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INTRODUCTION: The aim was to confirm that PSF (probability of stone formation) changed appropriately following medical therapy on recurrent stone formers. MATERIALS AND METHODS: Data were collected on 26 Brazilian stone-formers. A baseline 24-hour urine collection was performed prior to treatment. Details of the medical treatment initiated for stone-disease were recorded. A PSF calculation was performed on the 24 hour urine sample using the 7 urinary parameters required: voided volume, oxalate, calcium, urate, pH, citrate and magnesium. A repeat 24-hour urine sample was performed for PSF calculation after treatment. Comparison was made between the PSF scores before and during treatment. RESULTS: At baseline, 20 of the 26 patients (77%) had a high PSF score (> 0.5). Of the 26 patients, 17 (65%) showed an overall reduction in their PSF profiles with a medical treatment regimen. Eleven patients (42%) changed from a high risk (PSF > 0.5) to a low risk (PSF < 0.5) and 6 patients reduced their risk score but did not change risk category. Six (23%) patients remained in a high risk category (> 0.5) during both assessments. CONCLUSIONS: The PSF score reduced following medical treatment in the majority of patients in this cohort.

Original publication




Journal article


Int Braz J Urol

Publication Date





507 - 512


Adult, Aged, Calcium Phosphates, Citrates, Cohort Studies, Female, Humans, Magnesium, Male, Middle Aged, Oxalates, Probability, Reference Values, Reproducibility of Results, Risk Assessment, Risk Factors, Time Factors, Treatment Outcome, Uric Acid, Urolithiasis