What stone prevention strategy increases urinary citrate to help inhibit stone formation?

• A. Calcium carbonate therapy
• B. Diuretic therapy
• C. Potassium citrate therapy to alkalinize urine and inhibit stone formation
• D. Low-purine diet

Answer: (C)

Raising urinary citrate protects against stone formation because citrate helps prevent crystals from forming and growing. It does this in two key ways: first, citrate binds calcium in the urine, creating soluble calcium citrate and lowering the amount of free calcium available to form calcium-based stones; second, citrate is metabolized to bicarbonate, which alkalinizes the urine. A more alkaline urine environment helps prevent the crystallization of uric acid stones and reduces overall stone risk. The way to achieve higher urinary citrate is potassium citrate therapy, which delivers citrate to the urine and elevates its concentration while also raising pH. By contrast, calcium carbonate would add calcium to the urine and could promote calcium stones; diuretic therapy mainly affects urine volume or calcium handling without specifically increasing urinary citrate; a low-purine diet reduces uric acid but does not increase citrate.