Medical Treatment of Cystinuria: Results of Contemporary Clinical Practice

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Abstract
We determined the efficacy of a contemporary medical regimen for treatment of cystinuria. A total of 16 patients with cystinuria was followed for 7 to 141 months (mean 78.1). Standard therapy included hydration and alkalization. D-penicillamine or alpha-mercaptoproprionylglycine was added for failure of hydration and alkalization to prevent new stones or stone growth, or to cause dissolution. Captopril was added for failure of or intolerance to D-penicillamine or alpha-mercaptopropionylglycine. Radiography was performed every 6 to 12 months, at which time stone events were documented. During hydration and alkalization 46 stone events occurred in 8 of 9 patients (1.6 events per patient-year). With addition of thiol derivatives 7 of 9 patients experienced 24 stone events, all 6 treated with hydration, alkalization and captopril experienced 10 events, and 4 of 5 treated with alkalization, thiols and captopril experienced 8 events (0.52, 0.71 and 0.54 events per patient-year, respectively). During a total treatment time of 104.1 patient-years 88 stone events occurred in 14 of 16 patients (0.84 events per patient-year). D-penicillamine and alpha-mercaptopropionylglycine are effective in decreasing the rate of stone formation in patients in whom hydration and alkalization failed. While captopril may also be beneficial in this setting, it does not appear to be as effective as D-penicillamine or alpha-mercaptopropionylglycine, and it does not clearly add clinical benefit to those thiols. Our study demonstrates that patients with cystinuria are at high risk for recurrence when treated with any contemporary medical program. This natural history must be considered when evaluating the long-term efficacy of newer or alternative modes of medical and urological treatment.