Concave urinary crystallines: direct evidence of calcium oxalate crystals dissolution by citrate in vivo.

The changes in urinary crystal properties in patients with calcium oxalate (CaOx) calculi after oral administration of potassium citrate (K3cit) were investigated via atomic force microscopy (AFM), scanning electron microscopy (SEM), X-ray powder diffractometry (XRD), and zeta potential analyzer. The AFM and SEM results showed that the surface of urinary crystals became concave, the edges and corners of crystals became blunt, the average size of urinary crystallines decreased significantly, and aggregation of urinary crystals was reduced. These changes were attributed to the significant increase in concentration of excreted citrate to 492 ± 118 mg/L after K3cit intake from 289 ± 83 mg/L before K3cit intake.

Property changes of urinary nanocrystallites and urine of uric acid stone formers after taking potassium citrate.

The property changes of urinary nanocrystallites in 20 cases of uric acid (UA) stone formers after 1 week of potassium citrate (K3cit) intake were comparatively studied by X-ray diffraction analysis, Fourier transform infrared spectroscopy, nanoparticle size analysis, and transmission electron microscopy. Before K3cit intake, the urinary crystallites mainly contained UA and calcium oxalate. After K3cit intake, the components changed to urate and UA; the qualities, species, and amounts of aggregated crystallites decreased; urine pH, citrate, and glycosaminoglycan excretions increased; and UA excretion, Zeta potential, and crystallite size decreased.