Creatinine

Also Known As

Creat

Blood Creatinine

Serum Creatinine

Urine Creatinine

Formal Name

Creatinine

This article was last reviewed on

August 31, 2015.

This article waslast modified on May 3, 2019.

At a Glance

Why Get Tested?

To evaluate the health of your kidneys; to help diagnose kidney disease; to monitor treatment for kidney disease

When To Get Tested?

Routinely as part of a comprehensive or basic metabolic panel; when your have signs and symptoms that may be due to kidney disease or damage or when you have a condition that may affect your kidneys and/or be worsened by kidney dysfunction; at intervals to monitor treatment for kidney disease or kidney function while on certain medications

Sample Required?

A blood sample drawn from a vein in your arm and/or a 24-hour urine sample

Test Preparation Needed?

You may be instructed to fast overnight or refrain from eating cooked meat; some studies have shown that eating cooked meat prior to testing can temporarily increase the level of creatinine.

What is being tested?

Creatinine is a waste product produced by muscles from the breakdown of a compound called creatine. Creatinine is removed from the body by the kidneys, which filter almost all of it from the blood and release it into the urine. This test measures the amount of creatinine in the blood and/or urine.

Creatine is part of the cycle that produces energy needed to contract muscles. Both creatine and creatinine are produced by the body at a relatively constant rate. Since almost all creatinine is filtered from the blood by the kidneys and released into the urine, blood levels are usually a good indicator of how well the kidneys are working. The quantity produced depends on the size of the person and their muscle mass. For this reason, creatinine concentrations will be slightly higher in men than in women and children.

Results from a blood creatinine test may be used in combination with results from other tests, such as a 24-hour urine creatinine test, to perform calculations that are used to evaluate kidney function. See the "How is it used?" section under Common Questions.

How is the sample collected for testing?

A blood sample is drawn from a vein in the arm. A 24-hour urine sample may also be collected, in which all urine produced during 24 hours is saved. Sometimes a single, random urine sample may be collected and tested.

Is any test preparation needed to ensure the quality of the sample?

You may be instructed to fast overnight or refrain from eating cooked meat; some studies have shown that eating cooked meat prior to testing can temporarily increase the level of creatinine. If a 24-hour urine sample is being collected, it is important to save all of the urine produced during that time period.

Common Questions

How is it used?
The creatinine blood test is used to assess kidney function. It is frequently ordered along with a BUN (blood urea nitrogen) test or as part of a basic or comprehensive metabolic panel (BMP or CMP), groups of tests that are performed to evaluate the function of the body's major organs. BMP or CMP tests are used to screen healthy people during routine physical exams and to help evaluate acutely or chronically ill people in the emergency room and/or hospital. Sometimes, creatinine may be performed as part of a renal panel to evaluate kidney function.

Creatinine is a waste product produced by muscles from the breakdown of a compound called creatine. Almost all creatinine is filtered from the blood by the kidneys and released into the urine, so blood levels are usually a good indicator of how well the kidneys are working.

The kidneys are a pair of bean-shaped organs that are located at the bottom of the ribcage in the right and left sides of the back. Within them are about a million tiny blood filtering units called nephrons. In each nephron, blood is continually filtered through a microscopic cluster of looping blood vessels, called a glomerulus. The glomerulus allows the passage of water and small molecules but retains blood cells and larger molecules. Attached to each glomerulus is a tiny tube (tubule) that collects the fluid and molecules that pass through the glomerulus and then reabsorbs what can be used by the body. The remaining waste forms urine.

If the creatinine and BUN tests are found to be abnormal or if someone has an underlying disease that is known to affect the kidneys, such as diabetes or high blood pressure, then creatinine and BUN tests may be used to monitor for kidney dysfunction and the effectiveness of treatment. Blood creatinine and BUN tests may also be ordered to evaluate kidney function prior to some procedures, such as a CT (computed tomography) scan, that may require the use of drugs that can damage the kidneys.

