<prompt> Most common type of renal stone?Calcium oxalateTriple phosphateStruvite stoneUrate stone  <response>: Ans. a Calcium oxalateRef.:Bailey and love 26th ed. 1292Types of Renal Stones Urolithiasis: Calcium stones 75-85 Made of calcium oxalate or Calcium oxalate plus calcium phosphate. Struvite stoneTriple phosphate stone 15 of cases Also known as magnesium-ammonium-phosphate stone Formed mainly after infection by urea splitting bacteria Proteus and some staphylococci - which causes alkaline urine - leads to precipitation of Mg -NH3 - PO4 Causes Staghorn calculi, which occupy large position of renal pelvis. Uric acid stone Common in patients with hyperuricemia except in patients with gout and in patients with rapid cell turnover Example- in Leukemia patients. Cause: Urine of pH less than 5.5 uric acid is insoluble in acidic urine a leading to saturation It is radiolucent stone. Cystine stone Due to genetic defect in renal absorption of amino acid cysteine a leading to cystinuria. 