Which of the following clinical findings among older adults is most likely to be viewed as a normal part of aging?

A. 60–89 mL/min/1.73m²: This range indicates mildly decreased GFR, often classified as Stage 2 chronic kidney disease. Renal function is still relatively preserved and not considered renal failure at this stage.

B. 30–59 mL/min/1.73m²: This reflects a moderate decrease in GFR, typically Stage 3 CKD. Although kidney function is significantly impaired, it is not yet categorized as renal failure.

C. 15–29 mL/min/1.73m²: This GFR indicates severe kidney impairment and is classified as Stage 4 CKD. While this stage shows significant dysfunction, renal failure is generally diagnosed at lower values.

D. <15 mL/min/1.73m²: A GFR below 15 signals end-stage renal disease (ESRD), also referred to as renal failure. At this stage, dialysis or kidney transplantation is usually necessary to sustain life.

A. Atrophy of the remaining kidney: In cases of unilateral kidney loss, the remaining kidney typically does not atrophy but instead adapts to compensate for the lost function. Atrophy would be unlikely unless there is an underlying disease affecting the remaining kidney.

B. Compensatory hypertrophy of the remaining kidney: When one kidney is removed or nonfunctional, the remaining kidney often undergoes compensatory hypertrophy, increasing in size and function to handle the body's metabolic needs. This process helps maintain adequate renal function despite loss of one kidney.

C. Renal failure: While loss of one kidney reduces overall renal mass, a healthy remaining kidney usually compensates sufficiently to prevent renal failure. Renal failure is unlikely unless the remaining kidney has preexisting damage or disease.

D. Dysplasia in the remaining kidney: Dysplasia refers to abnormal development or growth of tissue, typically congenital. It is not an expected response to removal of the opposite kidney. The remaining kidney usually develops normally unless affected by a congenital abnormality.