Troponin I, High Sensitivity Unit Converter

High-sensitivity troponin I (hs-cTnI) is a blood test that measures extremely small amounts of cardiac troponin I, a protein found almost exclusively in heart muscle cells.

Troponin I is part of a three-protein complex (troponin I, T, and C) that regulates heart muscle contraction. When heart muscle cells are injured or damaged, troponin I leaks into the bloodstream, where it can be detected.

The "high-sensitivity" designation means the assay can detect troponin I at concentrations far lower than older tests, allowing earlier detection of heart injury. A small baseline amount of troponin circulates in healthy individuals due to normal heart cell turnover.

Cardiac troponin I is produced exclusively in heart muscle cells (cardiomyocytes), where it is part of the contractile machinery that controls heartbeat. About 3.5% of troponin I in heart cells exists freely in the cytoplasm, while the rest is bound to the contractile filaments.