Creatinine and Creatinine Clearance
How To Prepare
Do not do any strenuous exercise for 2
days (48 hours) before having creatinine tests.
Do not eat more
than 8 oz (227 g) of meat,
especially beef, or other protein for 24 hours before the blood creatinine test
and during the creatinine clearance urine test.
Be sure to
drink enough fluids during the 24-hour urine collection, but do not drink coffee
or tea. These are
diuretics that cause your body to pass more
How It Is Done
Collecting the blood sample
professional drawing blood will:
- Wrap an elastic band around your upper arm to
stop the flow of blood. This makes the veins below the band larger so it is
easier to put a needle into the vein.
- Clean the needle site with
- Put the needle into the vein. More than one needle stick
may be needed.
- Attach a tube to the needle to fill it with
- Remove the band from your arm when enough blood is
- Put a gauze pad or cotton ball over the needle site as
the needle is removed.
- Put pressure on the site and then put on a
Collecting the 24-hour urine sample
- You start collecting your urine in the
morning. When you first get up, empty your bladder but do not save this urine.
Write down the time that you urinated. This marks the beginning of your 24-hour collection period.
- For the next 24 hours, collect all your urine.
Your doctor or lab will usually provide you with a large container that holds
about 1 gal (4 L). The container has a small amount of preservative in it.
Urinate into a small, clean container and then pour the urine into the large
container. Do not touch the inside of the container with your
- Keep the large container in the refrigerator for the 24
- Empty your bladder for the final time at or just before the
end of the 24-hour period. Add this urine to the large container, and record the
- Do not get toilet paper, pubic hair, stool (feces), menstrual
blood, or other foreign matter in the urine sample.