BIOCHEMICAL MARKERS FOR MYOCARDIAL INFARCTION

Diagnosis is based on blood levels of proteins that are leaked out from irreversibly damaged myocyte
These molecules include –

- Cardiac specific troponins T and I (cTnT & cTnI)

- MB fraction of creatine kinase (CK-MB)
- Lactate Dehydrogenase (LDH)
- Myoglobin
Cardiac-specific troponins (cTn)
- Most sensitive & specific biomarkers of MI
- Troponins – regulate calcium mediated contraction of cardiac and skeletal muscle
- They are Cardiac troponin T (cTnT) & Cardiac troponin I (cTnI)
- Not found in the blood normally
- Post MI – begin to rise at 3-12 hours
- cTnT levels peak – 12-48 hours
- cTnI levels peak – 24 hours
Creatine kinase
- Enzyme present in brain, myocardium and skeletal muscle
- It is a dimer composed of two isoforms designated as “M” and “B”.
- MM homodimer – present in cardiac muscle and skeletal muscle
- BB homodimer –present in brain, lung and many other tisuues
- MB heterodimer – present in cardiac muscle (lesser amount in skeletal muscle)
- MB form of Creatine kinase is sensitive but not specifc
- Rises within 3-12 hrs of onset of MI,
- Peaks in approximately 24 hrs
- Returns to normal by 72 hrs
But elevated Troponin levels persists for approximately 10 to 14 days after acute MI
Lactate dehydrogenase (LDH)
- Lacks sensitivity
- Enzyme is present in various tissues – myocardium, skeletal muscle, kidneys, liver, lungs and red blood cells
- It has 2 forms LDH 1 & 2.
- LDH 1 – more myocardial specific
- LDH1:LDH2 > 1 — Indicates MI
- LDH peaks in 3 days and persists for 4 to 7 days
Myoglobin
- First marker to be elevated after MI
- Lacks cardiac specificity
- Excreted rapidly in urine
- Its level return to normal within 24 hrs post acute MI

SUMMARY OF MARKERS OF MI

References

Vinay kumar, Abul K.Abbas, Nelson Fausto, Jon C. Aster. Robbins and Cotran Pathologic basis of disease. 9th edition.
Harsh mohan. Text book of Pathology.8th edition.2019

BIOCHEMICAL MARKERS FOR MYOCARDIAL INFARCTION

Diagnosis is based on blood levels of proteins that are leaked out from irreversibly damaged myocyte

These molecules include –

Cardiac specific troponins T and I (cTnT & cTnI)

MB fraction of creatine kinase (CK-MB)

Lactate Dehydrogenase (LDH)

Myoglobin

Cardiac-specific troponins (cTn)

Most sensitive & specific biomarkers of MI

Troponins – regulate calcium mediated contraction of cardiac and skeletal muscle

They are Cardiac troponin T (cTnT) & Cardiac troponin I (cTnI)

Not found in the blood normally

Post MI – begin to rise at 3-12 hours

cTnT levels peak – 12-48 hours

cTnI levels peak – 24 hours

Creatine kinase

Enzyme present in brain, myocardium and skeletal muscle

It is a dimer composed of two isoforms designated as “M” and “B”.

MM homodimer – present in cardiac muscle and skeletal muscle

BB homodimer –present in brain, lung and many other tisuues

MB heterodimer – present in cardiac muscle (lesser amount in skeletal muscle)

MB form of Creatine kinase is sensitive but not specifc

Rises within 3-12 hrs of onset of MI,

Peaks in approximately 24 hrs

Returns to normal by 72 hrs

But elevated Troponin levels persists for approximately 10 to 14 days after acute MI

Lactate dehydrogenase (LDH)

Lacks sensitivity

Enzyme is present in various tissues – myocardium, skeletal muscle, kidneys, liver, lungs and red blood cells

It has 2 forms LDH 1 & 2.

LDH 1 – more myocardial specific

LDH1:LDH2 > 1 — Indicates MI

LDH peaks in 3 days and persists for 4 to 7 days

Myoglobin

First marker to be elevated after MI

Lacks cardiac specificity

Excreted rapidly in urine

Its level return to normal within 24 hrs post acute MI

SUMMARY OF MARKERS OF MI

References

Vinay kumar, Abul K.Abbas, Nelson Fausto, Jon C. Aster. Robbins and Cotran Pathologic basis of disease. 9th edition.

Harsh mohan. Text book of Pathology.8th edition.2019