Troponin Test - Procedure, Indications, and Complications

What Is Troponin?

Troponin is a contractile muscle protein in the human cardiac and skeletal muscle systems.

It is not found in the blood commonly, but after myocardial injury or damage to the cardiac muscles, the troponin is released into the bloodstream at a high value.

Troponin belongs to the family of calcium (Ca 2+) regulatory proteins. The presence of troponin in cardiac muscle and skeletal muscle forms a complex with calcium; therefore, it is responsible for the contraction of the muscles.

What Are the Types of Troponin?

Troponin is available in three types; one type is responsible for binding with calcium, and the other two are responsible for binding with actin and tropomyosin. They are called troponin complexes, and they are as follows -

1. Troponin C - It is mainly responsible for binding with calcium, which initiates the contraction in the cardiac and skeletal muscles.

2. Troponin I - It is present in cardiac and skeletal muscle and binds to actin.

3. Troponin T - It is responsible for binding with tropomyosin.

What Is the Cardiac Specificity of the Troponin?

Troponin protein is present in both the cardiac and skeletal muscles. There are different types of troponin, like Troponin C, I, and T, which are specific to a particular type of muscle. Troponin C is present in both the cardiac and skeletal muscles; Troponin I and Troponin T are present in cardiac muscle and are specific to the cardiac muscle, which is different from the skeletal muscle. Therefore, they are called cTnI (cardiac troponin I) and cTnT cardiac troponin T.

These are specific cardiac biomarkers, and when released into the blood, they indicate possible cardiac damage. Other biomarkers are also elevated in cardiac muscle damage, such as CK (creatine kinase) and myoglobin (a type of protein in striated muscles).

What Is the Troponin Test?

The troponin test is an investigation for the indication of cardiac damage. It is preferred to check the elevated range of troponin in the blood. The elevation of troponin level may help diagnose cardiac arrest, less blood supply causing ischemia, or any injury to the cardiac muscles.

What Is the Role of Troponin?

The cardiac muscle has myosin fibers and actin filaments with a double helix structure with tropomyosin.

• The actin filaments have troponin T, which is attached to troponin I and troponin C, and these are responsible for binding with the calcium molecule. This is the combination of troponin complexes present in the cardiac muscle.

• When the calcium enters the cardiac cells, it binds with the troponin complex and produces a conformational change with tropomyosin resulting in exposure of myosin binding sites.

• To the myosin-binding sites, the myosin filaments can be attached, which produces some contraction in the cardiac muscles.

How Does Troponin Release in the Blood?

• In the standard structure of both the filament, actin, and myosin, cardiac damage results in decreased oxygen supply, causing cell death, ischemia, and further cardiac destruction.

• Due to cardiac damage, the loss of muscles leads to the availability of troponin in the free form within the cytoplasm, and it can be transported into the blood along with the troponin complex.

• This elevates the troponin level in the blood and helps indicate cardiac damage.

• Estimating the troponin level in the blood helps to assess cardiac damage.

What Is the Normal Range of Troponin?

Troponin is a biomarker for cardiac damage, so it is present at very low levels; the blood in around 0.02 nanogram per milliliter to 0.01 nanogram per milliliter is normal; if there is no damage.

When Is the Troponin Level Elevated in the Blood?

Troponin level gets elevated in blood when there is cardiac damage. It can get elevated in the following disorders:

1. Atrial fibrillation (irregular or rapid heart rate).

2. Myocardial infarction (heart attack).

3. Heart failure.

4. Breathing issues.

5. Renal disorders (like nephrotic syndrome, kidney failures, and other disorders related to the renal system).

6. Pulmonary embolism (blockage in pulmonary arteries).

What Is the Procedure of the Troponin Test?

The procedure of the troponin test is very simple; it is performed by a phlebotomist or other trained professional. The sample is taken from the arm through the brachial artery using a small needle. Then, the sample is collected in the test tube.

What Are the Complications of the Troponin Test?

The procedure is simple, but it can lead to some complications while the sample is collected. A small needle is used to inject into the vein, and it may develop small dark-colored bruises oozing out of the blood. These complications can be cured with time and by applying pressure on the prick for clot formation.

When Is the Troponin Test Indicated?

Indication for the troponin test includes:

1. Pain and discomfort in the chest.

2. Shortness of breath.

3. Fatigue.

4. Pain in neck, shoulder, and jaws.

5. Sweating.

6. Palpation (increased heart rate).

7. Silent heart attack.

What Do the Troponin Test Results Mean?

The results of the troponin test indicate the value of cardiac damage.

• If the test results show the value of troponin between 0.04 nanogram per milliliter to 0.39 nanogram per milliliter in the blood, this indicates a problem in the heart.

• If the test results show a level of troponin above then the 0.04 nanogram per milliliter, it indicates cardiac arrest.

Some other investigations are used for examination, such as the electrocardiogram (ECG) and blood oxygen level.

What Should Be Expected From the Test Results?

A troponin test is done to know the risk of heart attack; it could be performed in an emergency.

The test may show some different ranges of the troponin if the test gets delayed; the elevated troponin level can be seen in the blood till five to seven days after the heart attack. Therefore, repetition of the troponin test is required to understand the degree of cardiac damage. There can be some interference in the ranges of the troponin because of the intake of other supplements like vitamin B7. After getting the test results, it can lead to further required investigations and planning of the treatment accordingly.

Conclusion -

The troponin test is indicated for cardiac problems. It can be used in emergency cases like a heart attack. Detecting a slight elevation of troponin in the blood can help to prevent major cardiac problems. The procedure for the test is simple and cost-effective for an individual.