Risk factors determining active urinary stone formation in patients with urolithiasis

AIMS: The goal of clinical and metabolic evaluation of patients with urinary stones is to identify patients at high risk for recurrent stone formation and as such, to allow the practitioner to suggest preventive therapies. However, knowledge about risk factors for active stone formation in patients with urolithiasis is limited. This study was initiated to assess the significance of several metabolic and clinical parameters for the determination of the risk of active stone formation. METHODS: Study in 320 consecutive outpatients referred to our clinic for metabolic analysis. Clinical and metabolic parameters were determined by standardized procedures of questionnaires, serum biochemical profiles and urinalysis. RESULTS: In 21.5% of 284 patients with complete data stone formation was active. Hypercalciuria, hypocitraturia and urinary tract infections had odds ratios for active stone formation above 2.5, whereas the odds ratio of a positive family history was 0.38. Hyperuricosuria, hyperoxaluria and a low urinary volume did not influence the risk for active stone formation. CONCLUSION: The risk profile for active stone formation differs from the risk profile for urolithiasis in general. Metabolic evaluation and determination of those risk factors in patients with urolithiasis might improve the estimation of the risk of future stone formation