Blood Urea Nitrogen (BUN) Test

The Blood Urea Nitrogen (BUN) test is a medical laboratory test that measures the level of urea nitrogen in the blood. Urea nitrogen is a waste product that occurs in the blood when the body breaks down protein.

Purpose of the Test

The BUN test is used to evaluate kidney function and to diagnose kidney disease or damage. It can also be used to monitor the effectiveness of treatment for kidney disease.

How the Test is Performed

A blood sample is drawn from a vein in the arm, usually using a needle and syringe. The blood sample is then sent to a laboratory for analysis.

What the Results Mean

The normal range for BUN is typically between 6 and 24 milligrams per deciliter (mg/dL). Abnormal results may indicate:

• Kidney disease or damage
• Dehydration
• Heart failure
• Shock
• High blood pressure
• Diabetes

Factors that Can Affect the Results

Certain factors can affect the results of the BUN test, including:

• Diet: A high-protein diet can increase BUN levels
• Medications: Certain medications, such as antibiotics and diuretics, can affect kidney function and BUN levels
• Pregnancy: BUN levels may be lower during pregnancy due to increased blood volume
• Aging: BUN levels may increase with age due to decreased kidney function

Limitations of the Test

The BUN test has some limitations. It can be affected by factors other than kidney disease, and it may not detect early stages of kidney disease. Other tests, such as the creatinine test, may be used in conjunction with the BUN test to evaluate kidney function.