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Cardiac Markers

Troponin I

Normal range < 0.04 (assay-dependent) ng/mL (< 0.04 µg/L SI). Specimen: Serum or plasma.

Also known as: cTnI, cardiac troponin I.

< 0.04 (assay-dependent) ng/mLCritical: read below

Reference range

This result is reported qualitatively or as a one-sided threshold rather than a two-sided numeric band.

SpecimenSerum or plasma
Conventional range< 0.04 (assay-dependent) ng/mL
SI range< 0.04 µg/L
Conversion factor×1 (conventional → SI)
Critical valueAny elevation above the 99th percentile signals myocardial injury
PanelCardiac Markers

Convert any Troponin I result between units on the unit converter.

What is the normal range for Troponin I?

The standard teaching reference range for Troponin I is < 0.04 (assay-dependent) ng/mL in conventional units, or < 0.04 µg/L in SI units. This value is measured in serum or plasma.

A commonly taught critical (panic) value is Any elevation above the 99th percentile signals myocardial injury. Critical results are reported to the provider immediately under your facility's policy.

Source: Adult reference values compiled from Pagana & Pagana, Mosby's Diagnostic and Laboratory Test Reference, and Fischbach & Dunning, A Manual of Laboratory and Diagnostic Tests. Reference ranges vary by laboratory, method, age, sex, and population — always use the range printed on the actual result.

Above the range

Common causes of a high Troponin I

  • Acute myocardial infarction
  • Myocarditis
  • Heart failure or PE
  • Renal failure (chronic elevation)

At the bedside

Nursing considerations

  • The preferred marker for MI — highly cardiac-specific.
  • Draw serial troponins (e.g. 0 and 3–6 h) to detect a rise-and-fall pattern.
  • Thresholds differ by assay, especially high-sensitivity troponin.

Study aid

Your notes on Troponin I

Same panel

More Cardiac Markers tests

B-type Natriuretic Peptide (BNP)< 100 (heart failure unlikely) pg/mLCK-MB< 5 (or < 5% of total CK) ng/mLCreatine Kinase (CK)30–200 U/LMyoglobin25–72 ng/mLNT-proBNP< 125 (age < 75); < 450 if older pg/mLTroponin T< 0.01 (assay-dependent) ng/mL