Which factor can lead to the formation of renal calculi?

• A. Alkaline Urine
• B. Acidic Urine
• C. High Protein Diet
• D. Low Fluid Intake

Answer: (A)

Urine pH affects how minerals dissolve or precipitate, influencing which crystals form. In alkaline (basic) urine, salts like calcium phosphate become less soluble and can crystallize, especially when an infection with urease-producing bacteria raises the pH and promotes struvite stone formation. This makes alkaline urine a factor that can lead to renal calculi across common stone types. By contrast, acidic urine tends to favor uric acid and certain other stones, and very low fluid intake increases stone risk by concentrating urine, but the direct pH-related precipitation that occurs with alkaline urine is a clear driver of stone development.