Cystine stones: review of a series of 116 cases

Introduction: Cystine stones is a rare disease, related to a genetic metabo lic disease. Its management must treat both the stones and their complicati ons, and prevent recurrences by controlling cystinuria. Objective: The objective of this study was to define the natural history of cystine stones, identify reliable diagnostic criteria and propose a simple treatment regimen. Material and Method: The authors studied the clinical, biochemical and radi ological data of a retrospective series of 116 cases treated by the same ur ologist between 1953 and 1999. Results: Cystinuria is often diagnosed in young adults on the basis of urin e biochemistry (Brand's reaction, urinary cystine assay) or spectrophotomet ric analysis of the stones or urinary crystals. This assessment, not perfor med routinely, must be guided by a family history, recurrent stones or foll owing failure of lithotripsy. The appearance of the stones, macroscopically a waxy, yellow radiologically only slightly opaque with a large component in the renal pelvis associated with a small round caliceal stones, is highl y suggestive. Radiological assessment by IVU is generally sufficient. Treat ment of the disease is medical and surgical: dietary measures, alkalinizati on of the urine and possibly drug treatments, are associated with extracorp oreal lithotripsy or surgical treatment. These modalities eliminate cystine stones in 70% of cases. Recurrent stones are observed in 42% of cases foll owed for more than 5 years, mainly due to the presence of residual fragment s (60% of recurrences). Surveillance and dietary measures must be maintaine d for life. Surveillance is based on biannual radiographic follow-up (plain x-rays +/- ultrasound) to detect and consequently treat small stones. A te st for cystinuria must be proposed to all relatives of affected patients. Conclusion: This disease presents very polymorphic clinical features and cl inical course. It can be responsible for impaired renal function and must t herefore be investigated in the presence of suggestive clinical signs or hi story to avoid a delayed diagnosis, as treatment modalities are available t o decrease the frequency of recurrence and which can potentiate treatment b y surgical or lithotripsy. However, there are no predictive factors of dete rioration of the disease, and biannual surveillance, for life, is essential to detect and treat small stones.