Which statement best describes laboratory findings consistent with chronic renal failure?

• A. Elevated BUN and creatinine levels.
• B. Normal BUN and creatinine levels.
• C. Low BUN and high creatinine.
• D. High BUN and low creatinine.

Answer: (A)

In chronic kidney disease, the kidneys lose their ability to filter waste products, so substances that are normally excreted accumulate in the blood. BUN (blood urea nitrogen) and creatinine are two waste products routinely measured to assess renal function. When filtration declines, both BUN and creatinine levels rise. Creatinine is a particularly reliable marker because its production is relatively steady and its clearance closely tracks glomerular filtration rate; BUN can be influenced by factors like protein intake and hydration, but it also tends to rise as kidney function worsens. Therefore, elevated BUN alongside elevated creatinine best reflects chronic renal failure.