An improved method for the routine biochemical evaluation of patients with recurrent calcium oxalate stone disease.
By means of a computerized calculation program, a simplified estimate of the ion-activity product of calcium oxalate was derived (AP(CaOx)-index), based on the 24-h urinary excretion of calcium (Ca), oxalate (Ox), magnesium (Mg), citrate (Cit) and the urine volume (V): (formula: see text) With urinary electrolyte values within the normal range, there was a good correlation between the AP(CaOx)-index and the more laboriously obtained ion-activity product (r = 0.997). To express the biochemical risk of CaOx stone formation a CaOx-risk index was designed, which also includes the inhibition of calcium oxalate crystal growth (I) and with all variables related to urinary creatinine (Cr): (formula: see text) The mean CaOx-risk index (+/-SEM) in urine from 100 normal men and 156 male stone formers were 648 +/- 27 and 1019 +/- 38 respectively (p less than 0.001). A risk index without inhibition index, had the corresponding values 366 +/- 14 and 527 +/- 17 (p less than 0.001).
D002129:Calcium Oxalate / Q000652:urine*; D002951:Citrates / Q000652:urine; D019343:Citric Acid; D003201:Computers; D006801:Humans; D006863:Hydrogen-Ion Concentration; D008433:Mathematics; D012306:Risk; D014545:Urinary Calculi / Q000175:diagnosis* / Q000652:urine
D002951:Citrates; D002129:Calcium Oxalate; D019343:Citric Acid