Reading a troponin without panicking

High-sensitivity troponin assays were supposed to make life easier. Instead they made everyone slightly insane, because now you can detect troponin in people who are completely fine. Here's how to keep your head.

Troponin answers "is there myocardial injury," not "is this an MI"

Those are different questions. Injury is a finding. MI is a diagnosis that requires injury plus a clinical story of ischemia. A bump in a septic, tachycardic, renally-impaired patient is often real injury — and often not an MI.

The verb that matters is "delta"

A single value is a dot. The change between values is the signal.

• A high value that's flat across serial draws points away from acute infarction.
• A modest value that's rising fast is louder than a higher value that's stable.
• The assay's reference change matters more than the headline number.

Don't ask "is the troponin positive?" Ask "where did it start, and which way is it moving?"

Tie it back to the cloud

Pre-test probability sets how much a troponin should move your needle. The same number means very different things in a 34-year-old with reproducible chest-wall pain and a 72-year-old diabetic with an hour of pressure. The lab doesn't know which patient it came from. You do. That's the job the assay can't do for you.