What GFR range defines CKD Stage 3, and what does this imply about kidney function?

• A. GFR 60-89 mL/min; mildly reduced.
• B. GFR 30-59 mL/min; indicates moderately reduced kidney function with potential for complications.
• C. GFR 15-29 mL/min; severely reduced.
• D. GFR <15 mL/min; kidney failure.

Answer: (B)

GFR is used to gauge how well the kidneys are filtering waste from the blood, and CKD stages are based on GFR ranges. CKD Stage 3 is defined by a GFR of 30–59 mL/min, with a common subdivision into 3a (45–59) and 3b (30–44). This means kidney function is moderately reduced: the kidneys still filter, but not at a normal rate, so waste and fluids can begin to accumulate more than usual.

What this implies is that there’s a higher risk of complications such as anemia from reduced erythropoietin production, electrolyte imbalances (like hyperkalemia and metabolic acidosis), bone-mineral disorders, and fluid overload. Blood pressure control and management of underlying causes (for example, diabetes or hypertension) become important to slow progression. Regular monitoring of kidney function and related labs is essential, and steps to protect kidney health—such as avoiding nephrotoxins, optimizing treatment, and potentially involving a nephrologist if decline continues—are typically pursued.