A 66-year-old man with renal disease is discharged on a diuretic for edema. Which thiazide-related diuretic is appropriate for a patient with an eGFR of 27 mL/min/1.73 m²?

• A. Hydrochlorothiazide
• B. Chlortalidone
• C. Metolazone
• D. Indapamide

Answer: (C)

The key idea is that in reduced kidney function, not all thiazide-type diuretics work well. Traditional thiazides lose much of their effectiveness when the glomerular filtration rate falls because their blocking site in the distal tubule relies on adequate filtrate reaching that area. Metolazone, a thiazide-like diuretic, remains active at low GFR and can still produce meaningful diuresis around an eGFR of 27 mL/min/1.73 m². It’s often used to overcome diuretic resistance in edema due to CKD and is frequently given in combination with a loop diuretic to boost natriuresis. Be mindful of potential electrolyte disturbances, such as hyponatremia and hypokalemia, and monitor renal function and interactions.