A 58-year-old man is admitted with acute chest pain. Serial troponin-I levels are measured at 0, 6, and 12 hours. The attending physician notes that high-sensitivity troponin-I (hs-TnI) is preferred over conventional troponin because it allows earlier rule-out. Which property of hs-TnI assay primarily enables a 0/3-hour rule-out algorithm?
- A Detects skeletal muscle-specific isoform exclusively
- B Binds free troponin released only during irreversible injury
- C Lower coefficient of variation at the 99th percentile URL ✓
- D Measures total troponin including complexed cardiac forms only
Correct answer: C. Lower coefficient of variation at the 99th percentile URL
Explanation
High-sensitivity troponin assays have a coefficient of variation (CV) ≤10% at the 99th percentile URL, meaning they can accurately detect very small concentrations that standard assays misclassify as undetectable. This precision at low concentrations allows statistically meaningful delta-change calculations within 3 hours of presentation, enabling early rule-out (baseline below URL + small delta = low-risk). Skeletal muscle isoform distinction and complex-binding properties are not unique to hs-TnI.
Reference: Harper's Illustrated Biochemistry, 32nd ed.
High-yield for: NEET PGINI-CETNExTFMGEUSMLEPLABMRCP
Written and medically reviewed by the StethoPrep medical team.