High creatine kinase: what it means and what to do

A high creatine kinase means your muscles have released more of the enzyme than usual. Most of the time it is the training of the days before, and it comes down on its own. If you did not train, if it stays high or if it is very high, a doctor should see it.

What high creatine kinase means

Creatine kinase lives inside your muscles. When the fibres are stressed or torn, it leaks into your blood. A little of that happens with every hard workout: it is the sign that the muscle has worked.

Context matters more than the number. After a race or a heavy weights session it can rise a lot, and come down in about a week. Without exercise, or if it stays high, the cause needs looking for.

Above 1000 U/L the muscle damage is marked. It often recovers well, but a doctor should see it, because large damage can strain the kidneys.

What causes high creatine kinase

The most common come first.

Symptoms of high creatine kinase

High creatine kinase on its own causes no symptoms. If there are any, they come from the muscles. For example:

Dark urine after extreme exercise, with severe muscle pain, can mean rhabdomyolysis: call 112 or go to the emergency department.

High creatine kinase and high liver enzymes

After a hard workout it is not only CK that rises. AST and ALT, the liver enzymes, rise too, because they are also found in muscle. They can stay high for at least a week.

This often misleads: it looks like a liver problem, but the liver is fine. One clue is gamma GT, which comes from the liver and usually stays normal after exercise.

If your liver enzymes are high and you train, your doctor may ask for CK. If it is high too, your muscles are the most likely explanation. The simplest way to be sure is to repeat everything after a week of rest.

Which tests to read alongside it

These tests help show where it comes from.

What your result means

The upper end of the scale, in U/L.

What to do if your creatine kinase is high

It depends on how high it is and how you feel. Where to start:

Do not train hard again until the pain has gone and, if your CK was very high, until your doctor says so.

High creatine kinase: when to worry

Talk to your doctor if:

Frequently asked questions

High creatine kinase: when should I worry? If you did not train, if it stays high after a week of rest, if you feel weak or if it is above 1000 U/L. With dark urine or little urine, call 112 or go to the emergency department.

How long does CK take to come down after training? It usually returns to normal in about a week without hard exercise. After extreme exercise it can take longer.

High CK and high liver enzymes: is it my liver? Often not. After exercise they rise together, because AST and ALT are also found in muscle. If your gamma GT is normal and you trained, your muscles are the most likely explanation. Repeating the tests after rest confirms it.

Is high creatine kinase bad for the kidneys? Usually not. Only large muscle damage, such as rhabdomyolysis, can strain the kidneys. That is why your doctor checks creatinine when the value is very high.

Does creatine raise CK? Usually not. Creatine as a supplement can raise creatinine a little, which is a different test with a similar name. If your CK is high, training is still the most common reason.

Does Rosa test creatine kinase? No. Rosa measures ALT and AST, gamma GT and creatinine, which help read exercise and your kidneys. Your doctor orders CK when needed.

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