Health Information

For the right diagnosis of a particular disease, it is always better to estimate a few (three or more) serum enzymes, instead of a single enzyme. Examples of enzyme patterns in important diseases are given here.

Enzymes in myocardial infarction

The enzymes – namely creatine phosphokinase (CPK), aspartate transaminase (AST) and lactate dehydrogenase (LDH) – are important in the diagnosis of myocardial infarction (MI).

Creatine phosphokinase (preclsely isoenzyme MB) is the first enzyme to be released into circulation within 6-18 hours after the infarction. Therefore, CPK estimation is highly useful for the early diagnosis of MI. This enzyme reaches a peak value within 24-30 hours and returns to normal level by the 2nd or 3rd day.

Aspartate transaminase (AST or SGOT) rises sharply after CPK, and reaches a peak within 48 hours of the myocardial infarction. AST takes 4-5 days to return to normal level.

Lactate dehydrogenase (LDH1) generally rises from the second day after infarction, attains a peak by the 3rd or 4th day and takes about 10-15 days to reach normal level. Thus, LDH is the last enzyme to rise and also the last enzyme to return to normal level in MI.

[Note : Cardiac troponins (proteins but not enzymes) are in recent use for the diagnosis of MI. The concentration of troponin T (TnT2) shots up in serum within 4 hours of MI and remains elevated for about 2 weeks].

Enzymes in liver diseases

The following enzymes – when elevated in serum – are useful for the diagnosis of liver dysfunction due to viral hepatitis (jaundice), toxic hepatitis, cirrhosis and hepatic necrosis
1. Alanine transaminase
2. Aspartate transaminase
3. Lactate dehydrogenase
The enzymes that markedly increase in intrahepatic and extrahepatic cholestasis are alkaline phosphatase, and 5’-Nucleotidase. Serum gamma glutamyl transpeptidase is useful in the diagnosis of alcoholic liver diseases.