H S Troponin I, Serum

Various clinical studies suggest that troponin levels are elevated after an episode of Myocardial Infarction or Ischemic Damage. Measuring the levels help form or exclude a diagnosis of an MI event.

Clinical studies have reported that cTnI is released into the blood stream within hours of the onset of symptoms of MI or ischemic damage. It can be detected at 3 to 6 hours following onset of chest pain with peak concentrations at 12 to 16 hours and remains elevated for 5 to 9 days, providing more opportunity for detecting MI or excluding the diagnosis.

This test is typically done in a hospital setting.

Serial sampling is recommended to detect the temporal rise and fall of troponin levels characteristic of MI. An elevated troponin alone is not sufficient to make the diagnosis of MI. Other markers, such as CK-MB and myoglobin, can be used in conjunction with cTnI results in aiding the diagnosis of MI.

Definition of Acute Myocardial Infarction

The World Health Organization (WHO) criteria for defining Acute Myocardial Infarction (AMI) are the presence of two of the following three elements:

• Continual chest pain for greater than 20 minutes
• ECG changes with ST-segment elevation

Elevated cardiac markers.

Requirement: No special preparation required.

Reference values for Troponin I test  

Male      -    <34.20 pg/ml

Female   -    <15.6 pg/ml

Interpretation of Troponin I values

A positive troponin result is not always indicative of MI. Other conditions resulting in myocardial cell damage can contribute to elevated cardiac troponin I levels. These conditions include, but are not limited to myocarditis, cardiac surgery, angina, unstable angina, congestive heart failure and non-cardiac related causes, such as, renal failure and pulmonary embolism.

Risk Stratification Analysis of Acute Coronary Syndrome -

Because of its cardiac specificity and sensitivity, cTnI has been used as reliable marker in evaluating patients with unstable angina, a conditions implying increased risk of MI and sudden death. Unstable angina patients with minimal values of cTnI are predicted to have a higher risk of short-term mortality. As the cTnI value progressively increases, the risk of mortality increases, presumably because the amount of myocardial damage also increases.