/ Mayo Medical Laboratories. ScienceDirect ® is a registered trademark of Elsevier B.V. ScienceDirect ® is a registered trademark of Elsevier B.V. URL: https://www.sciencedirect.com/science/article/pii/B9780128012383000222, URL: https://www.sciencedirect.com/science/article/pii/B9780123704696000039, URL: https://www.sciencedirect.com/science/article/pii/B9780123302151500077, URL: https://www.sciencedirect.com/science/article/pii/B9780124692350500130, URL: https://www.sciencedirect.com/science/article/pii/B9781455746170000339, URL: https://www.sciencedirect.com/science/article/pii/B9780323478717000125, URL: https://www.sciencedirect.com/science/article/pii/B9780323449427001448, URL: https://www.sciencedirect.com/science/article/pii/B9780124157590000182, URL: https://www.sciencedirect.com/science/article/pii/B9780128030141000066, URL: https://www.sciencedirect.com/science/article/pii/B9780123963505500140, Biomarkers of Kidney Disease (Second Edition), 2017, Wanda M. Haschek, ... Matthew A. Wallig, in, Fundamentals of Toxicologic Pathology (Second Edition), Handbook of Toxicologic Pathology (Second Edition), Ronald M. McLaughlin, Richard E. Fish, in, The Biology of the Laboratory Rabbit (Second Edition), Clinical Approach to the Diagnosis of Acute Kidney Injury, National Kidney Foundation Primer on Kidney Diseases (Sixth Edition), Measurement of glomerular filtration rate, Starting and Stopping Renal Replacement Therapy in the Critically Ill, Rakesh Malhotra, ... Ravindra L. Mehta, in, Haschek and Rousseaux's Handbook of Toxicologic Pathology (Third Edition), Biomarkers of Kidney Disease (Second Edition), Clinical Biochemistry of Domestic Animals (Third Edition), Biochemical and Biophysical Research Communications. L
N In general, around 7 to 20 mg/dL (2.5 to 7.1 mmol/L) is considered normal. The blood sample is sent to a lab for analysis. 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. Like BUN, high levels of creatinine could mean there is a lot of waste product that hasn’t been removed by the kidneys. Your doctor will give you specific instructions. BUN and creatinine are the primary tests used to check how well the kidneys are able to filter waste products from your blood. High catabolic states and high protein diets are associated with greater urea nitrogen production, and rises in daily BUN concentration that can exceed 50 mg/dl. Decreased BUN may be seen in severe liver disease, malnutrition, and sometimes when you are overhydrated (too much fluid volume), but the BUN test is not usually used to diagnose or monitor these conditions. Available from: National Kidney Disease Education Program: Laboratory Evaluation [Internet]. Values that are outside expected ranges can provide clues to help identify possible conditions or diseases. Urea nitrogen is one of the waste products removed from your blood by your kidneys. The Kidneys and How They Work. This usually takes less than five minutes. It may feel a little bit sore afterward, but you can go straight back to your everyday activities. The same statements are valid for comparison of comparable BUN values and emphasize that measurement of serum levels alone is not a precise method of assessing existing renal function. This is because the BUN level by itself doesn’t always reveal much. If one kidney is fully functional, the BUN level may be normal even when the other kidney is not functioning properly. / On a practical basis, these findings indicate that a patient with SC of 3 mg/dl probably has many more than twice as many functional nephrons as a patient with SC of 6 mg/dl. http://www.uptodate.com/home. Thomas, Clayton L., Editor (1997). In the event of a medical emergency, call 911 immediately.

U m Blood Urea Nitrogen (BUN) Test: Overview; 2016 Jul 2 [cited 2017 Jan 30]; [about 3 screens]. American Family Physician [On-line journal]. WebMD does not provide medical advice, diagnosis or treatment. Because ruminant microflora may metabolize a greater percentage of urea than do enteric flora in nonruminants, BUN values may not increase proportionately to SC levels in renal failure in these species until anorexia occurs. ∗ They are sometimes called "normal" values. Medscape Reference [On-line information]. Available from: Mayo Clinic [Internet]. Accessed 07/18/15. The nitrogen combines with other elements, such as carbon, hydrogen and oxygen, to form urea, which is a chemical waste product. 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.
Thank you for using the Consumer Information Response Service ("the Service") to inquire about the meaning of your lab test results. In contrast, a randomized controlled trial conducted in oliguric critically ill patients in Europe revealed no significant difference in hospital mortality with early (mean BUN, 46 mg/dL) versus late (105 mg/dL) initiation of hemofiltration.15 These findings have been disputed because they did not account for nonrenal dependent processes that influence BUN. 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. ∗

Most diseases or conditions that affect the kidneys or liver have the potential to affect the amount of urea present in the blood. Urea synthesis occurs in hepatocytes via the urea cycle, which is one method of incorporating NH4+ into molecules for excretion of excess NH4+ that is formed in tissues or intestines. Volume depletion, hyperalimentation, gastrointestinal bleeding, and exogenous glucocorticoids raise BUN and are seen commonly in AKI patients in critical care settings. = Creatinine enters plasma after degradation of creatine or creatine phosphate in muscle fibers. High levels can also indicate the following: ● Urinary tract obstruction (blockage from being able to pee), ● Congestive heart failure (when your heart doesn’t pump blood to your body like it should), ● Gastrointestinal bleeding (bleeding in your digestive tracts, such as your stomach, intestines, or esophagus). Talk to your doctor about what could be causing the problem and plan your next steps. (© 2011). e National Kidney and Urologic Diseases Information Clearinghouse, NIH Publication No. If kidney problems are the main concern, the creatinine levels in your blood will likely also be measured when your blood is tested for urea nitrogen levels. Smith, ... R.M. If any of them might alter the test result, your doctor may ask you to stop taking them for a period of time. Of the 39 variables evaluated in this analysis, BUN ≥ 43 mg dl−1 was the single best predictor of mortality, followed by admission systolic blood pressure <115 mm Hg and serum creatinine ≥ 2.75 mg dl−1 (Fonarow et al., 2005). Accessed November 2008. Their meaning comes from comparison to reference ranges. B Burtis CA, Ashwood ER, Bruns DE, eds. 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 if not cleared rapidly. The liver produces urea in the urea cycle as a waste product of the digestion of protein. Accessed November 2012. The ideal ratio of BUN to creatinine falls between 10-to-1 and 20-to-1. 3rd Edition, St. Louis: Mosby Elsevier; 2006 Pp. It is not considered as reliable as creatinine or BUN/creatinine ratio blood studies. You may have slight pain or bruising at the spot where the needle was put in, but most symptoms go away quickly. L Urea is formed in and released by the liver into the blood and is carried to the kidneys, where it is filtered out of the blood and released into the urine. However, you are currently at Lab Tests Online. / Pagana, K. D. & Pagana, T. J.

Protein metabolism produces ammonia, which is eventually converted to the less toxic waste product, urea. Notice that values for blood urea nitrogen and serum creatinine concentrations do not exceed the normal range until renal dysfunction is marked. Lab Tests Online. Abnormally high BUN and SC values were found in patients with normal renal function in 9 and 4% of the patients, respectively (Rickers et al., 1978). If you have a kidney condition, the test is a way to check what your BUN levels are before you start a medication or treatment. Urine IL-18, urine NGAL, and urine KIM-1 are biomarkers of poor prognosis in patients with AKI. UrologyHealth.org, Kidney (renal) Failure. 1 from Tietz Textbook of Clinical Chemistry and Molecular Diagnostics. Not available due to wide variability.