Urea nitrogen is produced in the liver during protein breakdown and excreted by the kidneys.

The BUN test provides a quick measure of how well the kidneys are filtering waste.

Clinical uses include:

Diagnosing acute or chronic kidney disease.

Monitoring patients with dehydration, heart failure, or liver disease.

Evaluating protein metabolism and nutritional status.

Interpreting results alongside serum creatinine for a more complete renal assessment.

The test is performed using a blood sample.

Analyte: Blood urea nitrogen concentration.

Normal Range: ~7 – 20 mg/dL (varies slightly by lab).

Abnormal Findings:

High BUN: Suggests kidney dysfunction, dehydration, high protein intake, gastrointestinal bleeding, or heart failure.

Low BUN: May indicate liver disease, malnutrition, or overhydration.

Clinical Use:

Provides insight into kidney’s ability to excrete nitrogen waste.

Helps differentiate renal vs. non-renal causes of abnormal urea levels.

Guides treatment and monitoring in renal and metabolic disorders.