<prompt> Chronic Laxative abuse can result in the formation of which type of renal stone?XanthineCysteineAmmonium urateStruvite  <response>: C Ammonium urate?Ammonium Acid Urate Stones:Ammonium Acid Urate Stones represent less than 1 of all stones.Endemic ammonium acid urate urolithiasis is still observed because it comprises bladder calculi in children.Characteristic stone formation in laxative abuse:Laxative abuse acts a factor in kidney stone formation.Laxative abuse causes potassium loss:-As a compensation mechanism kidney produces large amount of ammonium.-Resulting in formation of uncommon stone type - ammonium acid urate.Conditions associated with ammonium acid urate crystallization include laxative abuse, recurrent urinary tract infection, recurrent uric acid stone formation, inflammatory bowel disease.Those with laxative abuse are strongly encouraged to develop a healthier bowel regimen.Pathogenesis:Urealysis provides an Alkaline Urine Environment sufficient concentrations of carbonate ammonia to induce the formation of infection stones.Because urease is not present in sterile human urine, infection with urease-producing bacteria is a pre-requisite for the formation of infection stones.Urea is hydrolyzed to ammonia and carbon dioxide by bacterial urease:-NH2 2 COH2 O-NH3 CO2 Alkaline urine that results from this reaction pH 7.2 to 8.0 favors the formation of ammonium:-NH3 H2 ONH4 OH-pK9.0TYPES OF RENAL CALCULUS:?Oxalate Calculus Calcium Oxalate:Majority are Oxalate stones, are irregular with sharp projections.Calcium oxalate monohydrate stone is hard radiodense.?Phosphate Calculus:Calcium phosphate often with ammonium magnesium phosphate Struvite is smooth dirty white.It grows in alkaline urine, especially when urea-splitting Proteus organisms are present.Calculus enlarges to fill most of the collecting system, forming a stag-horn calculus.Large stag-horn calculus may be asymptomatic for years, until it presents with haematuria, urinary infection or renal failure.?Uric Acid Urate Calculi:Hard, smooth, multiple multifaceted.Pure uric acid stones are radiolucent.CT scan differentiates from other causes of filling defects including tumours of the ureter.Most uric acid stones contain some calcium radio-opaque.?Cystine calculus:Uncommon, hereditary error of metabolism leads to cystinuria.Multiple, grow to form to cast of the collecting system, very hard radio-opaque. 