Understanding Blood Urea Nitrogen (BUN): Causes & Significance

Blood urea nitrogen (BUN) represents the amount of nitrogen present in the form of urea in the bloodstream. Urea is the main nitrogenous waste product of protein metabolism in the liver. The kidneys filter urea from the blood and excrete it in the urine. BUN levels can be used to assess kidney function.

Increased BUN levels may indicate:

- Kidney damage or disease

- Dehydration

- High-protein diet

- Pregnancy

- Certain medications such as diuretics and corticosteroids

Decreased BUN levels may indicate:

- Liver damage or disease

- Low-protein diet

- Malnutrition

- Overhydration

- Certain medications such as antibiotics