Calyx; Calculus clinical trials

Citrate Salts for Stone-free Result After Flexible Ureterorenoscopy for Inferior Calyx Calculi

The prevalence of urolithiasis is around 10 % in the French population. It is thus a major public health issue. When the stone is not spontaneously removed, interventions such as extracorporeal lithotripsy or flexible ureteroscopy (F-URS) are performed. F-URS is usually preferred in renal stones > 7 mm in comparison with lithotripsy, with better results. Efficacy of ureteroscopy is based on the "stone-free rate" (SFR) at 3 months. A SFR index is assessed according to the existence of residual fragments and their size. SFR score 1 (fragment ≤ 1mm) has been poorly studied, and is supposed to occur in 60% of cases. These residual fragments account for the high frequency of recurrence, probably favored by crystals aggregation and growth of these fragments under supersaturated urines. Indeed, calcium stones risk factors are urine supersaturation and crystal growth inhibitors deficiency. Citrate is the major crystal growth inhibitor in human urine. A hypocitraturia is reported in half of the lithiasic population. Consequently, citrate salts appear as an interesting therapeutic option, in order to slow crystal growth but also to chelate calcium, and consequently to solubilize stones in situ. However, to date, there is no available controlled study after surgical intervention such as flexible ureteroscopy. The aim of the investigator's study is to evaluate the efficacy of a 3-month potassium and magnesium citrate treatment following ureteroscopy on the elimination of residual fragments (SFR score 1).