Troponin T Rapid Test Kit (Colloidal Gold Assay) is an in vitro diagnostic test for the qualitative detection of troponin T in human whole blood (venous and fingerstick) specimen. Cardiac troponin T (cTnT) is a contractile protein present in the myocardium. It is one of three subunits of the troponin complex (I, T, C), a protein that regulates striated muscle contraction. cTnT in myocardium (layer) is not the same as TnT in skeletal muscle.