Blood urea nitrogen - wikipedia Blood urea nitrogen `` BUN '' redirects here. For other uses, see Bun ( disambiguation ). Blood urea nitrogen Medical diagnostics Urea MeSH D001806 LOINC 6299 - 2, 59570 - 2, 12961 - 9, 12963 - 5, 12962 - 7 ( edit on Wikidata ) Blood urea nitrogen ( BUN ) is a medical test that measures the amount of urea nitrogen found in blood. The liver produces urea in the urea cycle as a waste product of the digestion of protein. Normal human adult blood should contain between 6 and 20 mg of urea nitrogen per 100 ml ( 6 -- 20 mg / dL ) of blood. Individual laboratories will have different reference ranges as the assay used will vary between laboratories. Contents 1 Interpretation 2 Units 3 See also 4 References 5 External links Interpretation Blood urea nitrogen ( BUN ) is an indication of renal ( kidney ) health. The normal range is 1.8 - 7.1 mmol / L or 6 -- 20 mg / dL. Blood urea nitrogen levels can also help identify damage to body systems and diseases of the digestive, circulatory and respiratory systems. The main causes of an increase in BUN are : high protein diet, decrease in glomerular filtration rate ( GFR ) ( suggestive of renal failure ) and in blood volume ( hypovolemia ), congestive heart failure, gastrointestinal hemorrhage, fever and increased catabolism. Hypothyroidism can cause both decreased GFR and hypovolemia, however BUN - to - creatinine ratio has been found to be lowered in hypothyroidism and raised in hyperthyroidism. The main causes of a decrease in BUN are severe liver disease, anabolic state, and syndrome of inappropriate antidiuretic hormone. Reference ranges for blood tests, comparing urea ( yellow at right ) to other blood constituents. Another rare cause of a decreased BUN is ornithine transcarbamylase deficiency, which is a genetic disorder inherited in an X-linked recessive pattern. OTC Deficiency is also accompanied by hyperammonemia and high orotic acid levels. Units BUN ( urea - N ) is mg / dL in the United States, Mexico, Italy, Austria, and Germany. Elsewhere, the concentration of urea is reported as mmol / L, generally depending on the lab. BUN ( urea - N ) SI unit is mmol / L BUN ( mmol / L ) = BUN ( mg / dL ) * 0.3571 To convert from mg / dL of blood urea nitrogen to mmol / L of urea, multiply by 0.357 ( each molecule of urea having 2 nitrogens, each of molar mass 14g / mol ) ( BUN is the mass of nitrogen within urea / volume, not the mass of urea ) Urea ( mmol / L ) = BUN ( mg / dL of nitrogen ) x 10 ( dL / L ) / 14x2 ( mg N / mmol urea ) ( the mass of nitrogen within urea is used ) convert BUN to urea in mg / dL by using following formula : Urea ( mg / dL ) = BUN ( mg / dL ) * 2.14 ( conversion factor derived by : MW of urea = 60, MW of urea nitrogen = 14x2 = > 60 / 28 = 2.14 ) factor = 1 for conversions in mmol ( 1 mole N2 = 2 moles N per mole of urea ) : BUN ( mmol / L ) = urea ( mmol / L ) See also BUN - to - creatinine ratio Kt / V Urea reduction ratio ( URR ) Urine urea nitrogen Standardized Kt / V References Jump up ^ Last page of Deepak A. Rao ; Le, Tao ; Bhushan, Vikas ( 2007 ). First Aid for the USMLE Step 1 2008 ( First Aid for the Usmle Step 1 ). McGraw - Hill Medical. ISBN 0 - 07 - 149868 - 0. Jump up ^ Normal Lab Results Archived December 16, 2014, at the Wayback Machine. from Marshal University School of Medicine Jump up ^ `` Blood Urea Nitrogen ''. biologydictionary.net. Retrieved 11 July 2017. ^ Jump up to : Longo et al., Harrison 's Principles of Internal Medicine, 18th ed., p. 611 External links Reference ranges for blood tests ( CPT 82000 -- 84999 ) Electrolytes Sodium Potassium Chloride Calcium Renal function Creatinine Urea BUN - to - creatinine ratio Plasma osmolality Serum osmolal gap Acid - base Anion gap Arterial blood gas Base excess Bicarbonate CO content Iron tests Ferritin Serum iron Transferrin saturation Total iron - binding capacity Transferrin Transferrin receptor Hormones ACTH stimulation test Thyroid function tests Thyroid - stimulating hormone Metabolism Blood lipids Cardiovascular Cardiac marker Troponin test CPK - MB test Lactate dehydrogenase Myoglobin Glycogen phosphorylase isoenzyme BB Liver function tests Proteins Human serum albumin Serum total protein ALP transaminases ALT AST AST / ALT ratio Bilirubin Unconjugated Conjugated Pancreas Amylase Lipase Pancreatic lipase Retrieved from `` https://en.wikipedia.org/w/index.php?title=Blood_urea_nitrogen&oldid=797423437 '' Categories : Chemical pathology Nitrogen cycle Nephrology Hidden categories : Webarchive template wayback links Talk Contents About Wikipedia Deutsch Español فارسی Italiano עברית 日本 語 Polski Português Scots தமிழ் 中文 Edit links This page was last edited on 26 August 2017, at 23 : 54. About Wikipedia

Question: what is the normal range for urea nitrogen
Answer: between 6 and 20 mg of urea nitrogen per 100 ml (6–20 mg/dL) of blood