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Troponin and tumor markers

15 min

Skills you'll build2 skills
  • Tell myocardial injury from infarction by troponin level, rise or fall, and ischemia
  • Use a tumor marker only to monitor a known cancer or screen a targeted group

Try first

Try first

One high-sensitivity troponin I result is above the assay's 99th-percentile upper reference limit. No other troponin has been measured yet. What does this single value establish?

Right. Keep going to follow the reasoning.

Keep going to see the reasoning.

Keep going to see the reasoning.

Keep going to see the reasoning.

Get the idea

Use the explanation to check your first decision.

Myocardial injury and infarction

The Fourth Universal Definition of Myocardial Infarction interprets troponin in three steps:1

  1. Injury. At least one value is above the 99th-percentile upper reference limit.
  2. Acute injury. Serial values rise or fall.
  3. Infarction. Acute injury comes with evidence of ischemia, such as ischemic symptoms, new ischemic ECG changes or imaging findings.

Many conditions injure heart muscle without a clot in a coronary artery. They include heart failure, myocarditis, cardiotoxic chemotherapy and chest trauma.1 Chronic kidney disease slows troponin clearance and often keeps values stably above the 99th percentile. A stable elevation with no rise or fall is chronic injury.2

Serial troponin on one assay

A high-sensitivity assay has a coefficient of variation of 10% or less at the 99th percentile and measures troponin in at least half of healthy people. Its 99th percentiles are set separately for men and women. They apply only to that assay.3 A nondiagnostic first result is repeated at the assay's set interval, often 1 to 2 hours.3,4 Troponin I and troponin T results from different assays are not interchangeable, so a series stays on one assay and one platform.2

Uses and limits of tumor markers

No tumor marker is at once specific to cancer, absent in healthy people and reliably detectable. Benign conditions raise many of them.2,5 Markers work poorly for screening people without symptoms, and one increased result does not show cancer. Their supported uses are monitoring treatment of a known cancer, finding recurrence, screening defined high-risk groups and supporting imaging and biopsy findings.2,5

Assays from different manufacturers often disagree for the same marker, so a patient's trend is followed on one assay.2

Follow the bench demonstration

Sources for this step
References
  1. Thygesen K, Alpert JS, Jaffe AS, et al. Fourth universal definition of myocardial infarction (2018). Circulation. 2018;138(20):e618-e651. doi:10.1161/CIR.0000000000000617
  2. Bishop ML, Fody EP, Van Siclen C, Mistler JM, Moy M. Clinical Chemistry: Principles, Techniques, and Correlations. 9th ed. Jones & Bartlett Learning; 2023.
  3. Wu AHB, Christenson RH, Greene DN, et al. Clinical laboratory practice recommendations for the use of cardiac troponin in acute coronary syndrome: expert opinion from the Academy of the American Association for Clinical Chemistry and the Task Force on Clinical Applications of Cardiac Bio-Markers of the International Federation of Clinical Chemistry and Laboratory Medicine. Clin Chem. 2018;64(4):645-655. doi:10.1373/clinchem.2017.277186
  4. Rao SV, O'Donoghue ML, Ruel M, et al. 2025 ACC/AHA/ACEP/NAEMSP/SCAI guideline for the management of patients with acute coronary syndromes: a report of the American College of Cardiology/American Heart Association Joint Committee on Clinical Practice Guidelines. Circulation. 2025;151(13):e771-e862. doi:10.1161/CIR.0000000000001309
  5. National Cancer Institute. Tumor markers. Reviewed December 7, 2023. Accessed September 27, 2026. https://www.cancer.gov/about-cancer/diagnosis-staging/diagnosis/tumor-markers-fact-sheet

Watch one

Read each decision and its explanation.

A 63-year-old woman comes to the emergency department with chest pressure. High-sensitivity troponin I is measured on arrival and 2 hours later on the same Meniscus CX-800 assay. In this example, the assay's 99th percentile for women is 16 ng/L, and the laboratory's change limit at 2 hours is 10 ng/L.

How does the laboratory interpret this series?

TestResultPreviousReference intervalFlag
hs-troponin I, 2 h96 ng/L Delta2 hours ago: 38 ng/L38 ng/L2 hours ago<16 ng/L<16Delta

Specimen: H 6, L 9, I 1. Lithium heparin plasma, both draws

  1. Check the series: both draws ran on the same assay, and neither specimen is hemolyzed.

    A rise or fall can be interpreted only when every value comes from the same assay and an acceptable specimen.

  2. Compare with the female 99th percentile of 16 ng/L. Both values are above it, so injury is present.

    The 99th percentile is sex-specific and applies to this assay.

  3. Measure the change: 96 − 38 = 58 ng/L, far beyond the 10 ng/L limit.

    A change larger than the assay's change limit shows the injury is acute.

