Final answer:
An elderly patient with renal insufficiency would likely have decreased GFR and elevated serum creatinine levels due to impaired kidney function, rather than increased GFR, normal serum creatinine, increased drug excretion, or hypokalemia.
Step-by-step explanation:
The question concerns an elderly patient with renal insufficiency and their expected laboratory findings. Given that renal insufficiency is commonly associated with a decrease in the glomerular filtration rate (GFR), we can rule out an increased GFR as an expected finding. A normal serum creatinine level is unlikely because serum creatinine is typically elevated when the kidneys are not functioning properly. An increased ability to excrete drugs is not anticipated because a decline in renal function usually leads to a reduced ability to excrete drugs due to decreased GFR. Lastly, hypokalemia is not typical in renal failure; instead, hyperkalemia may occur due to decreased excretion of potassium.
Hence, the most accurate answer would be increased serum creatinine, indicating a decrease in the kidney's excretory function and GFR. While a complete answer to the given options isn't provided in the question itself, based on our knowledge of renal insufficiency, we anticipate altered laboratory findings reflective of impaired kidney function.