Formation Mechanism of Magnesium Ammonium Phosphate Stones: A Component Analysis of Urinary Nanocrystallites

Abstract EN

The components of urinary nanocrystallites in patients with magnesium ammonium phosphate (MAP) stones were analyzed by X-ray diffraction (XRD), Fourier-transform infrared (FT-IR) spectrometer, high-resolution transmission electron microscopy (HRTEM), selected area electron diffraction (SAED), fast Fourier transformation (FFT), and energy-dispersive X-ray spectroscopy (EDS).

The main components of the stones were MAP hexahydrate (MAP·6H2O), magnesium hydrogen phosphate trihydrate (MgHPO4·3H2O), and a small amount of calcium phosphate (CaP), while the main components of urinary nanocrystallites were MgHPO4·3H2O, CaP, and MAP monohydrate (MAP·H2O).

MAP·H2O induced the formation of MAP stones as seed crystals.

MgHPO4·3H2O was accompanied by the appearance of MAP·6H2O.

The formation mechanism of MAP stones and influencing factors were discussed on the basis of the components of urine nanocrystallites.

A model diagram of MAP stone formation was also put forward based on the results.

Formation of MAP stones was closely related to the presence of high amounts of MAP crystallites in urine.

Urinary crystallite condition and changes in urine components could indicate the activity of stone diseases.