CKD stage 5 is defined as which of the following?

• A. eGFR 15-29
• B. eGFR <15 mL/min/1.73 m2 or patient on dialysis
• C. eGFR ≥90 with dialysis
• D. eGFR 30-59

Answer: (B)

Stage 5 represents end-stage kidney disease, where kidney function is extremely reduced. It is defined by an eGFR below 15 mL/min/1.73 m^2, or by being on dialysis. This means that once filtration is that low, the kidneys can no longer sustain life without renal replacement therapy, such as dialysis. If someone is on dialysis, they are classified as stage 5 regardless of their current eGFR, because dialysis dependence marks irreversible kidney failure. Understanding this threshold helps distinguish stage 5 from earlier stages, where eGFR values are higher but still indicate progressive loss of function.