Results from creatinine tests may be used in calculations that help assess kidney function:

Blood creatinine measurements, along with age, weight, and sex, are used to calculate the estimated glomerular filtration rate (eGFR), which is used as a screening test to look for evidence of early kidney damage.

Blood and urine creatinine levels may be used to calculate a creatinine clearance. This test measures how effectively the kidneys are filtering small molecules like creatinine out of the blood.

Urine creatinine may also be used with a variety of other urine tests as a correction factor. The concentration (or dilution) of urine varies throughout the day, with more or less liquid being released in addition to the body's waste products. Since creatinine is produced and removed at a relatively constant rate, the amount of urine creatinine can be compared to the amount of another substance being measured. This stable excretion rate is useful when evaluating both 24-hour urine samples and random urine samples. Examples include:

Urine albumin/creatinine ratio (ACR). This more accurately determines how much albumin is escaping from the kidneys into the urine. It is used to screen people with chronic conditions, such as diabetes and high blood pressure (hypertension) that put them at an increased risk of developing kidney disease.

Urine protein/creatinine ratio (UP/CR). This may be used to monitor a person with known kidney disease or damage or to screen people on a regular basis when they are taking a medication that may affect their kidney function.
When is it ordered?
Creatinine may be ordered routinely as part of a comprehensive or basic metabolic panel during a health examination. It may be ordered when someone is acutely ill and/or when a health practitioner suspects that a person's kidneys are not working properly. Some signs and symptoms of kidney dysfunction include:

Fatigue, lack of concentration, poor appetite, or trouble sleeping

Swelling or puffiness, particularly around the eyes or in the face, wrists, abdomen, thighs or ankles

Urine that is foamy, bloody, or coffee-colored

A decrease in the amount of urine

Problems urinating, such as a burning feeling or abnormal discharge during urination, or a change in the frequency of urination, especially at night

Mid-back pain (flank), below the ribs, near where the kidneys are located

High blood pressure

The creatinine blood test may be ordered, along with a BUN test and urine albumin, at regular intervals when someone has a known kidney disorder or has a disease that may affect kidney function. Both BUN and creatinine may be ordered when a CT scan is planned, prior to and during certain drug therapies, and before and after dialysis to monitor the effectiveness of treatments.
What does the test result mean?
Increased creatinine levels in the blood suggest kidney disease or other conditions that affect kidney function. These can include:

Damage to or swelling of blood vessels in the kidneys (glomerulonephritis) caused by, for example, infection or autoimmune diseases

Bacterial infection of the kidneys (pyelonephritis)

Death of cells in the kidneys' small tubes (acute tubular necrosis) caused by, for example, drugs or toxins

Prostate disease, kidney stone, or other causes of urinary tract obstruction

Reduced blood flow to the kidney due to shock, dehydration, congestive heart failure, atherosclerosis, or complications of diabetes

Low blood levels of creatinine are not common, but they are also not usually a cause for concern. They can be seen with conditions that result in decreased muscle mass.

Levels of 24-hour urine creatinine are evaluated with blood levels as part of a creatinine clearance test.

Single, random urine creatinine levels have no standard reference ranges. They are usually used with other tests to reference levels of other substances measured in the urine. Some examples include the urine albumin test and urine albumin/creatinine ratio and the urine protein test.
Is there anything else I should know?

Creatinine blood levels can also increase temporarily as a result of muscle injury and are generally slightly lower during pregnancy.

Some drugs may cause increased creatinine levels. Inform your healthcare provider of any drugs you are taking.
Will exercise affect my creatinine levels?

In general, moderate exercise will not affect your creatinine levels. As you continue to exercise and build muscle mass, your creatinine levels may increase slightly but not to abnormal levels.
How does diet affect creatinine levels?

Some studies have shown that eating cooked meat prior to testing can temporarily increase the level of creatinine. Creatinine levels may be 10%-30% higher in people who eat a diet that is very high in meat.
What can I do to make my creatinine level normal?

