Blood Urea Nitrogen is an important indicator of kidney function. Other terms that can be used as synonyms for this term include BUN, Azotemia, Uremia, and Blood Uric Acid. BUN is often used to evaluate how well the kidneys are functioning and to monitor the progress of kidney disease. Azotemia refers to an excess of nitrogen in the blood, and Uremia is a condition in which the waste products normally excreted by the kidneys accumulate in the blood. Blood Uric Acid is a related test that measures the level of uric acid in the blood and may also be used to assess kidney function.