Creatinine is a waste product of creatine, which is a chemical that the body uses to supply the muscles with energy. Creatinine is formed as a result of the natural breakdown of your muscle tissue and can then enter the blood.
Under normal conditions, your kidneys filter creatinine from your blood. Creatinine leaves the body through urine.
The creatinine clearance is a test that allows your doctor to assess your kidney function. It is usually measured using both a blood test and a urine test. The creatinine clearance can also be estimated from a mathematical formula that will use the blood levels of creatinine along with other factors (such as your age, race, and gender).
Creatinine clearance testing determines your overall glomerular filtration rate (GFR), which reflect how well your kidneys are cleaning your blood.
Anyone can be at risk for a kidney disease at some point in time. However, some people are more at risk than others for developing kidney disease. You are at a higher risk for developing kidney disease if you are over 60 years old or if you have:
Kidney disease tends to be silent and there are no symptoms in the early stages. However, as the disease progresses, you may experience swelling, fatigue, breathing problems, changes in how often you urinate, loss of appetite, nausea, itching, and a darkening of the skin.
Your doctor or nurse will give you the test instructions. You will need to collect your urine for 24 hours. Then, a blood sample will be drawn from you.
Your doctor may ask you to stop some medications temporarily if they are believed to affect the test accuracy. These medications include antibiotics and stomach acid pills. You should tell your doctor what other medications you have been taking. Also, DO NOT stop taking any medications before talking to your doctor.
The urine test involves only normal urination. You should not feel any pain or discomfort during this part of the test.
The blood test involves inserting a needle to draw a blood sample. Patients’ feelings vary from mild pain to a prick or stinging feeling. It is also possible to feel some throbbing or have a slight bruise. All of this discomfort goes away quickly.
Collecting urine samples throughout the entire day is important for the accuracy of the test. For this reason, skipping one urine sample may affect the results. Please call your doctor’s office to find out whether you should continue collecting or stop and start all over again the next day.
The reported ranges of creatinine clearance test results (usually measured as milliliters per minute) vary slightly between laboratories, depending on the different measurements or test samples. The normal range, however, is between 97 and 137 ml/min for males, and 88 and 128 ml/min for females.
An abnormal creatinine clearance test means that creatinine is not filtered properly by your kidneys. When kidneys slow down, creatinine levels increase. This means you could be at risk of having kidney problems.
You should talk to your doctor about what your test results mean.
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This information is provided by the Cleveland Clinic and is not intended to replace the medical advice of your doctor or healthcare provider. Please consult your healthcare provider for advice about a specific medical condition. This document was last reviewed on: 12/21/2016