Role of stone analysis in metabolic evaluation and medical treatment of nephrolithiasis

Background and Purpose: Comprehensive metabolic evaluation has become an im portant aspect of the management of recurrent nephrolithiasis, yet the role of stone analysis is often neglected or perhaps underestimated. The purpos e of this study was to determine the role of stone analysis in medical deci sion making in patients with recurrent nephrolithiasis. Materials and Methods: We evaluated 100 consecutive stone-forming patients who had undergone compositional stone analysis as well as comprehensive met abolic evaluation at our institution. An analysis of stone composition in r elation to metabolic disturbances was performed. Patients were stratified i nto two groups: calcium and non-calcium stone formers. Results: Patients having non-calcium stones were found to have a metabolic analysis reflecting specific metabolic disorders. Alternatively, patients w ith calcium stones were heterogeneous with regard to metabolic disorders, b ut there was a significant likelihood of renal tubular acidosis in those pa tients with calcium phosphate calculi. On the basis of these results, a sim plified metabolic evaluation and nonselective medical therapy based on ston e composition was formulated to facilitate assessment, management, and moni toring of stone disease. Conclusions: Compositional stone analysis should be an integral part of the metabolic evaluation of patients with nephrolithiasis. Moreover, stone ana lysis alone may provide guidance for therapeutic treatment and obviate a fo rmal metabolic evaluation.