Comparison of Physicochemical Properties of Nano- and Microsized Crystals in the Urine of Calcium Oxalate Stone Patients and Control Subjects

Abstract

Purpose. To compare the properties of different sizes of urinary crystallites between calcium oxalate (CaOx) calculi patients and healthy controls.Methods. We studied the average particle size, size distribution, intensity-autocorrelation curve, zeta potential (ζ), conductivity, mobility, aggregation state, and stability of different sizes of urinary crystallites by nanoparticle size analysis and transmission electron microscopy after filtration through a microporous membrane with an aperture size from 0.22 μm to 0.45, 1.2, 3, and 10 μm.Results. The urinary crystallites of the CaOxcalculi patients were uneven and much easy to aggregate than those of controls. The number of large-sized crystallites of the patients was significantly more than that of the controls. The main components of the nanosized urinary crystallites in patients were CaOxmonohydrate (COM), uric acid, andβ-calcium phosphate, and these components were basically similar to those of the microsized urinary crystallites. The urinary crystallites of the calculi patients were easier to aggregate than that of the controls, and the small-sized urinary crystallites were much easier to agglomerate.Conclusions. The urinary system of CaOxcalculi patients is unstable and highly susceptible to urinary crystallite aggregation. The rapid aggregation of urinary crystallites may be the key factor affecting urolithiasis formation.