Cystine stones: the impact of new treatment.

The hardness and frequent recurrence of cystine stones present a special challenge to the urologist. In this study, 15 cystinuric patients (11 males, 4 females; mean age 36 years, range 17-54) were treated and followed up over a period of 30 months (range 2-40). Most patients had previous history of open surgery. The diagnosis of cystinuria was confirmed by metabolic studies and infrared spectrometry of stones. Over the follow-up period recurrence was observed in 23 instances in 11 patients, leading to 38 "stone treatments" on 74 cystine stones. The percutaneous approach was used alone in 9 cases and in association with extracorporeal shock wave lithotripsy (ESWL) in 9 cases. ESWL was used alone in 18 cases. Medical treatment included high fluid intake, alkalinisation and Thiola (tiopronin, N-(2-mercaptopropionyl)glycine) in 6 patients. The overall stone-free rate assessed 3 months after treatment was 44.7%, which compares poorly with the rate for non-cystine stones. The recurrence rate is very high and instrumental treatment should not therefore be used excessively; it is indicated only for stones that are symptomatic or refractory to intensive medical therapy.