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Hematologist, oncohematologist

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Troponin T in the blood

Alexey Portnov, medical expert
Last reviewed: 20.11.2021

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The reference values (norm) of 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 link to 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 may be a precursor for the synthesis of the troponin complex, 7% in the cytosol (which explains the biphasic peak of increased troponin concentration in myocardial infarction). Troponin T from the cardiac muscle by amino acid composition and immune properties is different from troponin T of 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, so detecting its level above this limit indicates damage to the heart muscle.

Myoglobin is dissolved in the cytosol, so it rises in the blood first. Further there are KK and KK-MB, but they quickly disappear from the blood (in the first 1-2 days). LDG and LDG ₁ appear later and last longer.

The dynamics of changes in markers of myocardial infarction

Parameter	Start increasing activity, h	Maximum activity increase, h	Return to normal, day	Multiplicity of magnification, times
QC	2-4	24-36	3-6	3-30
KK-MB	2-4	12-18	2-3	Up to 8
LDH	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 3-5 day)	7-20	Up to 400

The kinetics of troponin T in myocardial infarction is different from that of enzymes. On the first day, the increase in troponin T depends on the blood flow in the infarction zone. With myocardial infarction, troponin T rises in the blood within 3-4 hours after the onset of the pain attack, the peak of its concentration falls on the 3rd-4th day, the "plateau" is observed for 5-7 days, then the level of troponin T gradually decreases, however remains elevated to 10-20 days.

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.

Specificity of determination of troponin T in the blood with myocardial infarction is 90-100%. In the first 2 hours after the onset of a painful attack, the sensitivity of the determination of troponin T is 33%, after 4 hours - 50%, after 10 hours - 100%, on the 7th day - 84%.

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