[Calcium oxalate activity products and discriminant analysis of urinary parameters as basis for a calcium oxalate screening program (author's transl)].

The values of 7 urinary parameters in divided urine collections were measured in 20 patients with calcium oxalate stones and ten normal persons. On this basis the thermodynamic stone formation risk was calculated for the different urine collections. Stone formation risk in the 0-6 a.m. urine fractions appeared to be the most important. The risk of stone formation is significantly increased in the time from midnight to 6 a.m. To detect the risk situation the determination of oxalic acid, calcium, potassium and inorganic sulfate in night urine is adequate.