what causes elevated urea
Blood Urea Nitrogen  (BUN) An elevated BUN may be caused by: 1  Impaired renal function. 2  Congestive heart failure as a result of poor renal perfusion. 3  Dehydration. Shock.  Hemorrhage into the gastrointestinal 1  tract. Acute myocardial infarction. 2  Stress. Excessive protein intake or protein catabolism. Overview Ask your doctor to explain your results. Urea nitrogen levels tend to increase with age. Infants have lower levels than other people do, and the range in children varies. Generally, a high blood urea nitrogen level means your kidneys aren't working well. But elevated blood urea nitrogen can also be due to: 1  Urinary tract obstruction. 2  Congestive heart failure or recent heart attack. 3  Gastrointestinal bleeding.  Dehydration, resulting from not drinking enough fluids or for other 1  reasons. Shock.  Severe 1  burns. Certain medications, such as some antibiotics.  A high-protein diet.