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Hypocitraturia Stone Inhibition — ESENeph MCQ

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ModerateRenal Stone DiseaseHypocitraturia Stone InhibitionESENeph

A 55-year-old man with CKD G3b has recurrent calcium oxalate stones. His 24-hour urine shows low citrate excretion (1.2 mmol/day). Why is hypocitraturia important in stone formation?

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Correct answer: C — Citrate is a potent inhibitor of calcium crystal aggregation; low citrate removes this protection and promotes stone formation

Citrate is the most important urinary inhibitor of calcium stone formation. It binds calcium in the urine (reducing ionic calcium available for crystal formation) and directly inhibits calcium oxalate and calcium phosphate crystal growth and aggregation. Hypocitraturia (low urinary citrate) is found in 20-60% of stone formers. Potassium citrate supplementation corrects hypocitraturia and reduces stone recurrence. Causes of hypocitraturia include metabolic acidosis (CKD, RTA), hypokalaemia, high animal protein diet, and chronic diarrhoea.

Reference: EAU 2024 – Urolithiasis; Zuckerman and Assimos 2009 – Hypocitraturia