Creatinine is a reflection of processes that are going on in your body and of kidney function. It is not generally responsive to lifestyle changes. If you have an elevated creatinine that is due to a temporary condition, such as a kidney infection, then it should normalize as the infection resolves. If it is elevated due to an underlying chronic condition that can affect kidney function, such as diabetes, then it will reflect changes in kidney function and is likely to stabilize if/when the condition is under control.
What is creatine? If I take creatine, will my creatinine levels go up?

Creatine is a compound that is made primarily in the liver and then transported to your muscles, where it is used as an energy source for muscle activity. Once in the muscle, some of the creatine is spontaneously converted to creatinine. The amount of both creatine and creatinine depend on muscle mass, so men usually have higher levels than women. Creatine is now available as a dietary supplement. If you take creatine, your creatinine levels may be higher than when you do not take the supplement. You should tell your healthcare provider about all of the dietary supplements you are taking to help in the evaluation of your lab results.
Do creatinine levels change with age?

Creatinine levels relate to both muscle mass and to kidney function. As you age, your muscle mass decreases but your kidneys tend to function less effectively. The net result is not much change in creatinine levels in the blood as you get older.
What is a BUN/Creatinine ratio?

Occasionally, a health practitioner will look at the ratio between a person's BUN and blood creatinine to help determine what is causing these concentrations to be higher than normal. The ratio of BUN to creatinine is usually between 10:1 and 20:1. An increased ratio may be due to a condition that causes a decrease in the flow of blood to the kidneys, such as congestive heart failure or dehydration. It may also be seen with increased protein, from gastrointestinal bleeding, or increased protein in the diet. The ratio may be decreased with liver disease (due to decrease in the formation of urea) and malnutrition.

See More Common Questions See Less Common Questions

Related Images

Related Content

You may be able to find your test results on your laboratory's website or patient portal. However, you are currently at Lab Tests Online. You may have been directed here by your lab's website in order to provide you with background information about the test(s) you had performed. You will need to return to your lab's website or portal, or contact your healthcare practitioner in order to obtain your test results.

Lab Tests Online is an award-winning patient education website offering information on laboratory tests. The content on the site, which has been reviewed by laboratory scientists and other medical professionals, provides general explanations of what results might mean for each test listed on the site, such as what a high or low value might suggest to your healthcare practitioner about your health or medical condition.

The reference ranges for your tests can be found on your laboratory report. They are typically found to the right of your results.

If you do not have your lab report, consult your healthcare provider or the laboratory that performed the test(s) to obtain the reference range.

Laboratory test results are not meaningful by themselves. Their meaning comes from comparison to reference ranges. Reference ranges are the values expected for a healthy person. They are sometimes called "normal" values. By comparing your test results with reference values, you and your healthcare provider can see if any of your test results fall outside the range of expected values. Values that are outside expected ranges can provide clues to help identify possible conditions or diseases.

While accuracy of laboratory testing has significantly evolved over the past few decades, some lab-to-lab variability can occur due to differences in testing equipment, chemical reagents, and techniques. This is a reason why so few reference ranges are provided on this site. It is important to know that you must use the range supplied by the laboratory that performed your test to evaluate whether your results are "within normal limits."

For more information, please read the article Reference Ranges and What They Mean.

Blood Creatinine Reference Range

The reference ranges¹ provided here represent a theoretical guideline that should not be used to interpret your test results. Some variation is likely between these numbers and the reference range reported by the lab that ran your test. Please consult your healthcare provider.

AGE/GENDER	CONVENTIONAL UNITS²	SI UNITS³
0-18 years	Not available due to wide variability. See child's lab report for reference range.
18-60 years
Male	0.9 - 1.3 mg/dL	80 - 115 µmol/L
Female	0.6 - 1.1 mg/dL	53 - 97 µmol/L
60-90 years
Male	0.8 - 1.3 mg/dL	71 - 115 µmol/L
Female	0.6 - 1.2 mg/dL	53 - 106 µmol/L

¹ from Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. Burtis CA, Ashwood ER, Bruns DE, eds. 5th edition, St. Louis: Elsevier Saunders; 2011.

² Conventional Units are typically used for reporting results in U.S. labs

³ SI Units are used to report lab results outside of the U.S.

