Q. A 48-year-old man with a family history of kidney disease comes to the physician’s clinic for a routine check-up. He has been feeling some flank pain for the past six months and notices that he has been urinating more frequently, especially at night. He has no other medical conditions and is not on any medications. On physical examination, his blood pressure is 140/90 mm Hg, and there are palpable bilateral abdominal masses. A subsequent renal ultrasound shows multiple bilateral renal cysts. Laboratory results reveal a serum creatinine level of 1.5 mg/dL and a GFR of 50 mL/min/1.73 m². What is the most appropriate next step in the management of this patient?