Final answer:
A. Increased GFR, decreased serum creatinine, increased urea nitrogen
In summary, a healthy increase in GFR should lead to decreased serum creatinine levels, signifying better clearance, but urea nitrogen levels can vary.
Step-by-step explanation:
When assessing the impact on the glomerular filtration rate (GFR), serum creatinine, and urea nitrogen levels, typically, changes in these parameters signify the functional status of the kidneys. An increase in GFR would generally correspond to an increase in the kidneys' filtration capacity, often resulting in decreased serum creatinine levels since more of this waste product is being effectively cleared from the blood. Conversely, an increase in urea nitrogen levels can occur in a variety of conditions that affect the kidneys or the body's ability to excrete urea, such as dehydration or kidney dysfunction.
Given this understanding, if the GFR increases, serum creatinine would tend to decrease, but urea nitrogen could either stay the same or increase, depending on the underlying condition. However, option A from the presented choices, which includes an increased GFR, a decreased serum creatinine, and an increased urea nitrogen, aligns most closely with the recognized physiological responses to a healthy increase in kidney filtration function. It's important to note that in situations where there is kidney damage leading to renal uremia, increased blood urea levels can indeed be observed, and this would typically correlate with a decreased GFR.