Renal function decreases at age 50 by what percent?

• A. 25%
• B. 50%
• C. 5%
• D. 10%

Answer: (A)

Aging reduces renal function because the kidneys lose nephrons and the glomerular filtration rate declines over time. By about age 50, many resources summarize the decline as roughly a 25% reduction in overall renal function compared with young adults. This means drug clearance, especially for renally excreted medications, can be slower, so dosing often needs adjustment based on renal function (e.g., using eGFR or creatinine clearance).

This 25% figure is a commonly used approximate rule in pharmacology to illustrate how aging affects drug handling in the kidneys. Individual variation is common, and some people may show less or more decline, but 25% by age 50 is the typical teaching point. The other options describe too small or too large a change for most people by that age, which is why 25% is the best representative estimate in this context.