What Is a Creatinine Urine Test?
Creatinine is a chemical waste product produced by muscle
metabolism. When your kidneys are functioning normally, they filter creatinine
and other waste products out of your blood. These waste products are removed
from your body through urination.
A creatinine urine test measures the amount of creatinine in your
urine. The test can help your doctor evaluate how well your kidneys are
functioning. This is useful for diagnosing or ruling out kidney disease
and other conditions affecting the kidneys.
Your doctor may use a random urine sample to test for creatinine.
However, they’ll order a urine 24-hour volume test in most cases. As the name
suggests, this creatinine urine test measures the amount of urine produced in a
day. It isn’t a painful test, and there aren’t any risks associated with it.
How Do I Prepare for the 24-Hour Volume Test?
The 24-hour volume test is noninvasive and involves only the
collection of urine. You’ll be given one or more containers for collecting and
storing urine. Since this test involves collecting and storing urine for a
24-hour period, you may want to consider scheduling the test for a day when
you’re at home.
Before the test, you should do the following:
- Tell your doctor if you’re pregnant or think you
may be pregnant.
- Tell your doctor about any supplements or prescription
and over-the-counter medications you’re taking. Some supplements and drugs can
interfere with the test results. Your doctor can tell you which ones to avoid.
- Avoid certain foods or beverages if your doctor
advises you to do so.
- Ask your doctor if you need to begin the test at
a particular time of day.
- Make sure you understand when and where you
should return the container of urine.
How Is the 24-Hour Volume Test Performed?
To perform the test, you’ll use a special container to collect your
urine for the next 24 hours. Ask your doctor how to collect urine if you’re
unsure how to do so. Failure to follow instructions could lead to false
results, which means you may have to repeat the test.
The test should begin at a specific time and end at the same time
on the following day.
- On the
first day, don’t collect the urine from your first time urinating. However,
make sure you note and record the time. This will be the start time of the 24-hour
- Collect all your urine for the next 24 hours. Keep
the storage container refrigerated throughout the process.
- On the
second day, try to urinate around the same time that the test started on the
- When the 24-hour period is over, cap the
container and promptly return it to the lab or doctor’s office as instructed.
- Be sure to tell your doctor if you were unable
to follow all the instructions. You should report any missed urine, spilled
urine, or urine collected after the 24-hour time period ended. You should also
tell them if you were unable to store the container of urine in a cool place.
Interpreting the Results of a Creatinine
There are natural variations in creatinine output due to age and
body mass. The more muscular you are, the higher your range will be. It’s also
important to note that not all laboratories use the same values. Results are
dependent on the proper collection of your urine sample.
Normal urine creatinine values generally range from 500 to 2,000
mg per day. Creatinine values that fall outside the normal range may be an
- kidney disease
- kidney infection
- kidney failure
- urinary tract obstruction, such as kidney stones
- late-stage muscular
dystrophy, which is a group of diseases that damage and weaken your muscles
- myasthenia gravis,
which is an autoimmune disease that causes muscle weakness
Abnormal values can also occur in people who have diabetes or a diet
that’s high in meat or other proteins.
It’s very difficult to evaluate the test results on your own. You
should discuss your results with your doctor.
Depending on your results, your doctor may order a serum
creatinine test. This is a type of blood test that measures the amount of
creatinine in your blood. Your doctor may use it to help confirm a diagnosis.