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The long-term outcome of cystinuria in Japan
1Department of Urology, Chiba University School of Medicine, Chiba, Japan. akakurak@medinfo.ho.chiba-u.ac.jp
Insights
Medical treatment for cystinuria, including hydration and thiol medications, shows a relatively good prognosis for urinary stones in Japanese patients. Lowering urinary cystine levels appears beneficial for managing this condition.
Area of Science:
- Nephrology
- Urology
- Medical Genetics
Background:
- Cystinuria is a genetic disorder characterized by recurrent urinary stone formation.
- Managing cystine stones requires long-term strategies to prevent recurrence and growth.
Purpose of the Study:
- To evaluate the long-term outcomes of cystinuria patients in Japan.
- To assess the impact of medical treatment on urinary stone events in cystinuria.
Main Methods:
- A retrospective study included 31 Japanese cystinuria patients followed for a mean of 89.5 months.
- Treatment involved forced hydration, urine alkalization, and thiol-based medications (D-penicillamine, alpha-mercaptopropionylglycine) for 28 patients.
- Stone events (new stone appearance or growth) were recorded and analyzed.
Main Results:
- The median stone event rate was 0.09 per year, with an overall rate of 0.19 per patient-year.
- Patients with favorable outcomes had lower average urinary cystine concentrations (221.2 mg/l) compared to unfavorable outcomes (303.3 mg/l), though not statistically significant.
- Urinary stone prognosis in Japanese cystinuria patients exhibited significant variability.
Conclusions:
- Long-term medical management, particularly reducing urinary cystine, appears beneficial for cystinuria patients.
- The prognosis for urinary stones in Japanese cystinuria patients is generally good but shows considerable variation.
- Further research may clarify the statistical significance of cystine concentration in treatment outcomes.
Abstract:
Recurrence of growth of urinary stone is frequently observed during the clinical course of cystinuria patients. The aim of the present study is to examine the long-term outcome of cystinuria in Japan and clarify the effects of medical treatment on urinary stone. Thirty-one patients with cystinuria who had been followed up longer than 6 months were included. The follow-up period was 6-264 months with a mean of 89.5 months. Stone event was defined as appearance of new stone or radiological evidence of stone growth. All patients were managed with forced hydration and urine alkalization. Twenty-eight patients were treated with administration of thiol such as D-penicillamine or alpha-mercaptopropionylglycine. Stone events per year ranged from 0 to 1.09 with a median of 0.09. Stone events per patient-year was 0.19 for all patients. The average urinary cystine concentration during treatment in the favorable outcome group (stone events per year < 0.3) was lower that that in the unfavorable outcome group (stone events per year >/=0.3); 221.2 +/- 75.2 vs. 303.3 +/- 93.5 mg/l, although the difference was not statistically significant. Prognosis of urinary stone in Japanese patients with cystinuria was relatively good with large variation. The medical treatment to reduce urinary cystine concentration would be useful for the management of cystinuria.