<prompt> Which of the followings renal stones may be large and still be asymptomatic for years: March 2011UrateOxalateStaghornCystine  <response>: Ans. C: Staghorn Phosphate calculus may enlarge to fill most of the collecting system, forming a staghorn calculus. Even a very large straghorn calculus may be clinically silent for years until it signals its presence by hematuria, urinary infection or renal failure Renal calculi: Calcium stones calcium oxalate and calcium phosphate makes up 75-85 of the total renal calculi Uric acid stones are radiolucent Uric acid stones are MC in men Struvite stones: - Occur mainly in women or patients who require chronic bladder catheterization - Result from UTI with urease producing bacteria proteus spp. - Grow in infected urine Cysteine stones are hard to break in ESWL 