[Metabolic investigation of calcium oxalate urinary lithiasis. Indicators of lithogenic risk: modalities, applications and perspectives].

Despite exhaustive metabolic investigations, calcium oxalate urinary stones often remain idiopathic and, in the absence of any objective aetiopathogenic parameter, the prevention of recurrences and follow-up are particularly problematical. Various indicators have been elaborated to quantify, the lithogenic risk, based on various parameters potentially involved in the crystallization process. Their disparity illustrates the difficulty of achieving such an objective as well as the progress in fundamental concepts and their frequent technical complexity penalizes their practical application. The performances of these indices, except in the hands of the team which has proposed them, often lack reproducibility and paradoxical or even contradictory findings are frequent. They may simply reflect the variability of the lithogenic process or may reflect the predominant role of potent inhibitors, especially macromolecules. The metabolic investigation of calcium oxalate urinary stones is initially limited to detection of lithogenic diseases amenable to specific treatment. After repeating the basic laboratory tests, recurrences, especially when they are unexplained, require more complex investigations. At the present time, applications of lithogenic risk indices are essentially confined to the field of clinical and basic research. Among the various indicators available, the urinary citrate/urinary calcium ratio and Parks' index appear to be particularly promising.