Abstract
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.
Highlights
IntroductionUrinary stones can be divided into acidic (e.g., uric acid and cystine), neutral (e.g., calcium oxalate (CaOx)), and alkaline (e.g., magnesium ammonium phosphate (MAP)) stones based on their chemical properties
Urinary stones can be divided into acidic, neutral (e.g., calcium oxalate (CaOx)), and alkaline (e.g., magnesium ammonium phosphate (MAP)) stones based on their chemical properties
The components of six MAP stones were characterized by X-ray diffraction (XRD) and Fourier-transform infrared (FT-IR) spectra
Summary
Urinary stones can be divided into acidic (e.g., uric acid and cystine), neutral (e.g., calcium oxalate (CaOx)), and alkaline (e.g., magnesium ammonium phosphate (MAP)) stones based on their chemical properties. Indices that can be used to predict the formation and recurrence risk of renal stones are unavailable. MAP, the most common component of alkaline stones, contains MAP hexahydrate (struvite, MgNH4PO4⋅6H2O) and magnesium hydrogen phosphate trihydrate (newberyite, MgHPO4⋅3H2O). MAP accounts for approximately 10% to 15% of all stone components [3]. Other alkaline stones comprise carbapatite (Ca10(PO4)6CO3), hydroxyapatite, and monoammonium urate. MAP is defined as infective stones associated with urinary tract infection. The morbidity of infective stones constantly decreases, the recurrent rate of infective stones is higher than that of other stones, and female morbidity is higher than male morbidity [4]
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