Urea is formed by the liver as the finale by-product of protein catabolism and is [hopefully] excreted out via urine. BUN is a reflection of the ratio between the production and excretion of urea. BUN is a test that is used (preferably alongside a serum creatinine test) to evaluate kidney function.
Standard procedure guidelines require the patient to restrict consumption of protein-rich foods 24 hours prior to the test.
For maximal accuracy, combine this test with:
- Serum creatinine test.
- Blood pressure checkup on both arms.
If BUN is substantially elevated, consider decline in kidney function hence inability to also filter sediment.