Creatinine Test - Understand the Test & Your Results

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:
Type 1 or type 2 diabetes
High blood pressure
A family history of kidney disease
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:
Autoimmune diseases
Bacterial infection of the kidneys
Blocked urinary tract
Heart failure
Complications of diabetes
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.
Learn more about laboratory tests, reference ranges, and understanding results .
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
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.
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.
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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
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
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