  4. Report both values with the sex-specific limit. The troponin series shows acute injury, and infarction depends on evidence of ischemia.

    Infarction needs ischemia, which the care team judges from symptoms, the ECG and imaging.

The series shows acute myocardial injury. Both values are above the 16 ng/L limit, with a rise of 58 ng/L in 2 hours.

Practice this skill

Your turn

Problem 1 of 3 · Hints available

Serial cardiac troponin results rise and fall, with at least one value above the assay's 99th-percentile upper reference limit. What additional evidence does the definition of infarction require?

Incorrect. CK-MB is a historical marker that skeletal muscle disease and extreme exercise can also raise. It adds no evidence of ischemia.

Incorrect. More serial values describe the acute rise or fall. The definition still requires ischemic symptoms or electrocardiographic, imaging, or angiographic evidence.

Correct. The Fourth Universal Definition pairs acute myocardial injury with ischemic symptoms, new ischemic ECG changes, imaging, or other qualifying evidence before the term infarction applies.

Hint
  1. The rise and fall already show acute injury.
  2. Ask what separates infarction from other causes of acute injury.

Review Myocardial injury and infarction

Problem 2 of 3 · Hints available

Which use of a tumor-marker result is supported?

Incorrect. No available marker is tumor-specific, absent in health, and reliably detectable all at once, so markers are not intended for population-wide screening.

Correct. Serial tumor-marker results show how a known cancer responds to treatment.

Incorrect. Markers can be increased in health and in benign conditions, so one increased result is read with other findings in a diagnostic workup.

Hint
  1. Benign conditions and healthy people can have raised tumor markers.
  2. Ask which uses depend least on the marker being specific to cancer.

Review Limits of tumor markers

Problem 3 of 3 · On your own

A 71-year-old man with long-standing heart failure has high-sensitivity troponin I measured three times on one assay: 52 ng/L on arrival, 54 ng/L at 2 hours and 51 ng/L at 6 hours. The assay's 99th percentile for men is 34 ng/L, and its change limit is 10 ng/L. Which reading fits?

A change of 2 ng/L is well inside the 10 ng/L change limit. It is within the assay's expected variation.

Every value is above the 34 ng/L limit, so injury is present. A stable pattern indicates chronic injury.

Infarction needs acute injury, shown by a rise or fall, plus evidence of ischemia. These values are high and stable.

Called any elevated troponin an infarction

A value above the 99th-percentile upper reference limit defines myocardial injury, which kidney disease, heart failure, myocarditis, and chest trauma also cause. Infarction needs an acute rise or fall plus evidence of ischemia. Calling every elevation an infarction mislabels chronic and nonischemic injury.

All three values are above the 34 ng/L limit, and none changes by more than 3 ng/L. Stable elevation is chronic injury, which heart failure commonly causes.

Review Myocardial injury and infarction

Use it

Read the case evidence, then make each decision. The step is complete without it.

  • Henrik Coulter, 66, had colon cancer removed a year ago and has CEA drawn every 3 months.
  • His earlier CEA results came from an outside laboratory's assay.
  • Today's CEA is the first run on your Meniscus CX-800 assay, and it fails the delta check.
  • He has no new symptoms. QC is in control, and the specimen is clean.
TestResultPreviousReference intervalFlag
CEA4.6 ng/mL Delta3 months ago: 2.4 ng/mL2.4 ng/mL3 months ago<3.0 ng/mL<3.0Delta

Specimen: H 2, L 7, I 1. Serum, routine follow-up draw

Decision 1 of 2

What does the change from 2.4 to 4.6 ng/mL show?

One increased marker does not show cancer. Here the two values also come from different assays, which often disagree for CEA.

Read one increased tumor marker as confirmed cancer

No available marker is at once tumor-specific, absent in health, and reliably detectable, and many are raised by benign conditions. A single increased value does not establish cancer. Tumor markers are used to monitor a known cancer, to screen targeted groups, and to support imaging and biopsy findings.

CEA assays from different manufacturers often give different numbers for the same specimen. This is the first value on a new assay, so the size of any real change is unknown.

Monitoring a known colorectal cancer is the best-supported use of CEA. The trend needs values from one assay.

Review Limits of tumor markers

Decision 2 of 2

What do you do with the result?

The number is valid on this assay. The comment tells the reader why it cannot be compared directly with the older values, and later results on this assay build the new trend.

A repeat on the same assay gives the same answer. The question is the comparison between assays, and a repeat does not address it.

The specimen is sound. A new tube run on the same assay would show the same difference from the old laboratory's values.

The delta flag would be reported without explanation, and the rise could be interpreted as recurrence.

Review Limits of tumor markers

The change of assay explains the delta check failure. Both results may be correct on their own assays. CEA values from different manufacturers are not interchangeable, so the delta check compared results from two different assays, and a new baseline starts on this assay.

For reference

Sources checked