Troponin-T, and Troponin-I

What sample is needed for Troponin-T and Troponin-I?

1. It is done on the EDTA blood.
2. This test can also be performed on serum or plasma.
3. A serial sample may be needed.
4. The serum for troponin-T is stable for 24 hours at 2 to 8 °C.
   • Can store serum for three months at -20 °C.

What are the Indications for Troponin-T and Troponin-I?

1. This test is advised to rule out myocardial infarction (MI) in a patient with chest pain.
2. This is a specific indicator of cardiac damage or infarction.
3. This test is done for the early diagnosis of myocardial infarction.

How will you define troponins?

1. Troponins are contractile proteins found within muscle fibers that help regulate contractions.
2. What are the types of troponins?
   1. Troponin-T = Tropomyosin-binding component.
   2. Troponin-I =  Inhibitory component.
   3. Troponin-C = Calcium-binding component.
3. During muscle necrosis, Troponin-T and Troponin-I are released into the blood circulation.
4. Troponin-T and Troponin-I levels in the blood increase, indicating muscle necrosis.
5. Troponins are not raised in angina.

How will you discuss the pathophysiology of Troponin-T and Troponin-I?

1. Troponins are proteins present in the skeletal and cardiac muscles.
2. Troponins have a complex of three subunits:
   1. It will regulate the interaction of actin and myosin.
   2. These reactions of actin and myosin regulate cardiac contraction.
3. These are regulatory proteins.
4. Troponin is a complex of:
   1. Troponin-C is a Ca-binding component.
      1. It is not advised in AMI because this is not specific to myocardial muscles.
   2. Troponin-I is an inhibitory component.
   3. Troponin-T is a tropomyosin-binding component.
5. Troponins are present in myofibrils at a concentration of approximately 94% to 97%.
   1. Troponin cytoplasmic fraction is 3% to 6%.

What is the relationship between Troponins and muscle injury?

1. There are kits for  Troponin-I, but because of its three forms in circulation and their variation in concentration, different assays don’t produce reproducible results.
   1. Troponins remain in the blood circulation from 1 to 14 days after the onset of AMI.
2. Troponin-T has no cross-reactivity with skeletal muscle, so this assay is 100 % specific for cardiac disease.
3. Troponins help in the contraction of muscles, which is calcium-dependent, and there is an interaction between myosin and actin.
4. There are two cardiac troponins:
   1. Troponin-T.
   2. Troponin-I.
   3. These are highly specific for cardiac muscle injury.
5. Their role is just like CK-MB.
6. Troponins are more specific than CK-MB.
   1. Troponins will be nearly normal or slightly raised in noncardiac muscle injuries.

What are the advantages of troponins?

1. There is a quick release of troponins after the cardiac muscle injury (necrosis).
2. These are present for a longer period of time after the heart attack.
3. Troponins are measured by:
   1. Monoclonal antibody immunoassay.
   2. Enzyme-linked immunoassay.
   3. Monoclonal sandwich antibody qualitative technique.

What is the difference between Troponin and CK-MB?

What are the advantages of Troponin over CK-MB?

What are the normal Troponin-T and Troponin-I?

Source 1

• Cardiac Troponin-T = < 0.2 ng/mL
• Cardiac Troponin-I = < 0.03 mg/mL

Source 2

• Troponin-T = 0 to 0.1 µg/L
• Troponin-I = <3.1 µg/L

Source 3

• Troponin I = <0.35 ng/mL
  • Or <0.35 µg/L
• Troponin T = <0.2 ng/mL
  • Or <0.2 µg/L

What is the pattern of Troponin-T in acute myocardial infarction?

1. Raised even in the first 3 hours.
2. The peak level is 12 to 48 hours.
3. Remain elevated for up to 10 to 14 days.

How will you interpret Troponin?

1. Raised Troponin-T level establishes the diagnosis of AMI; even ECG or CK-MB is non-diagnostic (<50% of the cases).
2. It indicates irreversible necrosis of the myocardial muscles.
3. A serial troponin-T level normal, rules out the possibility of myocardial necrosis (AMI).
4. Troponins have replaced the CK-MB as the gold standard, replacing the late diagnosis of AMI with the raised level of LDH.
5. Troponin-T is as sensitive as CK-MB in the first 48 hours of the onset of AMI. It is >85% in concordance with CK-MB.
6. What is the Troponin-T sensitivity?

1. 1. Troponin-T sensitivity during 0 to 2 hours after the onset of chest pain = 33%
   2. Troponin-T sensitivity during 2 to 4 hours after the onset of chest pain = 50%.
   3. Troponin-T sensitivity during 4 to 8 hours after the onset of chest pain = 75%.
   4. Troponin-T sensitivity after 8 hours of the onset of chest pain = 100%.
2. Troponin-I is 13 times more abundant in the myocardium than CK-MB.
   1. Troponin-I remained increased for <9 days, while Troponin-T was increased for 14 days.
3. Troponins are increased in <50% of patients with acute pericarditis.
4. A level of troponins <0.5 ng/mL indicates no myocardial damage.
5. >2.0 ng/mL indicates some myocardial necrosis.

What is the universal definition of acute myocardial infarction?

1. The Troponin value of at least one of these is greater than 99% of the normal.
2. The rapid rise in CK-MB and falls to normal.
3. Evidence of ischemia.
4. Prominent Q-wave.
5. Elevation of ST-segment.

What are the causes of positive or raised Troponin-I levels?

1. Myocardial injury during surgery.
2. Small myocardial infarcts can be detected for up to 7 to 10 days.

What are the causes of positive or raised Troponin-T levels?

1. Acute myocardial infarction.
2. Pre-surgical myocardial infarction.
3. Unstable angina.
4. Non-ischemic diseases of the heart:
   1. Acute trauma involving muscles.
   2. Rhabdomyolysis.
   3. Polymyositis.
   4. Dermatomyositis.
   5. Chronic renal failure.
   6. Myocarditis.
   7. Pericarditis.
   8. Heart failure.
   9. Pulmonary embolism.
   10. Sepsis.
   11. Shock.
   12. Renal insufficiency.

How will you summarize Cardiac markers?

Questions and answers: