Urea / BUN (Blood Urea Nitrogen)
Definition
Measures the amount of urea nitrogen in the blood. Urea nitrogen is a waste product formed when the body breaks down proteins, and it is normally removed by the kidneys through urine.
Purpose
Screens for kidney function impairment in routine checkups. Monitors treatment for kidney disease. Detects early kidney problems in at-risk individuals (diabetes, hypertension, family history, obesity, smoking history, age over 60).
Results
- High BUN, decline in kidney function, dehydration, burns, a recent heart attack, a high-protein diet, or certain medications
- Low BUN, insufficient protein intake, malnutrition, or liver disease
Normal Values
Laboratory-specific. Levels generally increase with age and vary by sex.
Risks and Limitations
BUN alone is not sufficient to diagnose kidney disease, an abnormal result does not always indicate a condition requiring treatment. Age, sex, nutrition, fluid status, and medication use affect the level.