Components of Urinary Crystallites in 56 Cases of Patients with Magnesium Ammonium Phosphate Stones

Abstract

Purpose) The formation of kidney stones related closely to the properties of urinary nanocrystallites. This study aimed to investigate the components of urinary crystallites in 56 cases of patients with magnesium ammonium phosphate (MAP) stones compared with the components of stones. (Methods) X-ray diffraction (XRD), Fourier-transform infrared (FT-IR) spectrometer, and fast Fourier transformation (FFT) of high-resolution transmission electron microscopy (HRTEM) were performed. (Results) The main components of MAP stones were found to be MAP hexahydrate (MAP•6H2O) and a small amount of magnesium hydrogen phosphate trihydrate (newberyite, MgHPO4•3H2O), calcium oxalate monohydrate (COM), calcium phosphate (CaP), and hydroxyapatite (HAP), whereas the main components of urinary crystallites in patients with MAP stones were newberyite, MAP monohydrate (MAPH2O), and small amounts of MAP•6H2O, COM, and CaP. (Conclusions) The formation of MAP stones was closely related to high concentration of MAP and newberyite crystals in urine. The formation mechanism and the influential factors of MAP stones were discussed on the basis of the components of urinary crystallites.