sensitivity troponin T (hs-TnT) and high-sensitivity troponin I (hs-cTnI) are measured using the Electro chemiluminescence Immunoassay (ECLIA) method.