Why does calcium oxalate crystallization sometimes still occur in individuals taking potassium citrate for kidney stones?

💡 Explanation

Potassium citrate treatment relies on increasing urinary citrate, which acts as a crystallization inhibitor. However, if calcium oxalate supersaturation is extremely high locally within the kidney tubules, the citrate concentration may be insufficient to completely prevent crystal formation, because the saturation of inhibitors is overwhelmed locally rather than fully suppressing crystallization. Therefore, crystals still form, rather than citrate directly dissolving existing crystals.

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