View Sources

Sources Used in Current Review

Horowitz, G. (2014 December 10, Updated). Creatinine. Medscape Drugs & Diseases [On-line information]. Available online at http://emedicine.medscape.com/article/2054342-overview through http://emedicine.medscape.com. Accessed 07/18/15.

Delgado, J. and Straseski, J. (2015 May). Renal Function Markers - Kidney Disease. ARUP Consult [On-line information]. Available online at http://www.arupconsult.com/Topics/RenalFunctionMarkers.html through http://www.arupconsult.com. Accessed 07/18/15.

Salazar, J. (2014). Overview of Urea and Creatinine. Medscape Multispecialty from Lab Med. 2014;45(1):e19-e20. [On-line information]. Available online at http://www.medscape.com/viewarticle/823420 through http://www.medscape.com. Accessed 07/18/15.

Dugdale, D. (2013 August 4, Updated). Creatinine blood test. MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/003475.htm through http://www.nlm.nih.gov. Accessed 07/18/15.

Dugdale, D. (2013 August 25, Updated). Creatinine - urine. MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/003610.htm through http://www.nlm.nih.gov. Accessed 07/18/15.

Nair S, et al. Effect of a cooked meat meal on serum creatinine and estimated glomerular filtration rate in diabetes-related kidney disease. Published online before print September 23, 2013, doi: 10.2337/dc13-1770 Diabetes Care. Available online at http://care.diabetesjournals.org/content/early/2013/09/16/dc13-1770.full.pdf+html through http://care.diabetesjournals.org. Accessed August 2013.

Sources Used in Previous Reviews

Thomas, Clayton L., Editor (1997). Taber's Cyclopedic Medical Dictionary. F.A. Davis Company, Philadelphia, PA [18th Edition].

Pagana, Kathleen D. & Pagana, Timothy J. (2001). Mosby's Diagnostic and Laboratory Test Reference 5th Edition: Mosby, Inc., Saint Louis, MO.

(2002 March). Medical Tests of Kidney Function. National Kidney and Urologic Diseases Information Clearinghouse, NIH Publication No. 02–4623 [On-line information]. Available online at http://kidney.niddk.nih.gov/kudiseases/pubs/kidneytests/index.htm through http://kidney.niddk.nih.gov.

Esson, M. and Schrier, R. (2002). Diagnosis and Treatment of Acute Tubular Necrosis. Ann Intern Med 2002;137:744-752 [On-line journal]. PDF available for download at http://www.annals.org/cgi/reprint/137/9/744.pdf through http://www.annals.org.

Agha, Irfan (2004 February 11, Updated). Creatinine – serum. MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/003475.htm.

Agha, Irfan (2004 February 11, Updated). Creatinine – urine. MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/003610.htm.

Agha, Irfan (2004 February 11, Updated). Creatinine clearance. MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/003611.htm.

Agha, Irfan (2003 August 7, Updated). BUN. MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/003474.htm.

Agrawal, M. and Swartz, R. (2000 April 1). Acute Renal Failure. American Family Physician [On-line journal]. Available online at http://www.aafp.org/afp/20000401/2077.html through http://www.aafp.org.

Nissl, J. (2004 September 20, Updated). Creatinine and Creatinine Clearance WebMD [On-line information]. Available online at http://my.webmd.com/hw/kidney_failure/hw4322.asp through http://my.webmd.com.

Physician's Reference Laboratory: Kidney Function Panel. Available online at http://www.prlnet.com/Kidney.htm through http://www.prlnet.com.

(Update: 10/22/2007) MedlinePlus Medical Encyclopedia. Creatinine, Serum. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/003475.htm. Accessed November 2008.

(Update: 10/22/2007) MedlinePlus Medical Encyclopedia. Creatinine, Urine. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/003610.htm. Accessed November 2008.

(Update: 9/4/2007) MedlinePlus Medical Encyclopedia. Creatinine clearance. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/003611.htm. Accessed November 2008.

