BUN (Blood Urea Nitrogen)

Definition: BUN (blood urea nitrogen) is a marker of kidney function, that doctors use to determine the progression of kidney failure. Kidney failure is a complication of diabetes. One of the tests used to assess kidney function is a simple blood test that shows the BUN (blood urea nitrogen) level in the blood. BUN is a waste product of cell metabolism. When blood flows through the body, protein circulates to cells. Cells use the protein and excrete the waste that they don't need. This waste is called urea. Urea also contains nitrogen. Normally urea is filtered out of the blood by the kidneys. If the kidneys are damaged and not functioning properly, urea and nitrogen are not filtered fully from the blood. A BUN of over 20 mg/dl is an indicator of decreased kidney function.