Hydrochlorothiazide (HCTZ) is a thiazide diuretic and it is often used in hypertensive patients with renal colic (pain) due to calcium stones (calcium oxalate or calcium phosphate). Because-
• It lowers blood pressure: Inhibits sodium-chloride symporter → leads to natriuresis and diuresis.
• Reduces urinary calcium excretion, which helps prevent calcium-containing kidney stone formation. (PYQ: NEET PG 2024)
• Caution: Not useful in uric acid or cystine stones.
Note: Renal colic refers to a sudden, severe pain caused by obstruction of the urinary tract, most commonly due to a kidney stone (renal calculus) blocking the ureter.
Figure- Mannitol 20% infusion (100ml)