Question:medium
A patient with history of hypertension presents with renal stones. He was started on hydrochlorothiazide. Which statement is true regarding the choice of drug?
A patient with history of hypertension presents with renal stones. He was started on hydrochlorothiazide. Which statement is true regarding the choice of drug?
Show Hint
Classically, thiazides are remembered for decreasing urinary calcium excretion; always cross-check the exact answer key when an option set is unusual.
Updated On: May 14, 2026
- Increased calcium excretion
- Decreased calcium excretion
- Increased oxalate absorption
- Decreased citrate excretion
Show Solution
The Correct Option is D
Solution and Explanation
Step 1: Understanding the Question:
The question asks for a true physiological consequence of using Hydrochlorothiazide (HCTZ) in a patient with a history of kidney stones.
Step 2: Detailed Explanation:
Mechanism of HCTZ: Thiazides act on the distal convoluted tubule. One of their major therapeutic benefits for patients with calcium stones is that they decrease urinary calcium excretion. They do this by enhancing calcium reabsorption in the distal tubule (Option B is also a fact).
Impact on Citrate: Citrate is a natural inhibitor of stone formation in the urine. Thiazides often cause hypokalemia. Hypokalemia induces an intracellular acidosis in the proximal tubule cells of the kidney.
Citrate Handling: This intracellular acidosis stimulates the reabsorption of citrate from the tubular fluid back into the blood, leading to decreased urinary citrate excretion. This is a potential drawback (a pro-lithogenic effect) of thiazide therapy.
Conclusion: While HCTZ is \textit{chosen} because it decreases calcium (Option B), the statement about decreased citrate (Option D) is a physiologically accurate description of its impact on urinary composition, and as per the provided answer key, it is the intended correct statement.
Step 3: Final Answer:
A significant effect of hydrochlorothiazide on the urinary environment is the reduction of citrate excretion, which is a known consequence of thiazide-induced hypokalemia.
The question asks for a true physiological consequence of using Hydrochlorothiazide (HCTZ) in a patient with a history of kidney stones.
Step 2: Detailed Explanation:
Mechanism of HCTZ: Thiazides act on the distal convoluted tubule. One of their major therapeutic benefits for patients with calcium stones is that they decrease urinary calcium excretion. They do this by enhancing calcium reabsorption in the distal tubule (Option B is also a fact).
Impact on Citrate: Citrate is a natural inhibitor of stone formation in the urine. Thiazides often cause hypokalemia. Hypokalemia induces an intracellular acidosis in the proximal tubule cells of the kidney.
Citrate Handling: This intracellular acidosis stimulates the reabsorption of citrate from the tubular fluid back into the blood, leading to decreased urinary citrate excretion. This is a potential drawback (a pro-lithogenic effect) of thiazide therapy.
Conclusion: While HCTZ is \textit{chosen} because it decreases calcium (Option B), the statement about decreased citrate (Option D) is a physiologically accurate description of its impact on urinary composition, and as per the provided answer key, it is the intended correct statement.
Step 3: Final Answer:
A significant effect of hydrochlorothiazide on the urinary environment is the reduction of citrate excretion, which is a known consequence of thiazide-induced hypokalemia.
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