Why does increasing fluid intake help prevent renal calculi formation?

Why does increasing fluid intake help prevent renal calculi formation?

• A. It dilutes the urine, reducing concentration of stone-forming substances.
• B. It raises the pH of urine drastically.
• C. It increases intake of calcium.
• D. It reduces renal blood flow.

Answer: (A)

Increasing fluid intake helps prevent kidney stones by diluting the urine. When you drink more, urine volume rises, lowering the concentration of stone-forming substances such as calcium, oxalate, and uric acid. This reduced concentration lowers the likelihood that these substances will reach supersaturation and crystallize, which is how stones form. More urine flow also helps flush out small crystals before they can grow into larger stones. The other ideas aren’t the typical mechanism: simply changing urine pH isn’t guaranteed by fluids and can vary with what you drink; increasing calcium intake can raise urinary calcium and may not prevent stones; and reducing kidney blood flow would be harmful and has no role in stone prevention.

Increasing fluid intake helps prevent kidney stones by diluting the urine. When you drink more, urine volume rises, lowering the concentration of stone-forming substances such as calcium, oxalate, and uric acid. This reduced concentration lowers the likelihood that these substances will reach supersaturation and crystallize, which is how stones form. More urine flow also helps flush out small crystals before they can grow into larger stones.

The other ideas aren’t the typical mechanism: simply changing urine pH isn’t guaranteed by fluids and can vary with what you drink; increasing calcium intake can raise urinary calcium and may not prevent stones; and reducing kidney blood flow would be harmful and has no role in stone prevention.