A positive troponin result is defined by what criterion?

• A. Maximum value above the 90th percentile
• B. Maximum value above the 95th percentile
• C. Maximum value above the 99th percentile
• D. Maximum value above the 100th percentile

Answer: (C)

A positive troponin result is defined by any value that exceeds the 99th percentile of a healthy reference population. This upper reference limit is chosen to reliably indicate myocardial injury while avoiding too many false positives that would occur if the threshold were higher (like the 90th or 95th percentile). The 100th percentile isn’t a usable cutoff, since there is no value above the maximum of the reference distribution. In practice, a troponin above this 99th percentile is considered elevated, and clinicians look for a rise and/or fall with serial testing to support an acute injury rather than a chronic elevation.