Main indications
Total creatine kinase increases with any muscle damage: after intense physical activity, with injuries and intramuscular injections, with inflammatory myopathies and muscular dystrophies, with hypothyroidism and rhabdomyolysis. A separate important application is to monitor the safety of statin therapy: these drugs rarely cause muscle damage, and if there are complaints of muscle pain and weakness, CPK testing is mandatory. A significant increase in this case requires discontinuation of the drug. Since the indicator increases after physical activity, blood is donated after abstaining from sports for at least a day, otherwise the result will be falsely high.
Why preparation is so important
The laboratory result is a number, but the correct number can only be obtained if the rules are followed. Eating changes the levels of glucose, lipids and a number of enzymes significantly; physical activity the day before increases CK and AST; smoking affects hormones; time of day is critical for cortisol and testosterone.
Therefore, a “bad analysis” often turns out to be a consequence of impaired preparation, and not an illness, and leads to unnecessary examinations and prescriptions.
General rules for donating blood
- on an empty stomach 8–12 hours, you can drink water
- Eliminate alcohol and intense exercise per day
- no smoking in an hour
- donate blood before physiotherapy, x-rays and massage
- Take medications in advance by agreeing with your doctor
- for hormones in women, take into account the day of the cycle
How to read the result
Reference values depend on the method and equipment of the laboratory, so it is correct to compare results only within the same laboratory. A deviation of a few percent from the normal limit in itself rarely matters - the overall picture and dynamics are important. It is up to the physician to interpret the analysis: an isolated indicator without a clinical context is often misleading.