According to CMS, ESRD occurs from the destruction of normal kidney tissues over a long period of time. Often, there are no symptoms until the kidney has lost more than _____________ of its function and is usually irreversible and permanent.

• A. -25%
• B. -50%
• C. -75%
• D. -100%

Answer: (B)

The kidneys have a large reserve capacity, so symptoms often don’t appear until a substantial portion of function is lost. When more than half of kidney function is gone, the remaining nephrons can no longer compensate effectively, and the damage tends to be irreversible. This is the point where the condition progresses toward end-stage renal disease, which is typically defined by the need for dialysis or transplant. That’s why fifty percent is the best answer: it reflects the level at which functional loss becomes clinically apparent and progression to irreversible ESRD commonly begins. The other options describe losses that either would show symptoms earlier (a smaller loss) or represent much more advanced damage than the typical symptomatic threshold.