Dictionary of Cancer Terms
View in Spanish: NUS
BUN
Nitrogen in the blood that comes from urea (a substance formed by the breakdown of protein in the liver). The kidneys filter urea out of the blood and into the urine. A high level of urea nitrogen in the blood may be a sign of a kidney problem. Also called blood urea nitrogen and urea nitrogen.
Source: National Cancer Institute Dictionary of Cancer Terms, available at www.cancer.gov/dictionary.