Blood urea nitrogen (BUN) test

BUN is an indication of renal health. Normal ranges 8-20 mmol/L. If Glomerular Filtration Rate (GFR) and blood volume decrease (hypovolemia) then BUN will increase. Other factors responsible for its increment are fever, increasedcatabolism, high-protein diet and gastrointestinal bleeding.
BUN (urea-N) is mg/dL in the United States, Mexico, Italy, Austria, Germany. Elsewhere, the concentration of urea is reported as mmol/L, generally depending on the lab.
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)
Urea [mmol/L] = BUN [mg/dL of nitrogen] x 10 [dL/L] / 14x2 [mg N/mmol urea]
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]
Urea nitrogen levels tend to increase with age. Infants have lower levels than other people do, and the range in children varies.
Generally, a high blood urea nitrogen level means your kidneys aren't working well. But elevated urea nitrogen can also be due to:
· Urinary tract obstruction
· Congestive heart failure or recent heart attack
· Gastrointestinal bleeding
· Dehydration, resulting from not drinking enough fluids or for other reasons
· Shock
· Severe burns
· Certain medications, such as corticosteroids and some antibiotics
· A high protein diet

If kidney damage is a concern, ask your doctor what factors may be contributing to the damage and what steps you can take to try to control them.