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Total creatine kinase in the blood
Medical expert of the article
Last reviewed: 05.07.2025
Reference values (norm) of creatine kinase activity in blood serum: men - 52-200 IU/l, women - 35-165 IU/l.
Creatine kinase reversibly catalyzes the phosphorylation of creatine. The skeletal muscles and cardiac muscle are the richest in creatine kinase, and there is less of it in the brain, thyroid gland, uterus, and lungs. The following creatine kinase isoenzymes have the greatest diagnostic value: KK-MM (muscle), KK-MB (cardiac), and KK-BB (brain). Increased creatine kinase activity in the blood serum occurs due to the release of the enzyme from cells when they are damaged.
In myocardial infarction, the release of creatine kinase from the heart muscle into the blood serum precedes other enzymes, so the determination of creatine kinase has found the widest application for early diagnostics. Increased creatine kinase activity is detected in 95-99% of patients with myocardial infarction. Creatine kinase increases as early as 2-4 hours after the onset of the disease, reaching a maximum after 24-36 hours (5-20 times higher than normal). It should be emphasized that creatine kinase activity returns to normal relatively quickly (on the 3rd-6th day).
Changes in enzyme activity in myocardial infarction
Enzyme |
Start of increase in activity, h |
Maximum increase in activity, h |
Return to normal, days |
Magnification factor, times |
AST KK LDG |
4-6 2-4 8-10 |
24-48 24-36 48-72 |
4-7 3-6 8-9 |
2-20 3-30 2-4 |