Hi Doctor: I’m a 60 year old woman who is a marathoner. I have ran 8 marathons in the last 10 months and several short races. I was tired a lot and decided to see my regular doctor. My CK numbers read 261. and CKMB 8.1. I rested a few days and the CK went down to 180. I ran another long training run and was tested again and my CK was 216. How long do I need to rest to get my numbers below 160? I am also drinking lots of water now because I was severely dehydrated. I do not drink alcohol or smoke or anything like that. Is this kind of reading normal for long distance ultra runners?

The creatine phosphokinase (CPK or CK) is a muscle enzyme test that is elevated any time there is any muscle injury.  In the case of strenuous exercise, the elevation depends on how strenuous the exercise and the muscles injured.  Each person is unique, so there is likely no way to predict how long it takes to normalize the muscle test.  Hydration will prevent kidney injury from occurring.  Marked injury to the muscle with “rhabdomyolysis” will cause red urine and could cause kidney injury.  The elevation of CK tests is never normal but may be an expected finding in people who regularly engage in strenuous physical activity.


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