<prompt> Chronic laxative abuse can result in the formation of which of the following renal stones?Uric acidAmmonium urateStruviteCa oxalate  <response>: Ans. b. Ammonium urateTYPES OF NEPHROLITHIASISTypeFrequencyEtiology and characteristicsTreatmentCalciumoxalatecalciumphosphate83The most common causes are idiopathichypercalciuria and1deg hyperparathyroidism. Canalso see in fat malabsorption oxalate absorption Alkaline urine.RadiopaqueHydration, dietary sodium and protein restriction, thiazide diuretics. Do not calcium intake can leadto hyperoxaluria and an risk of osteoporosisStruviteMg-NH4 -PO4 or triple phosphate9Associated with urease producing organisms e.g. Proteus. Form staghorn calculi. Alkaline urine. RadiopaqueHydration; treat UTI if present; surgical removal of staghorn stoneUric acid7Associated with gout, xanthine oxidase deficiency, and high purine turnover states e.g. chemotherapy. Acidic urine pH 5.5. Radiolucent on plain film, but detectable with CTHydration; alkalinize urine with citrate, which is converted to HC03- in the liver; dietary purine restriction and allopurinolCystine1Due to a defect in renal transport of certain amino acids COLA--cystine, ornithine, lysine, and arginine. Hexagonal crystals. Urinary cyanide nitroprusside test. RadiopaqueHydration, dietary sodium restriction, alkalinization of urine, penicillamineIndinavirRarePatients will be on protease inhibitors or HIV. Stones consist of precipitated indinavir. Radiolucent on KUB and CTHydration, surgical removal.AmmoniumUrateRareTypically occurs in the setting of chronic diarrheal state Inflammatory bowel disease, laxative abuse. The gastrointestinal losses of fluids, sodium and potassium content, leaving ammonium excreted in response to gastrointestinal alkali loss as the major cation in urine to bind urate and precipitated as ammonium urateAntibiotics, in case of urinary tract infection, discontinuation of offending agent like laxative abuse, volume repletion and potassium supplementation as neededCRYSTALS FOUND IN NEPHROLITHIASISTypeShapeFigureCalcium oxalateEnvelope-shapedStruviteMg-NH4-P04Coffin lid-shapedUric acidRhomboid shapedCystineHexagonal shaped 