Normal Reference Ranges
Adult
7 - 20 mg/dL
Pediatric
5 - 18 mg/dL
Clinical Significance
End product of protein metabolism. BUN/Cr ratio > 20:1 suggests prerenal etiology (e.g., dehydration, GI bleed).
Causes of High
- Renal failure
- Dehydration (Prerenal azotemia)
- GI Bleeding
- High protein diet
- Heart failure
Causes of Low
- Severe liver damage
- Malnutrition
- Overhydration