All Tests Category Search
'Liver Diseases' 

The blood urea nitrogen (BUN) test is a test of how well your kidneys are working. It measures the amount of nitrogen in your blood. The nitrogen is present in a chemical called urea. Urea is a waste product produced as your body digests protein. Urea is carried by the blood to the kidneys, which filter the urea out of the blood and into the urine.
Urea is the principle waste product of protein catabolism. BUN is most commonly measured in the diagnosis and treatment of certain renal and metabolic diseases. Increased BUN concentration may result from increased production of urea due to (1) diet or excessive destruction of cellular proteins as occurs in massive infection and fevers, (2) reduced renal perfusion resulting from dehydration or heart failure, (3) nearly all types of kidney disease, and (4) mechanical obstruction to urine excretion such as is caused by stones, tumors, infection, or stricture. Decreased urea levels are less frequent and occur primarily in advanced liver disease and in overhydration.

A significant deviation from the normal range may require further evaluation by your physician.