Stone clustering of patients with cystine urinary stone formation.

摘要

OBJECTIVES: To explore the history of symptomatic cystine stone formation. Cystinuria is a genetic defect that may result in the formation of recurrent cystine calculi. METHODS: Thirty-four patients with cystinuria were retrospectively evaluated for treatment patterns, medical prophylaxis, and renal outcome. Patients were offered a conservative surgical regimen and routine radiographic and laboratory follow-up and were encouraged to use medical prophylaxis. A Poisson regression model was used to analyze the patterns of stone formation. RESULTS: The mean age at presentation and at last follow-up was 18 and 38 years, respectively. Patients underwent a total of 249 procedures, with an average of 7.3 procedures per patient, including 37% percutaneous nephrolithotomies; 25.7% shock wave lithotripsy procedures; 22.1% ureteroscopies; 12.9% open lithotomies; and 1.6% nephrectomies. In 29% of patients, unilateral surgery only was required. With a conservative treatment regimen, no patient developed renal insufficiency or failure. The overdispersion estimated from the Poisson model was 5.03 (P <0.001) if patients were evaluated from birth to last follow-up and 2.06 (P <0.001) if followed from first presentation to last-follow-up, suggesting a clustering of stone events. Overdispersion was moderately related to increased age (older than 34 years). CONCLUSIONS: The results of our study showed that patients with cystinuria develop symptomatic calculi in clusters, with a slight predominance of stone formation after the age of 34. The cause of the stone clustering is unclear. Renal function can be preserved with a conservative surgical treatment protocol. Contemporary medical prophylaxis may be ineffective.