what is urea nitrogen

Urea nitrogen is a waste product that forms in the liver when it breaks down proteins used by the bodys cells. The nitrogen combines with other elements to form urea, which is a chemical waste product that travels from the liver to the kidneys through the bloodstream. Healthy kidneys filter urea and remove other waste products from the blood. A blood urea nitrogen (BUN) test measures the amount of urea nitrogen in the blood, which is an important marker for kidney function. The test is commonly used to reveal important information about how well the kidneys are working. Normal ranges for BUN levels may vary depending on the reference range used by the lab and the age of the person. Generally, a high BUN level means the kidneys are not filtering urea properly, which may indicate a condition affecting the kidneys health.