What it means
The liver turns the nitrogen from protein into urea, and the kidneys remove it in urine. The BUN is read together with creatininekree-AT-uh-neenA waste product of muscle that the kidneys remove from the blood; its blood level is used to measure how well the kidneys work.Full entry to look at kidney function. It rises when the kidneys are failing, and also with dehydrationdee-hy-DRAY-shunA state in which the body has lost more water than it has taken in.de- remove, lack ofhydr/o water-ation processFull entry , bleeding in the stomach or bowel, and a high-protein diet; it can fall with overhydration and liver disease.
For the nurse
Report a rising BUN, along with the creatinine, urine output and daily weight. A high BUN with a normal creatinine often points to dehydration, so check intake and output and signs of fluid loss.
At a glance
| Normal range | 7–20 mg/dL [2.5–7.1 mmol/L]; normal ranges vary by lab and age |
|---|---|
| Abbreviations | BUN |
| Spanish | nitrógeno ureico en sangre |
| Also written | BUN, urea nitrogen, serum urea |
Related terms
dehydration
A state in which the body has lost more water than it has taken in.
chronic kidney disease
Kidney damage or reduced kidney function that lasts longer than three months.
renal
Relating to the kidneys.
creatinine
A waste product of muscle that the kidneys remove from the blood; its blood level is used to measure how well the kidneys work.