The creatinine clearance test is used to assess kidney function by examining urine and blood samples to determine the amount of creatinine, a waste substance that the kidneys filter out of the blood. The test is useful in identifying the presence of kidney disease or dysfunction.
The creatinine clearance test comprises two stages involving the collection of urine samples over 24 hours and the drawing blood. The samples are analyzed to determine the amount of creatinine filtered by the kidneys within the 24-hour. The test results are then used to calculate the creatinine clearance level, which estimates the glomerular filtration rate (GFR). The provider will utilize the GFR to establish how well the kidneys function
Why do I need to have the creatinine clearance test?
Kidney disease can affect anyone at any stage in life, but certain individuals are at higher risk of developing kidney problems than others. Here are the factors that can increase the risk of kidney disease:
- Diabetes
- Familyhistory of kidney disorders
- Age (higher risk after age 60)
- High blood pressure (hypertension)
- Heritage
Why is the creatinine clearance test done?
The creatinine clearance test is performed to verify the kidney function level indicated by the eGFR measurement. Healthcare providers utilize this test to determine the effectiveness of the kidneys in performing their functions. The results of the test can aid in diagnosing kidney disease.
How to prepare for the creatinine clearance test?
Before conducting the creatinine clearance test, the healthcare provider will provide detailed instructions. The test involves collecting urine for 24 hours and drawing a blood sample.
Your healthcare provider will supply you with a container for collecting the urine sample and guide proper storage during the 24-hour collection period. It is essential to adhere to the instructions given by your provider and to ensure that urine is collected throughout the test. Failure to comply with the instructions may necessitate repeating the test.
The healthcare provider may also ask you to discontinue certain medications, which will be done under their direct supervision. This is because some medications can impact the accuracy of the test results, so temporarily suspending their use may be necessary. These medications could include:
- Stomach acid pills
- Antibiotics
It is important to inform your healthcare provider of any medication you are taking and to ensure a comprehensive list of all medications is documented in your medical records.
Is it necessary to fast (not eat) before the creatinine clearance test?
Generally, there are no dietary restrictions before or during the creatinine clearance test. However, your healthcare provider may request that you refrain from eating overnight or abstain from consuming meat prior to the test. This is because meat contains higher levels of creatine, which can result in elevated creatinine levels during the test, leading to altered test results.
What happens during the creatinine clearance test?
You will do the creatinine clearance test over the course of 24 hours. During this time, you will collect your urine each time you urinate. This will give your healthcare provider a good idea of your creatinine levels throughout the day.
Regarding the creatinine clearance test, it is essential to follow the instructions provided by the healthcare provider strictly. These instructions will include directions for storing the urine sample and the location for submitting the sample once the test is completed.
Following the 24-hour urine collection, you will be required to have a blood draw to measure the creatinine level in the bloodstream, known as serum creatinine. The results from both the urine and blood tests will then be inputted into a mathematical formula to calculate the creatinine clearance. This rate informs the doctor about how effectively the kidneys filter waste from the bloodstream.
