Description
A Blood Urea Nitrogen (BUN) test measures the amount of nitrogen in your blood, and is used to provide doctors with information on how well your kidneys and liver are functioning. 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. The nitrogen comes from the waste product urea, which is converted from nitrogen and produced in the liver when protein is metabolized after eating.
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.
Healthy kidneys then filter the urea and remove other waste products like urea through urination. It is normal to have some urea present in the blood since your liver is always producing it, but too much may indicate an issue with your kidneys.
