<prompt> Which of the following is a radiolucent stone?Uric acidOxalateCysteineTriple phosphate  <response>: Ans: a Uric acid Ref: Bailey and Love, 24th ed, p. 1317Pure uric acid stones are radiolucent and appear in an excretory urogram as filling defects.Uric acid stones if contain calcium, will cast a faint radiological shadow.Examples for radiolucent stones Uric acid Dihydroxy adenine Orotic acid Xanthine Allopurinol Triamterine and Indinavir induced stones. 