Uric acid kidney stones

1. Uric acid kidney stones
Risk factors
• Increased uric acid excretion: Gout,
myeloproliferative disorders
• Increased urine concentration: Hot, arid
climates; dehydration
• Low urine pH: Chronic diarrhea (GI
bicarbonate loss), metabolic
syndrome/diabetes mellitus
Pathophysiology
• Acidic urine favors formation of uric acid
(insoluble) over urate (soluble)
• Supersaturation of urine with uric acid
precipitates crystal formation
Clinical
characteristics
• Radiolucent stones (not visible on x-ray)
• Uric acid crystals on urine microscopy
• Urine pH usually <5.5
Treatment • Alkalinization of urine (potassium citrate)