Creatinine and Creatinine Clearance Tests: What’s Their Purpose?

Creatinine and Creatinine Clearance Tests: What’s Their Purpose?

One of the amazing facts about our kidneys is that just one of these organs pumps over 50 gallons of blood every day. Kidneys are responsible for removing waste products from our blood and producing urine. These amazing and vital organs control the levels of many substances in our blood.

You got the point: it’s crucial to take good care of our kidneys’ health. They say you cannot live without love, but kidneys might be even more important.

To keep our kidneys healthy over the years, there are specific actions we can take that need to get in our routine. We should have enough sleep at night, avoid smoking and alcohol, do some workouts, and so on.

However, we also shouldn’t forget about the creatinine and creatinine clearance tests. Such tests will tell us how well our kidneys are working, and thanks to, we can now learn more!

What is creatinine?

Creatine is a substance that forms when our body changes food into energy through the metabolism process. Therefore, creatine will be broken down into creatinine. The kidneys are responsible for eliminating creatinine through urine.

If the level of creatinine in your urine decreases while its level in the blood increases, it means that your kidneys don’t work as they were programmed by the Almighty God.

Three tests can be done:

  • Blood creatinine level
  • Creatinine clearance
  • Blood urea nitrogen-to-creatinine ratio

Such tests are done for multiple purposes. First of all, doctors need to see if the patient’s kidneys work as they should. They can also find out if there are any changes in a kidney disease through the same tests. If, on the other hand, you take medicines that can lead to kidney damage, doctors might choose to run those tests in order to see how well the kidneys work.

Another argument why the three tests mentioned above are done is to check for signs of severe dehydration.

How to prepare for the tests

The healthcare professional or doctor might ask you to do the following in case you need to prepare for the aforementioned tests:

  • Avoid eating over 8 ounces of meat, especially beef, as well as other protein for 24 hours before the start of the blood creatinine test and even during the creatinine clearance urine test.
  • Avoid any strenuous exercise for 48 hours before you have the tests
  • Drink lots of fluids if it is needed to collect your urine for 24 hours. However, you must avoid tea and coffee, as they will cause your body to pass more urine than usual.

You might also have to collect urine over the course of 24 hours, which means that you will be given a large container where about 1 gallon can fit.

Probably the most important step is to continuously communicate with your doctor. You must inform him about each and every medicine, vitamin, supplement, and herbal remedy that you might take. Depending on what you get in your body, some problems during the tests might occur. For some of them, you might have to stop taking them ASAP, but your doctor will inform you the best about what you need to know.

Doctors asking for a urine sample from their patients don’t represent anything unusual. By doing so, doctors will have the chance to diagnose or rule out specific health conditions. Waste products that are filtered out of our bodies are components of our urine, and any unusual components might tell doctors what’s wrong with the patient’s body.


Even since he was a child, Cristian was staring curiously at the stars, wondering about the Universe and our place in it. Today he's seeing his dream come true by writing about the latest news in astronomy. Cristian is also glad to be covering health and other science topics, having significant experience in writing about such fields.

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