Understanding Troponin Levels and Test Results

Medically Reviewed By Darragh O'Carroll, MD
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Troponin is a protein in heart muscle that regulates heart muscle contractions. A troponin test is a laboratory test that measures troponin levels in blood. High troponin levels may indicate heart damage. Doctors use a troponin test to quickly assess if the cause of chest pain is heart-related. Because there are many reasons for chest pain, knowing if the pain is heart-related can be lifesaving. Measuring troponin levels gives doctors this information.

A troponin test measures three components of the troponin complex. There also are two types of troponin tests: regular and high-sensitivity. All this can make interpreting troponin levels challenging.

A high-sensitivity cardiac troponin T (hscTnT) test has a general cutoff to rule out heart damage. The cutoff level is 10 nanograms per liter (ng/L) or lower for females (assigned at birth). The level is 15 ng/L or lower for males (assigned at birth).

Other names for a troponin test include cardiac troponin and cardiac-specific troponin. A troponin level test involves a blood draw from a vein.

This article explains troponin levels, why doctors order a troponin test, and what the results mean.

Sex and gender terms

Sex and gender exist on spectrums. This article uses the terms “male” and “female” to refer to a person’s sex assigned at birth.

What is troponin?

Lab technician and blood test capsules
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Troponin is a protein inside heart muscle cells. It plays a role in heart muscle contraction. 

Normally, there is no troponin circulating in the blood. However, when heart muscle cells sustain damage, they release troponin. Doctors can measure troponin in the blood. The more damage to the cells, the higher the troponin level will go.

There are three subunits that make up the troponin complex in heart muscle cells:

  • cardiac troponin C (cTnC): This subunit binds to calcium, which initiates heart muscle contraction. 
  • cardiac troponin I (cTnI): This subunit relaxes the heart muscle.
  • cardiac troponin T (cTnT): This subunit facilitates heart muscle contraction.

A troponin test checks the levels of cTnI and cTnT. These two subunits are nearly exclusive to heart muscle.

Why do you need a troponin level test?

The main reason for a troponin level test is to help doctors diagnose conditions that injure the heart muscle. Specifically, doctors primarily use troponin levels to determine if someone is having a heart attack

Symptoms of a potential heart attack include:

Seek immediate medical care (call 911) for any of these serious symptoms. 

What do troponin level test results mean?

An elevated level of troponin in the blood usually indicates the occurrence of a heart attack.

Normal troponin levels are undetectable. The standard for high troponin levels is anything above the 99th percentile of the upper reference limit. This means that the level is higher than 99% of levels in a healthy control population. Guidelines use this system because the actual numbers vary from test to test. 

A regular troponin test measures troponin in nanograms per milliliter (ng/mL). High-sensitivity tests measure troponin in nanograms per liter. In addition, there are several manufacturers of troponin tests, with varying measurements. These tests are not equivalent.

In general, the reference ranges for regular troponin tests are:

  • cTnI: 0.04 ng/mL or lower
  • cTnT: 0.01 ng/mL or lower

For high-sensitivity cTnT tests, doctors may use these general cutoffs to rule out heart damage:

  • females: 10 ng/L or lower
  • males: 15 ng/L or lower

Doctors often repeat the troponin test to gauge any change, either up or down, in the level.

What causes elevated troponin levels?

The main cause of an elevated troponin level is injury to the heart muscle, specifically a heart attack. However, there are other cardiac conditions that directly damage the heart or reduce blood flow to the heart. This can increase troponin levels. These conditions include:

Systemic conditions that can damage the heart and raise troponin levels include:

What does a low troponin level mean?

In healthy people, a troponin level is normally undetectable. An undetectable level is below the limit of detection for the test. For the high-sensitivity cTnT test, this level is generally below 6 ng/L. 

When levels are detectable but below the 99th percentile cutoff, doctors will repeat the test to look for a trend. Troponin levels usually rise over a period of 12 hours after a heart attack.

What happens during a troponin level test?

A troponin level test involves a blood draw, usually from a vein in your arm. You may already have a catheter in an arm vein as part of admission to the emergency room. Otherwise, a small needle can collect the sample.

The results typically come back quickly, in 1–2 hours. For people at low risk, an undetectable level is often enough to rule out a heart attack. 

Repeat testing is necessary for those at high risk or when levels are detectable but low. Doctors will generally repeat the test every few hours for the next 12–24 hours.

Other frequently asked questions

The following frequently asked questions have been reviewed by Darragh O’Carroll, M.D.

How quickly do you receive troponin level test results? 

Troponin level tests are part of emergency triage for people having chest pain or other symptoms of a heart attack. Doctors generally get the results back quickly, within an hour or two. They will share the results with you and advise you about the next steps in ruling in or ruling out a heart attack.

What does a high troponin level indicate?

High troponin levels indicate that the heart muscle has sustained some type of injury. The level cannot tell you what specifically caused it. To diagnose the cause, doctors will evaluate your entire clinical picture. This includes your symptoms, medical history, electrocardiogram results, and imaging exams.

Is high blood pressure related to higher troponin levels?

High blood pressure is one of the cardiac disorders that can lead to an elevated troponin level. Research suggests that the high-sensitivity test is one way to gauge the risk of future cardiovascular events. In people with high blood pressure, troponin level may help guide decisions about how aggressive treatment should be.

Summary

Troponin is a protein that is almost exclusive to heart muscle cells. In healthy people, troponin is virtually absent from the blood. Its presence in the blood indicates that some type of damage has occurred to the heart.

Doctors can use this marker to quickly identify people who have likely experienced a cardiac event. In most cases, this is a heart attack. The ease of running this test means doctors can start lifesaving treatment without delay.

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Medical Reviewer: Darragh O'Carroll, MD
Last Review Date: 2022 Aug 26
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THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. Never ignore professional medical advice in seeking treatment because of something you have read on the site. If you think you may have a medical emergency, immediately call your doctor or dial 911.
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