Blood urea nitrogen; BUN
To evaluate kidney function and monitor the effectiveness of dialysis
If you have non-specific symptoms that may indicate a kidney problem
A blood sample drawn from a vein in the arm
Urea is produced when protein is broken down by the body. Healthy kidneys eliminate more than 90% of the urea the body produces, so blood levels indicate how well your kidneys are working.
A blood sample is drawn from a vein in the arm.
No test preparation is needed.
Urea and creatinine levels are used to evaluate kidney function and to monitor patients with kidney failure or those receiving dialysis.
Urea may be used in a panel of tests:
Urea is often ordered with creatinine:
High urea levels suggest impaired kidney function. This may be due to acute or chronic kidney disease. However, there are many things besides kidney disease that can affect urea levels such as decreased blood flow to the kidneys as in congestive heart failure, shock, stress, recent heart attack or severe burns; bleeding from the gastrointestinal tract; conditions that cause obstruction of urine flow; or dehydration.
Low urea levels are not common and are not usually a cause for concern. They can be seen in severe liver disease or malnutrition but are not used to diagnose or monitor these conditions. Low urea is also seen in normal pregnancy.
Urea levels increase with age and also with the amount of protein in your diet. High-protein diets may cause abnormally high urea levels. Very low-protein diets can cause abnormally low urea. Lower urea levels are also seen in infants and small children.
Drugs that impair kidney function may increase urea levels. Your urea and creatinine may be monitored if you are on certain drugs.
Tests: Creatinine, electrolytes
Conditions: Kidney disease
RCPA Manual: urea
Kidney Health Australia
Last Review Date: June 6, 2013