The kidneys are two bean-shaped organs located on each side of the spine. They’re responsible for filtering out of the blood waste products, excess water, and other impurities. These important organs also control the pH, salt levels, and potassium levels in the body. The kidneys even produce hormones that manage red blood cell production and regulate blood pressure.

A blood urea nitrogen (BUN) test is used to determine how well your kidneys are working. It does this by measuring the amount of urea nitrogen in the blood. Urea nitrogen is a waste product that’s created in the liver when the body breaks down proteins. Normally, the kidneys filter out this waste, and urinating removes it from the body.