Troponins are proteins found in the cardiac muscles. When the heart is damaged, it releases troponin into the bloodstream.
Doctors measure your cardiac troponin levels to help detect whether you’re experiencing a heart attack. A troponin test can also help doctors find the best treatment sooner.
Previously, doctors used other blood tests (like the CPK isoenzymes test) to detect a heart attack. But they aren’t always the optimal test because they aren’t sensitive enough to detect every attack. Smaller heart attacks leave no trace on these blood tests. The other tests also measure substances that aren’t specific enough to the heart muscle.
Troponin is more sensitive. Measuring cardiac troponin levels in the blood allows doctors to diagnose a heart attack or other heart-related conditions more effectively and provide immediate treatment.
Troponin levels are measured with a standard blood test. A healthcare professional will take a sample of your blood from a vein in your arm. You can expect mild pain and maybe light bruising.
After taking the blood sample, the healthcare professional will assess your troponin levels to diagnose a heart attack. They’ll also look for any changes on an electrocardiogram (ECG or EKG), an electrical tracing of your heart.
These tests may be repeated several times over a 24-hour period to look for changes.
With a conventional troponin test, it can take hours before increased levels of troponin are detectable. Using this test too soon can produce a false negative.
A high-sensitivity troponin test is also available. This test can detect elevated troponin levels and produce positive test results in as little as 9 minutes.
If your troponin levels are low or normal after experiencing chest pain, you probably have not experienced a heart attack. If your levels are high, the likelihood of heart damage or heart attack is high.
In addition to measuring your troponin levels and monitoring your ECG or EKG, the healthcare professional may want to perform other tests to examine your health, including:
Troponin proteins help regulate muscle contraction. They’re split into three subunits:
- troponin C (TnC), which binds to calcium, initiates muscle contraction, and helps move TnI
- troponin I (TnI), which works with TnC to pull the muscle fibers
- troponin T (TnT), which anchors the troponin proteins to a separate protein called tropomyosin
Troponin tests measure levels of either TnI or TnT.
Your doctor will recommend this test if you’re experiencing chest pain or related heart attack symptoms, including:
Troponin levels are measured in nanograms per milliliter (ng/mL). High-sensitivity tests measure troponin levels in nanograms per liter (ng/L).
Normal levels fall below the 99th percentile in the blood test. If troponin results are above this level, it may indicate heart damage or heart attack. Reference ranges for troponin levels will vary by test lab.
A 2017 study suggests that women may have lower cardiac troponin levels than men. As a result, women can experience heart damage from a heart attack at levels below the current “normal” cutoff for some labs. In other labs, what’s considered normal may differ for men and women.
TnI levels are typically considered elevated if they’re
If your troponin levels are low or normal
In healthy people, troponin levels are within the normal range. If you’ve experienced chest pain, but troponin levels are still low or normal 12 hours after the chest pain started, the possibility of a heart attack is unlikely.
If your troponin levels are high
High levels of troponin are an immediate red flag. The higher the troponin levels, the more troponin — specifically TnI and TnT — that’s been released into the bloodstream and the higher the likelihood of heart damage. Troponin levels can become elevated within 3 to 6 hours after the heart’s been damaged and can remain high for 10 to 14 days.
Though a rise in troponin levels is often an indication of a heart attack, there are a number of other reasons why your troponin levels could be elevated.
Troponin levels can be acutely elevated or chronically elevated. If you’re experiencing symptoms in addition to a change in troponin levels, a healthcare professional will use your symptoms to help inform their diagnosis.
Other heart conditions that can contribute to high troponin levels include:
- myocarditis, which is inflammation of the heart muscle
- pericarditis, which is inflammation of the sac of the heart
- endocarditis, which is inflammation of the inner layer of the heart
- cardiomyopathy, which is a weakened heart
- heart failure
- stable angina, which is a type of chest pain caused by poor blood flow to the heart
Other possible causes of high troponin levels include:
- intense exercise
- medications, like metoprolol (Toprol XL, Lopressor)
- kidney disease
- pulmonary embolism, which is a blood clot in your lungs
- hypothyroidism, which is an underactive thyroid
- intestinal bleeding
- an extensive infection, like sepsis
Did you know?
High-sensitivity troponin tests can detect elevated troponin levels in people without symptoms of cardiovascular disease, according to a
2019 study. This means the test results can be used to help predict whether you’re at increased risk for a future cardiac event, like a heart attack or stroke.
Troponin is a protein released into your blood after you experience a heart attack. High troponin levels can be indicators of other heart conditions or illnesses, too.
If you begin to experience chest pain or suspect you’re having a heart attack, call 911 or your local emergency services. Heart attacks and other heart conditions can be fatal.
All chest pain should be evaluated in an emergency room. Self-diagnosis is never recommended.