[Evolution of strategy to measure urinary supersaturation].

Urinary stones have an estimated lifetime morbidity of 15.1% in males and 6.1% in females ; in other words, one out of seven males and one out of fifteen females are affected with this disease at least once in their life. Previously, we reported a simple and easy method using microplates to measure the metastable limit (ML), which indicate the upper limit of supersaturation dissolution. In this study, we examined the usability of this microplate method. We confirmed that ML is correlated with the urinary calcium concentration in healthy subjects, single stone formers (SF), and recurrent stone formers (RSF). There was no significant difference between healthy subjects and RSF in urinary magnesium concentration, and ML was found to be correlated with urinary the concentration of oxalate and citrate acid in healthy subjects only. These results suggest that ML is a simple and easy way to measure the urinary calcium level and that ML could be a useful test item in outpatient settings as a convenient indicator for preventing recurrence of urinary stones in the future.