Which of the following is a radioliicent renal stone-

Ans. is 'd' i.e.. Xanthine Types of Renal Calculusa) Calcium oxalate calculus (Most common)# They have hard, small and jagged surfaceb) Phosphate calculus#Calcium phosphate but can be combined with ammonium and magnesium to form the triple phosphate calculus ie Calcium amnomium magnesium phosphate also k/a struvite stones.Smooth and dirty white and soltitary.Seen in alkaline urine esp with proteus infection which split urea to ammonia.This type of calculus may enlarge to fill all or most of the renal collecting system forming a staghorn calculus.c) Uric acid and urate calculusThese are radioluscentForm in acidic urineMost responsive to lithotripsyd) Cystein stonesUncommon, seen in cystinuriaAppear only in acidic urineThey-' are pink to yellow when first removed but they change colour to a greenish hue when exposed to air.Extremely hard stonesAre relatively resistant to fragmentation by ESWLe) Xanthine calculiAre radioluscentAre secondary to a congenital deficiency of xanthine oxidasef) Indinavir calculiIndinavir is a protease inhibitor used in AIDS patients. It results in calculi in ~6% pt. who use. indinavir.Indinavir calculi are radioluscentRare Calculio Silicate stonesAssociated with the long term use of antacids containing silicao Triamterene stonesAssociated with antihypertensive medications containing trimterene Are radioluscent