EFFECT OF ALKALINE CITRATE THERAPY ON CLEARANCE OF RESIDUAL RENAL STONE FRAGMENTS AFTER EXTRACORPOREAL SHOCK-WAVE LITHOTRIPSY IN STERILE CALCIUM AND INFECTION NEPHROLITHIASIS PATIENTS

The natural history of post-extracorporeal shock wave lithotripsy resi dual stone fragments (clearance, growth and aggregation) is incomplete ly known, even though they are believed to constitute a risk in terms of new stone formation and persistent infection of the urinary tract. We addressed this issue and the hypothesis that alkaline citrate thera py improves residual stone fragment clearance in a 12-month followup s tudy. There were 40 sterile calcium and 30 struvite stone patients wit h residual fragments after extracorporeal shock wave lithotripsy (diam eter less than 5 mm.) consecutively enrolled and randomly assigned to a citrate therapy (6 to 8 gm. per day) or control (hygienic measures o nly) group. Infection stone patients also received adequate antibiotic therapy throughout the study. Among the patients in the untreated ste rile group 21% and 32% were stone-free at 6 and 12 months, respectivel y. In the infection group these figures were 27% and 40%, respectively . Among the untreated sterile calcium stone patients in whom clearance was not achieved a high percentage experienced residual fragment grow th or reaggregation. Citrate therapy significantly improved the stone clearance rate in the sterile (at 6 and 12 months 65% and 74% were sto ne-free, respectively) and infection (71% and 86%, respectively) stone patients, and prevented residual fragment growth or reaggregation in subjects in whom clearance was not achieved. The data show that growth and persistence are common in the natural history of residual stone f ragments. Citrate ameliorated the outcome of these residual fragments by reducing the growth or agglomeration, and by increasing the clearan ce rate in calcium oxalate and in infection stone patients.