Final answer:
The BUN/Creatinine ratio typically increases in acute renal failure due to the enhanced reabsorption of urea relative to creatinine as kidney function is compromised. This ratio serves as an indicator of renal function, reflecting the kidneys' ability to filter waste products from the blood. Conditions like dehydration can exacerbate this increase in the ratio.
Step-by-step explanation:
In acute renal failure (ARF), the ratio of blood urea nitrogen (BUN) to creatinine typically increases. This change occurs because urea is reabsorbed by the kidneys to a greater extent than creatinine, and when renal function is compromised, as in ARF, this reabsorption of urea relative to creatinine is enhanced. Consequently, the BUN/creatinine ratio rises. Acute renal failure is characterized by a sudden decline in kidney function, leading to a failure to effectively filter waste products from the blood, and may be due to various causes such as hypoperfusion, nephrotoxic injury, or urinary tract obstruction.
As BUN and creatinine are both waste products normally filtered by the kidneys, their levels in the blood are useful indicators of renal function. In ARF, the impaired kidney function leads to a reduced clearance of both substances. However, the rate of this reduction differs between the two, resulting in an increased BUN/creatinine ratio. Conditions such as dehydration can further exacerbate this increase in the ratio by causing a pre-renal state where there is less fluid for the kidneys to filter, more concentrated blood, and thus higher reabsorption of BUN.