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Journal of Nanomaterials
Volume 2015, Article ID 498932, 9 pages
Research Article

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

Institute of Biomineralization and Lithiasis Research, Jinan University, Guangzhou 510632, China

Received 27 January 2015; Revised 19 March 2015; Accepted 19 March 2015

Academic Editor: Hassan Karimi-Maleh

Copyright © 2015 Xin-Yuan Sun et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


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.