Clarke, W. and Dufour, D. R., Editors (2006). Contemporary Practice in Clinical Chemistry, AACC Press, Washington, DC. Pp. 311-312.

National Kidney Foundation. Chronic Kidney Disease. Available online at http://www.kidney.org/kidneyDisease/ckd/index.cfm#whatare through http://www.kidney.org. Accessed January 2009.

Pagana K, Pagana T. Mosby's Manual of Diagnostic and Laboratory Tests. 3rd Edition, St. Louis: Mosby Elsevier; 2006 Pp. 206-209.

Horowitz, G. (Updated 2012 October 23). Creatinine. Medscape Reference [On-line information]. Available online at http://emedicine.medscape.com/article/2054342-overview through http://emedicine.medscape.com. Accessed November 2012.

Dugdale, D. (Updated 2011 August 20). Creatinine – blood. MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/003475.htm. Accessed November 2012.

(© 1995-2012). Creatinine with Estimated GFR (MDRD), Serum. Mayo Clinic Mayo Medical Laboratories [On-line information]. Available online at http://www.mayomedicallaboratories.com/test-catalog/Overview/8472 through http://www.mayomedicallaboratories.com. Accessed November 2012.

Dugdale, D. (Updated 2011 August 21). Creatinine – urine. MedlinePlus Medical Encyclopedia [On-line information]. Available online at http://www.nlm.nih.gov/medlineplus/ency/article/003610.htm. Accessed November 2012.

Arora, P. (Updated 2012 March 28). Chronic Kidney Disease. Medscape Reference [On-line information]. Available online at http://emedicine.medscape.com/article/238798-overview through http://emedicine.medscape.com. Accessed November 2012.

(Updated 2012 March 23). The Kidneys and How They Work. National Kidney and Urologic Diseases Information Clearinghouse (NKUDIC) [On-line information]. Available online at http://kidney.niddk.nih.gov/kudiseases/pubs/yourkidneys/ through http://kidney.niddk.nih.gov. Accessed November 2012.

Ask a Laboratory Scientist

This form enables you to ask specific questions about lab tests. Your questions will be answered by a laboratory scientist as part of a voluntary service provided by one of our partners, American Society for Clinical Laboratory Science. Please allow 2-3 business days for an email response from one of the volunteers.

Please indicate whether you are a

Country

I have read and agree to the Privacy Policy (read the Privacy Policy)

I have read and agree to the Terms of Use (read the Terms of Use)

I agree to the disclaimer (read the disclaimer).

Disclaimer

Thank you for using the Consumer Information Response Service ("the Service") to inquire about the meaning of your lab test results. The Service is provided free of charge by the American Society for Clinical Laboratory Science, which is one of many laboratory organizations that supports Lab Tests Online.
Please note that information provided through this free Service is not intended to be medical advice and should not be relied on as such. Although the laboratory provides the largest single source of objective, scientific data on patient status, it is only one part of a complex biological picture of health or disease. As professional clinical laboratory scientists, our goal is to assist you in understanding the purpose of laboratory tests and the general meaning of your laboratory results. It is important that you communicate with your physician so that together you can integrate the pertinent information, such as age, ethnicity, health history, signs and symptoms, laboratory and other procedures (radiology, endoscopy, etc.), to determine your health status. The information provided through this Service is not intended to substitute for such consultations with your physician nor specific medical advice to your health condition.
By submitting your question to this Service, you agree to waive, release, and hold harmless the American Society for Clinical Laboratory Science and its affiliates or their past or present officers, directors, employees, agents, and Service volunteers (collectively referred to as "ASCLS") and the American Association for Clinical Chemistry and its affiliates or their past or present officers, directors, employees, agents, and Service volunteers (collectively referred to as "AACC") from any legal claims, rights, or causes of action you may have in connection with the responses provided to the questions that you submit to the Service.
AACC, ASCLS and its Service volunteers disclaim any liability arising out of your use of this Service or for any adverse outcome from your use of the information provided by this Service for any reason, including but not limited to any misunderstanding or misinterpretation of the information provided through this Service.

See More See Less