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Creatinine Test

What is a creatinine test?

This test measures creatinine levels in blood and/or urine. Creatinine is a waste product made by your muscles as part of regular, everyday activity. Normally, your kidneys filter creatinine from your blood and send it out of the body in your urine. If there is a problem with your kidneys, creatinine can build up in the blood and less will be released in urine. If blood and/or urine creatinine levels are not normal, it can be a sign of kidney disease.

Other names: blood creatinine, serum creatinine, urine creatinine

What is it used for?

A creatinine test is used to see if your kidneys are working normally. It's often ordered along with another kidney test called blood urea nitrogen (BUN) or as part of a comprehensive metabolic panel (CMP). A CMP is a group of tests that provide information about different organs and systems in the body. A CMP is frequently included in a routine checkup.

Why do I need a creatinine test?

You may need this test if you have symptoms of kidney disease. These include:

  • Fatigue
  • Puffiness around the eyes
  • Swelling in your feet and/or ankles
  • Decreased appetite
  • Frequent and painful urination
  • Urine that is foamy or bloody

You may also need this test if you have certain risk factors for kidney disease. You may be at higher risk for kidney disease if you have:

What happens during a creatinine test?

Creatinine can be tested in blood or urine.

For a creatinine blood test:

A health care professional will take a blood sample from a vein in your arm, using a small needle. After the needle is inserted, a small amount of blood will be collected into a test tube or vial. You may feel a little sting when the needle goes in or out. This usually takes less than five minutes.

For a creatinine urine test:

Your health care provider will ask you to collect all urine during a 24-hour period. Your health care provider or a laboratory professional will give you a container to collect your urine and instructions on how to collect and store your samples. A 24-hour urine sample test generally includes the following steps:

  • Empty your bladder in the morning and flush that urine away. Record the time.
  • For the next 24 hours, save all your urine passed in the container provided.
  • Store your urine container in the refrigerator or a cooler with ice.
  • Return the sample container to your health provider's office or the laboratory as instructed.

Will I need to do anything to prepare for the test?

You may be told to not eat cooked meat for 24 hours before your test. Studies have shown that cooked meat can temporarily raise creatinine levels.

Are there any risks to the test?

There is very little risk to having a blood test. You may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly.

There is no risk to having a urine test.

What do the results mean?

In general, high levels of creatinine in blood and low levels in urine indicate kidney disease or another condition that affects kidney function. These include:

But abnormal results don't always mean kidney disease. The following conditions can temporarily raise creatinine levels:

  • Pregnancy
  • Intense exercise
  • A diet high in red meat
  • Certain medicines. Some medicines have side effects that raise creatinine levels.

If you have questions about your results, talk to your health care provider.

Is there anything else I need to know about a creatinine test?

Your health care provider may also order a creatinine clearance test. A creatinine clearance test compares the level of creatinine in blood with the level of creatinine in urine. A creatinine clearance test may provide more accurate information on kidney function than a blood or urine test alone.

