Medical treatment of cystinuria: evaluation of long-term results in 30 patients

OBJECTIVE: Because urinary hyperexcretion of cystine is permanent in homozy gous cystinuric patients, stone recurrence is frequent and may alter renal function. identification of factors predictive of success of medical treatm ent (no further urological procedure required) is therefore needed to impro ve patient management. PATIENTS AND METHODS: Thirty adult patients with homozygous cystinuria and urolithiasis were referred to the nephrology department of the Necker Hospi tal from 1963 to 1999, with a mean follow-up of medical therapy of 10.5 +/- 8.4 years. The basal treatment schedule was hyperdiuresis and alkalinizati on with thiol derivative (D-penicillamine or tiopronine) added when needed. RESULTS: Overall incidence of urological procedures decreased from 0.33/pt- year in the pretherapeutic period to 0.15 on treatment (p < 0.01), a 55% re duction. Sixteen patients (53%) did not require any urological procedure du ring follow-up. The only significant difference between those patients and the other 14 in whom medical therapy failed was the daily urine volume (3.2 l/day in the farmer compared with 2.4 l/day in the latter, p < 0.001). CONCLUSION: Regular medical therapy was able to stop stone disease activity in the long term in more than half of the patients. Sustained hyperdiuresi s, with a daily urine volume > 3 liters, appears as a major factor of thera peutic success, even in patients treated with thiols.