Are you wondering what causes high creatinine levels? Maybe you got a recent blood test and you are looking at some of the things that are flagged as high or low and yours says high creatinine.  Creatinine is a way to measure your kidney function.  In this article, we look at what causes creatinine levels to go up and down and what the actual test is measuring.
Creatinine is a chemical byproduct of creatine, which comes from muscle tissue.  Mostly, creatine helps deliver energy to the muscle when higher energy demands are present.  You have probably heard of creatine in terms of building muscle, body building, and overall athletic performance.  This is the same thing that we are talking about.  However, don't confuse creatine with creatinine. 

Creatine actually turns into creatinine via the enzyme creatinine kinase.  Creatine it's continually being produced by the liver and therefore its production is said to be constant.  Because of that ongoing production of creatine, there's also an ongoing production of creatinine.  The creatinine is eliminated from the body via the kidneys.  Since we know where it comes from and we know how it's eliminated from the body, we know why someone might have high levels or what causes high levels of creatinine.
Let me give you a little more context and detail so you can fully grasp this for your own health.  We said that creatinine comes from creatine, which comes from muscle. Therefore, the more muscle mass you have, and the bigger you are overall, the more creatinine you are going to end up with. 

Now, the general utility of the creatinine test is to look at your kidney function or estimated GFR.  GFR stands for glomerular filtration rate.  The Glomeruli are little filtration systems within the kidney itself.  How well those glomeruli filtration systems are working is said to be related to the creatinine.

The higher your blood creatinine level, the lower your kidney filtration rate because the creatinine goes out through the kidneys in the urinary system.  If there's a problem in those filtration systems, the blood creatinine goes up. So that's how we generally think about this test.  However, there are some problems or some ways that this test can be a bit misleading. 
The first being, it doesn't really factor in your actual weight.  If you are really really small, really really big, or even slightly above or below average it skews the results.  It skews the glomerular filtration rate.  Almost always, when you look at the GFR, there's a little 'e' next to it.  That 'e' stands for estimated.  It's an estimate because it doesn't factor in your weight. It also does not factor in your gender (some labs do) , which is also important because males tend to have more muscle mass than females.

So this is really important.  There are actual calculators that will factor in your weight and gender.  With this you can get a more appropriate measurement.  There are also other tests that don't use creatinine to measure your kidney function.

The other thing that can sometimes happen when looking at causes of high creatinine levels is recent high intensity exercise close to the test.  Because creatinine levels are related to muscle, muscle cells damage can cause higher amounts of creatinine in the blood.  Therefore with exercise you can see the kidney function look a little bit off.  This can happen one to two days away from a high intensity exercise activity.  The same thing can happen with liver enzymes. 

Exercise and Elevated Liver Enzymes

Now, if you are regularly doing exercise and this is just part of your routine, we wouldn't expect much affect on the creatinine level.  If it's something new and really intense for your body, that's when it will influence your creatinine level.  It will cause a high creatinine.  The other thing is if you are taking creatine on a regular basis, it will raise your creatinine levels as well. 

Of course, the most concerning reason for high creatine levels is you actually do have poor kidney functions.  So that's the most obvious thing to look at.  There are other reasons not mentioned that can cause this that have nothing to do with your actual kidney function too.

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