Cardiac troponins: are there any differences between T and I?

Area of Science:

• Clinical Biochemistry
• Cardiology
• Laboratory Medicine

Background:

• International guidelines recommend high-sensitivity cardiac troponin (hs-cTn) assays for detecting myocardial injury and diagnosing acute coronary syndromes.
• Myocardial injury, defined by hs-cTn levels above the 99th percentile, is essential for diagnosing myocardial infarction but is also a distinct clinical entity.
• Elevated hs-cTnT levels are observed in neuromuscular diseases, often without corresponding hs-cTnI elevations.

Purpose of the Study:

• To review the biochemical, pathophysiological, and analytical factors contributing to discrepancies between hs-cTnI and hs-cTnT measurements.
• To elucidate the reasons behind differing hs-cTn results in patients with and without cardiac disease, and in those with neuromuscular conditions.

Main Methods:

• Literature review of biochemical, pathophysiological, and analytical mechanisms affecting hs-cTnI and hs-cTnT assays.
• Analysis of existing data on troponin discrepancies in various patient populations, including those with neuromuscular diseases and cardiac conditions.

Main Results:

• Discrepancies between hs-cTnI and hs-cTnT results are occasionally observed in individuals without apparent cardiac disease.
• Elevated hs-cTnT, but not hs-cTnI, is frequently noted in patients with congenital or chronic neuromuscular diseases.
• Variations in hs-cTn results can occur in patients with established cardiac diseases.

Conclusions:

• Understanding the mechanisms behind hs-cTnI and hs-cTnT discrepancies is critical for accurate myocardial injury assessment and diagnosis.
• The distinct behavior of cTnI and cTnT in certain conditions, like neuromuscular diseases, highlights the importance of considering assay-specific characteristics.