References

  1. Hinkle J, Cheever K. Brunner & Suddarth's Handbook of Laboratory and Diagnostic Tests. 2nd Ed, Kindle. Philadelphia: Wolters Kluwer Health, Lippincott Williams & Wilkins; c2014. Creatinine, Serum; p. 198.
  2. Hinkle J, Cheever K. Brunner & Suddarth's Handbook of Laboratory and Diagnostic Tests. 2nd Ed, Kindle. Philadelphia: Wolters Kluwer Health, Lippincott Williams & Wilkins; c2014. Creatinine, Urine; p. 199.
  3. Kids Health from Nemours [Internet]. Jacksonville (FL): The Nemours Foundation; c1995–2019. Urine Test: Creatinine [cited 2019 Aug 28]; [about 3 screens]. Available from: https://kidshealth.org/en/parents/test-creatinine.html
  4. Lab Tests Online [Internet]. Washington D.C.; American Association for Clinical Chemistry; c2001–2019. 24-Hour Urine Sample [updated 2017 Jul 10; cited 2019 Aug 28]; [about 2 screens]. Available from: https://labtestsonline.org/glossary/urine-24
  5. Lab Tests Online [Internet]. Washington D.C.; American Association for Clinical Chemistry; c2001–2019. Creatinine [updated 2019 Jul 11; cited 2019 Aug 28]; [about 2 screens]. Available from: https://labtestsonline.org/tests/creatinine
  6. Lab Tests Online [Internet]. Washington D.C.; American Association for Clinical Chemistry; c2001–2019. Creatinine Clearance [updated 2019 May 3; cited 2019 Aug 28]; [about 2 screens]. Available from: https://labtestsonline.org/tests/creatinine-clearance
  7. Mayo Clinic [Internet]. Mayo Foundation for Medical Education and Research; c1998–2019. Creatinine test: About; 2018 Dec 22 [cited 2019 Aug 28]; [about 3 screens]. Available from: https://www.mayoclinic.org/tests-procedures/creatinine-test/about/pac-20384646
  8. National Heart, Lung, and Blood Institute [Internet]. Bethesda (MD): U.S. Department of Health and Human Services; Blood Tests [cited 2019 Aug 28]; [about 3 screens]. Available from: https://www.nhlbi.nih.gov/health-topics/blood-tests
  9. National Kidney Foundation [Internet]. New York: National Kidney Foundation Inc., c2019. A to Z Health Guide: Creatinine: What is it? [cited 2019 Aug 28]; [about 3 screens]. Available from: https://www.kidney.org/atoz/content/what-creatinine
  10. UF Health: University of Florida Health [Internet]. Gainesville (FL): University of Florida; c2019. Creatinine blood test: Overview [updated 2019 Aug 28; cited 2019 Aug 28]; [about 2 screens]. Available from: https://ufhealth.org/creatinine-blood-test
  11. UF Health: University of Florida Health [Internet]. Gainesville (FL): University of Florida; c2019. Creatinine clearance test: Overview [updated 2019 Aug 28; cited 2019 Aug 28]; [about 2 screens]. Available from: https://ufhealth.org/creatinine-clearance-test
  12. UF Health: University of Florida Health [Internet]. Gainesville (FL): University of Florida; c2019. Creatinine urine test: Overview [updated 2019 Aug 28; cited 2019 Aug 28]; [about 2 screens]. Available from: https://ufhealth.org/creatinine-urine-test
  13. University of Rochester Medical Center [Internet]. Rochester (NY): University of Rochester Medical Center; c2019. Health Encyclopedia: Creatinine (Blood) [cited 2019 Aug 28]; [about 2 screens]. Available from: https://www.urmc.rochester.edu/encyclopedia/content.aspx?ContentTypeID=167&ContentID=creatinine_serum
  14. University of Rochester Medical Center [Internet]. Rochester (NY): University of Rochester Medical Center; c2019. Health Encyclopedia: Creatinine (Urine) [cited 2019 Aug 28]; [about 2 screens]. Available from: https://www.urmc.rochester.edu/encyclopedia/content.aspx?contenttypeid=167&contentid=creatinine_urine
  15. UW Health [Internet]. Madison (WI): University of Wisconsin Hospitals and Clinics Authority; c2019. Health Information: Creatinine and Creatinine Clearance: How It Is Done [updated 2018 Oct 31; cited 2019 Aug 28]; [about 5 screens]. Available from: https://www.uwhealth.org/health/topic/medicaltest/creatinine-and-creatinine-clearance/hw4322.html#hw4342
  16. UW Health [Internet]. Madison (WI): University of Wisconsin Hospitals and Clinics Authority; c2019. Health Information: Creatinine and Creatinine Clearance: How to Prepare [updated 2018 Oct 31; cited 2019 Aug 28]; [about 4 screens]. Available from: https://www.uwhealth.org/health/topic/medicaltest/creatinine-and-creatinine-clearance/hw4322.html#hw4339
  17. UW Health [Internet]. Madison (WI): University of Wisconsin Hospitals and Clinics Authority; c2019. Health Information: Creatinine and Creatinine Clearance: Test Overview [updated 2018 Oct 31; cited 2019 Aug 28]; [about 2 screens]. Available from: https://www.uwhealth.org/health/topic/medicaltest/creatinine-and-creatinine-clearance/hw4322.html

The medical information provided is for informational purposes only, and is not to be used as a substitute for professional medical advice, diagnosis or treatment. Please contact your health care provider with questions you may have regarding medical conditions or the interpretation of test results.

In the event of a medical emergency, call 911 immediately.