Value of the urinary stone promoters/inhibitors ratios in the estimation of the risk of urolithiasis

An imbalance between urinary-promoting and -inhibiting factors has been sug gested as more important in urinary stone formation than a disturbance of a ny single substance. To investigate the value of promoter/inhibitor ratios for estimation of the risk of urolithiasis, urinary citrate/calcium, magnes ium/calcium oxalate, and oxalate/citrate x glycosaminoglycans ratios were d etermined in 30 children with urolithiasis, 36 children with isolated hemat uria, and 15 healthy control children. The cutoff points between normal chi ldren and children with urolithiasis, accuracy, specificity, and sensitivit y for each ratio were determined and compared with those of the 24-h urine calcium and oxalate excretion and urine saturation calculated with the comp uter program EQUIL 2. The neural network application (aiNET Artificial Neur al Network, version 1.25) was used for the determination of the cutoff poin ts for the classification of normal children and the urolithiasis group. Th e best test for differentiating stone formers from non-stone formers proved the aiNET determined cutoff values of oxalate/citrate x glycosaminoglycans ratio. The method showed 97.78% accuracy, 100% sensitivity, and 93.33% spe cificity. Two cutoff points between normal and urolithiasis groups were fou nd showing that the children with urolithiasis had ratio values either abov e 34.00 or less than 10.16. Increased oxalate excretion was linked to the f irst cutoff value (34.00), and decreased glycosaminoglycans excretion was t ypical of the second cutoff value (10.16).