Hydration properties of urinary compounds obtained from normal and stone former individuals. An NMR study

Proton magnetic resonance measurements were performed on lyophilized urine samples collected from 10 recurrent calcium oxalate stone former (SF) patients, 10 thiazide treated (TSF) patients and 14 normal (N) individuals. T1 and T2 relaxation times were measured with a Bruker PC Multispec at 20 MHz and 37C on the lyophilized sample and thereafter during gradual controlled rehydration. The prolongation of the relaxation times was found to be significantly different (p less than 0.001) for the SF and N groups, while it was similar for the SF and TSF groups. Water compartmentalization was then calculated according to the Fast Proton Infusion model. After the addition of similar amounts of water, significantly (p less than 0.01) different hydration fraction (HF) and fraction bound (FB) values were calculated for the N and SF groups, while similar values were obtained for the SF and TSF groups. The results reflect differences in the urinary contents and/or properties of N and SF groups. It seems that there are more hydrophilic compounds in the urine of N individuals than in that of SFs. It can be speculated that the urinary macromolecules of SFs differ from those of Ns in the amount of water binding sites and in the water multilayer thickness surrounding them. The present results point to possible pathogenic differences between SF and N individuals.