The BUN (Blood Urea Nitrogen) test measures the amount of urea nitrogen in the blood. Urea is a waste product formed from the breakdown of proteins in the liver and is excreted by the kidneys. This test is primarily used to assess kidney function and to diagnose or monitor kidney disease and the effectiveness of its treatment.
A normal BUN level typically ranges from 7 to 20 mg/dL, but it may vary depending on age, diet (especially high protein intake), hydration status, or the use of certain medications (such as corticosteroids).
An elevated BUN may indicate kidney failure, dehydration, urinary tract obstruction, or increased protein breakdown (e.g., due to gastrointestinal bleeding), whereas a low BUN level may result from severe liver damage, malnutrition, or insufficient protein intake.
BUN is often measured along with creatinine and the BUN/creatinine ratio to help determine the underlying causes of kidney dysfunction. The test results should always be interpreted in the context of clinical symptoms and other laboratory findings, as it cannot alone provide a definitive diagnosis.
