American Board of Surgery Qualifying Exam (ABS QE) Practice Test

Which of the following best describes the effect of aging on renal function?

1. Stable glomerular filtration rate

2. Decreased renal mass over time

3. Increased fluid retention capability

4. Improved sodium conservation by the kidneys

The correct answer is: Decreased renal mass over time

As individuals age, there is a progressive decline in renal mass, which directly impacts kidney function. This reduction in renal mass can lead to decreased nephron numbers and overall kidney functionality. Importantly, these changes contribute to a gradual decline in glomerular filtration rate (GFR), which is a critical measure of kidney performance. While some aspects of renal function remain relatively stable in elderly individuals, such as the ability to excrete certain waste products, the overall trend is toward diminished renal mass. This decreased mass affects the kidneys' ability to filter blood and manage fluid and electrolytes effectively, ultimately leading to a potential increase in the risk of conditions like chronic kidney disease. In contrast, options like stable glomerular filtration rate and improved sodium conservation do not accurately reflect the typical changes seen with aging, as these parameters often decrease or decline in efficacy with age. Additionally, the body’s ability to retain fluid may not increase with age; rather, fluid balance can become disrupted, making option three less applicable. As such, the best description of the effect of aging on renal function is the decrease in renal mass over time.