Fluid Intake Stone Prevention Priority — ESENeph MCQ

Instant feedback + full explanation. One question, done properly.

EasyRenal Stone DiseaseFluid Intake Stone Prevention PriorityESENeph

A 19-year-old man is investigated for recurrent bilateral renal stones. 24-hour urine shows: calcium 2.1 mmol/day (normal), oxalate 0.9 mmol/day (elevated), citrate 0.8 mmol/day (low), urine volume 1.2 L/day. Stone analysis reveals calcium oxalate monohydrate. He has no family history of stones and eats a normal diet. What is the single most impactful dietary intervention?

Educational content. Not a substitute for clinical judgement or local policy.

Reveal the answer and explanation

Correct answer: B — Increase fluid to urine output above 2.5 litres/day

Increasing fluid intake to achieve urine output >2.5 L/day is consistently the single most impactful intervention for stone prevention across all stone types. This patient has multiple metabolic abnormalities (hyperoxaluria, hypocitraturia, low urine volume), but the low urine volume is the most easily correctable and highest-yield target. Calcium restriction is not recommended as it paradoxically increases oxalate absorption. While potassium citrate is also appropriate for hypocitraturia, fluid intake remains the foundation of stone prevention per EAU and AUA/CUA guidelines. The competing options do not fit the renal phenotype, temporal relationship, treatment threshold or safety constraint described. Management still requires confirmation of current medicines, renal trajectory and relevant contraindications, followed by timely biochemical and clinical reassessment. Escalate urgently if life-threatening electrolyte disturbance, respiratory compromise, shock, neurological deterioration or a dialysis indication develops.

Reference: EAU 2023 – Urolithiasis Guidelines; NICE 2019 – NG118 Renal and Ureteric Stones: https://www.nice.org.uk/guidance/ng118/chapter/recommendations