Effects of high diuresis on stone expulsion, urinary pH and crystalluria in stone form.

Objective : High urine volume is known to be an effective measurefor preven ting stone recurrence. However only few studies have investigated its effec ts on crystalluria and spontaneous passage of calculi. The aim of the study , was to assess the effects of high diuresis on stone expulsion and recurre nce. Patients and Methods : 219 patients were consulting for a first stone episo de in Urology units in the Mostaganem area between September 1996 and Decem ber 1999. All stones were under 6 min in size. The patients were divided in two groups : group I included 129 patients (68 males, 61 females) who agre ed to be on a high water intake, at least 3 liters per day, over a two mont hs period and to be followed periodically by crystalluria examination in th e first morning urine; group II included 90 patients (63 males, 27 females) who declined diuresis advice and urine collection for crystalluria examina tion. First morning urine collected in patients of group I were examined be fore (2.95 voidings per subject) and while on diuresis course (2.84 voiding s per subject). For each sample, the urine pH was measured and crystals wer e looked for by polarizing microscopy. Stones spontaneously passed were col lected and analyzed by infrared spectroscopy. Group II represented the cont rol group for stone passing and recurrence. Results : Crystalluria was present in 52.4% of urine samples before startin g diuresis and decreased at 22.9% of urine samples on high diuresis. Mean p H value increased from 5.73 +/- 0.46 before to 6.09 +/- 0.47 (p < 10-6) whi le on diuresis course in males and from 5,8 +/- 0,68 to 6,24 +/- 0,66 in fe males (p < 10-6). The most frequent crystalline species was weddellite. Ove r the study period, 98 patients (76%) in group I and only 13 patients (14.4 %) in group II passed stones spontaneously (p < 10-6 contre group I). No st one recurrence was observed in group I while 37.8% of patients in group II presented at least one stone recurrence (p < 10-7). Conclusion : A high diuresis is an effective measure (1) to make easier the passing of stone under 6 min in size; (2) to reduce the occurrence of crys talluria; (3) to reduce significantly, because of its favourable effect on urine pH, the formation of pH-dependent crystalline phases, thus decreasing heterogeneous nucleation process of calcium oxalate and stone recurrence.