Troponin (cardiac troponin T and I)

Troponin is a protein complex in muscle fibres made up of three parts: troponin C, I and T. Heart muscle cells have their own forms of troponin I and T, which differ from those of skeletal muscle – this is why cardiac troponin is regarded as a highly heart-specific value. It is measured in serum, in the test catalogue together with NT-proBNP and D-dimers; the blood sample is taken in a practice and sent by express delivery.

What troponin does in the body

Troponin helps to control every heartbeat. In relaxed muscle, together with the protein tropomyosin, it blocks the sites where the muscle filaments actin and myosin could grip each other. When an electrical impulse arrives, calcium flows into the cell and binds to troponin C. The complex then changes shape, frees the binding sites, and myosin can pull on actin – the muscle contracts. When calcium falls again, troponin closes the sites and the heart muscle relaxes. Healthy heart muscle cells release only very small amounts of troponin into the blood.

Low or undetectable troponin – what does it mean?

A low or undetectable troponin value is the normal case. Highly sensitive methods can also find small amounts in healthy people, coming from ongoing cell turnover. A low value speaks against increased damage to heart muscle cells at the time of the blood sample. It only ever applies to that point in time, because troponin rises over several hours after damage. Acute chest pain, tightness or sudden shortness of breath therefore always require immediate medical attention – a blood sample sent by post is not intended for this.

Raised troponin – what happens in the body?

A raised troponin value shows that heart muscle cells are damaged and releasing their contents into the blood. This happens in a heart attack, when a coronary artery is blocked and muscle tissue dies without oxygen, but also with inflammation of the heart muscle, for example after viral infections, with heart failure, with rhythm disturbances and a very fast pulse, or with a pulmonary embolism that strains the right ventricle. After very long, intense endurance exercise, troponin can rise temporarily. With reduced kidney function it is excreted more slowly and stays somewhat higher. After COVID-19, studies have observed signs of heart involvement in some of those affected.

The interpretation is given in your report.