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What is Troponin-T test? 

The troponin-T test determines the amount of the protein troponin T in a person’s blood.

Troponins are found in skeletal and heart muscle of the body. There are three types of troponins: troponin I, C and T. Cardiac troponin I and C are subgroups of these troponins. Cardiac troponin T is expressed in the heart muscle fibres. Normally, troponin T is not found in the bloodstream. It appears in circulation when there is damage to heart muscles.

An elevation in troponin T level indicates that you are having a heart attack or have had a heart attack recently.

Following heart muscle damage, troponin T levels in the blood increase within three to 12 hours and get back to normal within 10 to 15 days. Higher amounts of troponin will be seen in the blood as the heart damage worsens.

Troponin T has a very high specificity for heart muscle injury; hence, it is very useful in the evaluation of a patient with chest pain. Doctors usually order this test along with other cardiac tests such as myoglobin, CK (creatine kinase) and CK-MB (creatine kinase-myocardial band) for detecting heart attack.

Troponins can also predict the probability of any forthcoming cardiac events.

  1. Why is a Troponin-T test performed?
  2. How do you prepare for a Troponin-T test?
  3. How is a Troponin-T test performed?
  4. Troponin-T test results and normal range

The troponin-T test is ordered in the emergency room when a patient shows the following symptoms of a heart attack:

Also, this test is used in the following cardiac clinical situations:

  • Unstable angina
  • Estimation of the severity of a heart attack
  • Detection of a heart attack around the time of a surgery
  • Evaluation of the severity of pulmonary embolism (blood clot in the lung)
  • Congestive heart failure

Troponin T is always preferred over troponin I for diagnosing heart attacks because of its higher specificity and sensitivity towards heart muscle injury.

Troponin T levels help in predicting the long-term risk of cardiac death in a patient with other complications such as end-stage renal disease.

After you have been tested once, this test may be repeated over the next 24 hours. A repeat test helps the doctor to check for any changes in the levels of troponin T over time.

No special preparations are required for a troponin T test. Intramuscular injections, vigorous exercising and medications do not interfere with the results of this test.

Your doctor will withdraw a blood sample from a vein in your arm. You may feel a slight pricking sensation when the needle is inserted - it will subside soon. If you have felt dizzy or faint during a blood test in the past or if you are scared of needles or the sight of blood, please inform your doctor or nurse so that they can help you feel more comfortable.

Normal results:

The normal value for cardiac troponin T is <0.2 ng/mL (nanograms per millilitre).

This value may differ slightly from one laboratory to another. Also, the presence of even a small amount of troponin T in the blood often means some damage to the heart. Please speak to your doctor for an accurate interpretation of your results. 

If your troponin T levels are normal for 12 hours after chest pain, it is unlikely that you have a heart attack. In such a case, your symptoms may be attributed to another condition.

Abnormal results:

Increased troponin T levels (> 0.2 ng/mL) may also be seen in the following conditions:

Significantly increased troponin T levels usually indicate that a heart attack has occurred. Troponin T levels remain high for one to two weeks after a heart attack.

Dialysis patients may show false-positive results.

Disclaimer: All results must be clinically correlated with the patient’s complaints to make a complete and accurate diagnosis. The above information is provided from a purely educational point of view and is in no way a substitute for medical advice by a qualified doctor.

References

  1. Wilson D. McGraw-Hill’s Manual of Laboratory & Diagnostic Tests, 2008. The Mc Graw Hills companies Inc., Pp:571-572.
  2. UW Health: American Family Children's Hospital [Internet]. Madison (WI): University of Wisconsin Hospitals and Clinics Authority; Heart Attack and Unstable Angina
  3. Hinkle J, Cheever K. Brunner & Suddarth's Handbook of Laboratory and Diagnostic Tests. 2nd Ed, Kindle. Philadelphia: Wolters Kluwer Health, Lippincott Williams & Wilkins; c2014. Troponin; p. 492-3.
  4. University of Rochester Medical Center [Internet]. Rochester (NY): University of Rochester Medical Center; Troponin
  5. Maynard S J, Menown I B A, Adgey A A J. Troponin T or troponin I as cardiac markers in ischaemic heart disease. Heart 2000;83:371-373.
  6. UF Health [Internet]. University of Florida Health. Florida. US; Troponin test
  7. National Heart, Lung, and Blood Institute [Internet]. Bethesda (MD): U.S. Department of Health and Human Services; Blood Tests
  8. National Heart, Lung, and Blood Institute [Internet]. Bethesda (MD): U.S. Department of Health and Human Services; Heart Attack
  9. Anderson JL. ST segment elevation acute myocardial infarction and complications of myocardial infarction. In: Goldman L, Schafer AI, eds. Goldman-Cecil Medicine. 25th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 73.
  10. Levine GN, et al. 2015 ACC/AHA/SCAI Focused Update on Primary Percutaneous Coronary Intervention for Patients With ST-Elevation Myocardial Infarction: An Update of the 2011 ACCF/AHA/SCAI Guideline for Percutaneous Coronary Intervention and the 2013 ACCF/AHA Guideline for t. Circulation. 2016 Mar 15;133(11):1135-47. PMID: 26490017.
  11. Sabatine MS, Cannon CP. Approach to the patient with chest pain. In: Mann DL, Zipes DP, Libby P, Bonow RO, Braunwald E, eds. Braunwald's Heart Disease: A Textbook of Cardiovascular Medicine. 10th ed. Philadelphia, PA: Elsevier Saunders; 2015:chap 50.
  12. Tehrani DM, Seto AH. Third universal definition of myocardial infarction: update, caveats, differential diagnoses. Cleve Clin J Med. 2013 Dec;80(12):777-86. PMID: 24307162.
  13. Pagana K.D, Pagana T.J, Pagana T.N. Mosby’s Diagnostic and Laboratory Test Reference. 14th ed. Pg: 912.
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