The differences between the urinary crystallites from patients with renal calculi and healthy subjects were compared using SEM, XRD, and nano-particle size analyzer, etc. These differences concern morphology, aggregation state, number, particle size, crystal phase and Zeta potential, etc. About 90% of the crystallites had the particle sizes less than 20 μm, the Zeta potential was -(113) mV, and the composition included a large proportion of calcium oxalate dihydrate (COD) crystals. By comparison, the urinary crystallites from patients with renal calculi had sharp edges and corners and exhibited significant aggregation. There were more crystallites with the size greater than 20 μm in comparison with those in healthy subjects, their Zeta potential was -(73) mV, and calcium oxalate existed mainly in the form of calcium oxalate monohydrate (COM) crystals. The above differences increased the aggregation trend of the crystallites in lithogenic urine and caused the probability of renal calculi formation to increase.
