what is the harm of the blood urea high level?

Generally, a high blood urea nitrogen level means your kidneys aren't working well, particularly if the result is above 50 mg/dL (17.85 mmol/L). But, elevated urea nitrogen can also be due to urinary tract obstruction, congestive heart failure or gastrointestinal bleeding. Your blood urea nitrogen level may also increase as a result of dehydration, shock, burns or fever. Certain medications, such as corticosteroids, may increase urea nitrogen levels, too. In addition, a high protein diet can cause your BUN level to increase