Troponin Test

Troponin test is a significant diagnostic marker in the identification of cardiac impairments such as infarctions. It is recommended in almost all medical facilities especially as an advanced cardiac life support diagnostic test. The efficiency of this test is that it helps in identifying small degrees of damage to heart muscle cells. The most common cause of cardiac injury is myocardial ischemia.

For this test to be reliable, it must be administered within 6 to 12 hours of chest pain or any other typical symptom of heart disease. With a Troponin test, patients displaying ECG variations or palpitations can rule out myocardial infarction. Based upon the analysis of the vital signs and Troponin test, the physician recommends a specific type of treatment or procedure associated with the condition.

Troponins are muscle proteins found in striated muscles and their role in identifying cardiac conditions and embolisms associated with brain and lungs are remarkable. These indicators or markers are precise in their identification pattern, which paves the way to rule out complex conditions associated with the heart, lungs and the brain.

There are 2 types of myofilament, a thick filament of myosin and a thin filament of 3 different proteins:

• Actin
  
• Tropomyosin
  
• Troponin
  

Troponin is itself a complex of 3 proteins:
Troponin T
Troponin I
Troponin C.

Troponin T is associated with tropomyosin binding sites, Troponin I inhibits the contraction of actin and myosin - actomyosin ATPase and Troponin C is associated with calcium channel binding. In the cytosol, Troponin T is found in free as well as protein bound forms. The unbound free pool of troponin T is released in the initial phase of myocardial damage while the bound Troponin T is released at a later stage, in tune with the degradation of myofibrils and irreversible myocardial damage.

Acute Myocardial Infarction (AMI) or Myocardial Ischemia is the primary cause of cardiac injury. Troponins - the marker proteins have a unique diagnostic window in that the timeline during which the marker rises, peaks and returns to normal is of significance. Troponin levels rise within 2 - 4 hours after the onset of myocardial necrosis and stays high for up to 14 days. This long window of elevated levels allows detection of Myocardial Infarction that occurred several days ago. Troponin levels enable us to predict the extent of heart muscle damage. Troponin levels in a healthy individual will be negligible (less than 0.5 ng/mL). The greater the amount of troponin in the blood, greater is the damage to the heart. Troponin I value less than 10 microgram per liter is considered as normal whereas troponin T value should be less than 0.1 microgram per liter.

Troponin levels greater than 2.0 ng/mL indicate significant myocardial damage and is at an elevated level of risk for further serious heart conditions. Levels between 0.5 and 2.0 ng/mL indicate a possible diagnosis of unstable angina, other heart ailments or chronic kidney failure. In some cases the finding of unstable angina and an elevated troponin T may well be a unique response to treatment techniques involving anti platelet agents and heparin.

Each of these muscle proteins has specific origin of action and hence they are closely associated with the cardiovascular system. Troponin test is ordered mostly as an emergency care measure in order to stop an adverse effect caused due to angina and Congestive heart failure (CHF).

There are two types of tests for troponins T and I:

1. Traditional quantitative test: Shows an actual measurement of troponin. Usually this test takes about 45 -90 minutes and is useful to distinguish between Myocardial Infarction and unstable Angina.
2. Qualitative test: Shows the result Positive or Negative. This test takes about 15 minutes and is useful in emergency rooms where critical decisions have to be taken based on the presence of Troponin level.
A 'negative' troponin test means that the protein was not detected in the blood. A positive indicates the need for further evaluation.