Question:medium
Laxative abuse causes which of the following renal stones?
Laxative abuse causes which of the following renal stones?
Show Hint
Think potassium loss from chronic diarrhoea and compensatory renal ammonium production.
Updated On: Jun 23, 2026
- Uric acid
- Ammonium urate
- Struvite
- Ca oxalate
Show Solution
The Correct Option is B
Solution and Explanation
Step 1: The question links a specific behaviour (laxative misuse) to a specific stone chemistry, so the answer must be the stone whose formation pathway depends on that behaviour rather than the most frequent stone overall.
Step 2: Chronic laxative use produces ongoing watery diarrhoea. This drains potassium and water, producing volume depletion and hypokalaemia.
Step 3: The hypokalaemic, volume-depleted kidney ramps up ammoniagenesis, dumping ammonium into a concentrated, low-volume urine. Excess ammonium plus urate ions crystallise as ammonium acid urate.
Step 4: Eliminating distractors: $\text{calcium oxalate}$ is the overall commonest but not behaviour-specific; uric acid stones need a persistently acidic urine; struvite ($\text{MgNH}_4\text{PO}_4$) needs urease-splitting bacteria. None of these is driven by laxative abuse.
Step 5: Therefore the stone uniquely associated with laxative abuse is ammonium urate.\[\boxed{\text{Ammonium urate}}\]
Step 2: Chronic laxative use produces ongoing watery diarrhoea. This drains potassium and water, producing volume depletion and hypokalaemia.
Step 3: The hypokalaemic, volume-depleted kidney ramps up ammoniagenesis, dumping ammonium into a concentrated, low-volume urine. Excess ammonium plus urate ions crystallise as ammonium acid urate.
Step 4: Eliminating distractors: $\text{calcium oxalate}$ is the overall commonest but not behaviour-specific; uric acid stones need a persistently acidic urine; struvite ($\text{MgNH}_4\text{PO}_4$) needs urease-splitting bacteria. None of these is driven by laxative abuse.
Step 5: Therefore the stone uniquely associated with laxative abuse is ammonium urate.\[\boxed{\text{Ammonium urate}}\]
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