Crystal growth of calcium oxalate in urine of stone-formers and normal controls.

In this study, the relative crystal growth rate (Vcr) of calcium oxalate (Caox) and a number of other parameters were determined in 17-h daily (d) and 7-h nocturnal fractions (n) of whole urine from 20 recurrent Caox stone formers (SF) and 29 age-matched male normal controls (NC). Vcr, which was determined by the gel crystallization method (GCM), showed the largest difference between SF and NC among all parameters under investigation. Mean values (+/- SD) obtained for Vcr were: 0.73 +/- 0.58 (SF-d)/0.21 +/- 0.22 (NC-d; P less than 0.001) and 0.63+/- 0.58 (SF-n)/0.24 +/- 0.25 (NC-n; P less than 0.01). Significantly higher concentrations of Ca and lower concentrations of thermodynamic and kinetic effectors of Caox crystal growth were responsible for the higher crystal growth rates observed in SF as compared with NC, i.e., they should be partially causative in Caox urolithiasis. However, other properties of urine or the urinary tract (potentially, crystal agglomeration and adhesion) must be accounted for in the genesis of Caox stones.