Blood Urea Nitrogen (BUN)

 Urea nitrogen is the nitrogen portion of urea, a substance formed in the liver through an enzymatic protein breakdown process. Urea is normally freely filtered through the renal glomeruli, with a small amount reabsorbed in the tubules and the remainder excreted in the urine. Elevated levels indicate a slowing of the glomerular filtration rate.

Normal Lab Value for Blood Urea Nitrogen

  • 8 to 25 mg/dL

Nursing consideration

  • BUN and creatinine ratios should be analyzed when renal function is evaluated.