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Troponin T in the blood
Last reviewed: 05.07.2025
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Reference values (norm) for troponin T concentration in blood serum are 0-0.1 ng/ml.
The troponin complex is part of the contractile system of muscles. It is formed by three proteins: troponin T, which forms a bond with tropomyosin (molecular weight 3700), troponin I (molecular weight 26,500), which can inhibit ATPase activity, and troponin C (molecular weight 18,000), which has a significant affinity for Ca 2+. Approximately 93% of troponin T is contained in the contractile apparatus of myocytes; this fraction can be a precursor for the synthesis of the troponin complex, 7% - in the cytosol (which explains the biphasic peak of the increase in troponin concentration in myocardial infarction). Troponin T from cardiac muscle differs in amino acid composition and immune properties from troponin T from skeletal muscles. In the blood of healthy people, even after excessive physical exertion, the concentration of troponin T does not exceed 0.2-0.5 ng/ml, therefore, detection of its level above the specified limit indicates damage to the heart muscle.
Myoglobin is dissolved in cytosol, so it increases in the blood first. Then KK and KK-MB appear, but they disappear from the blood quite quickly (in the first 1-2 days). LDH and LDH 1 appear later and remain longer.
Dynamics of changes in myocardial infarction markers
Parameter |
Start of increase in activity, h |
Maximum increase in activity, h |
Return to normal, days |
Magnification factor, times |
KK |
2-4 |
24-36 |
3-6 |
3-30 |
KK-MB |
2-4 |
12-18 |
2-3 |
Up to 8 |
LDG |
8-10 |
48-72 |
6-15 |
Up to 8 |
LDG 1 |
8-10 |
30-72 |
7-20 |
Up to 8 |
Myoglobin |
0.5-2 |
6-12 |
0.5-1 |
Up to 20 |
Troponin T |
3.5-10 |
12-18 (and 3-5th day) |
7-20 |
Up to 400 |
The kinetics of troponin T in myocardial infarction differs from that of enzymes. On the first day, the increase in troponin T depends on the blood flow in the infarction zone. In myocardial infarction, troponin T increases in the blood already 3-4 hours after the onset of a pain attack, the peak of its concentration occurs on the 3-4th day, a "plateau" is observed for 5-7 days, then the level of troponin T gradually decreases, but remains elevated until the 10-20th day.
In uncomplicated myocardial infarction, the concentration of troponin T decreases by the 5th-6th day, and by the 7th day, elevated troponin T values are detected in 60% of patients.
The specificity of determining troponin T in the blood during myocardial infarction is 90-100%. In the first 2 hours from the onset of a pain attack, the sensitivity of determining troponin T is 33%, after 4 hours - 50%, after 10 hours - 100%, on the 7th day - 84%.