Naslov
The formation of struvite - basic investigations

Autori
Babić-Ivančić, Vesna ; Kontrec, Jasminka ; Brečević, Ljerka ; Kralj, Damir

Vrsta, podvrsta i kategorija rada
Sažeci sa skupova, sažetak, znanstveni

Izvornik
European Urology Meetings 2007 ; 2 (1) / Santos, Jose M. Reis ; Rao, Nagarajo - Arhnem : Elsevier, 2007, 74-74

Skup
5th eULIS Symposium 2007

Mjesto i datum
Cascais, Portugal; Lisabon, Portugal, 04.07.2007. - 07.07.2007

Vrsta sudjelovanja
Poster

Vrsta recenzije
Međunarodna recenzija

Ključne riječi
Struvite; urinary stone; infection stone; precipitation; transformation

Sažetak
Objectives: The formation of urinary stones is a serious health problem even today, especially in industrialized countries. Human renal stones (calculi) are mostly composed of calcium oxalate and phosphate salts (about 75 %) and of uric acid (about 10-12 %). A separate group of the phosphate-containing stones is the group of so-called “ infection stones” (25 % of occurrence). These stones are predominantly composed of struvite (MgNH4PO4∙ 6H2O) (10-20 %) often mixed with various amounts of hydroxyapatite (Ca5(PO4)3OH) and carbonate apatite (Ca5(PO4, CO3, OH)3OH). In this work, spontaneous precipitation of struvite and/or newberyite (MgHPO4∙ 3H2O), as well as the transformation of struvite into newberyite in the model system MgCl2-NH4H2PO4-NaOH-H2O have been studied under condition similar to physiological. Design and methods: For the construction of precipitation diagram, the precipitation systems were prepared by mixing equal volumes of magnesium chloride and ammonium dihydrogenphosphate solutions, previously preadjusted to pH = 7.4 by adding a required amounts of NaOH, and thermostated at 37 º C. The initial reactant concentrations were in the range of physiological magnesium, phosphate and ammonium concentrations. The precipitation systems thus prepared were tightly closed and aged for 24 h at 37 º C in a water bath without stirring. Then, pH of the solutions was measured and the samples were examined under light microscope. The precipitates were filtered throught 0.45 μ m Millipore filter and dried, and their composition was analyzed by X– ray diffraction, FT-IR spectroscopy and thermogravimetry. For the transformation experiments the systems were thermostated at 37 º C and stirred magnetically at a constant rate during the experiments. The changes of pH in the suspensions were recorded and the composition and morphology of precipitates were analyzed. Results: The results are represented in a form of precipitation diagram. Struvite was found to precipitate in nearly the whole concentration range investigated and also when Mg2+ and PO43- concentrations were within the range of concentrations of healthy person's urine. Newberyite was found to be a stable form at low pH (pH24h ≤ 6.4) and high concentrations of Mg2+ ions. At 37 º C dendrites crystals precipitated always in a mixture with elongated platelets crystals or with rhombohedral ones. Characterization of the crystals showed that elongated platelets and dendrites were struvite, the rhombohedral crystals were newberyite. Conclusion: The results indicate that under experimental conditions similar to that of urine, both struvite and newberyite can precipitate simultaneously. Their stability in the mixture depends on the pH of the system. The results are in accordance with the observations that under certain conditions struvite and newberyite coexist in renal calculi.

Izvorni jezik
Engleski

Znanstvena područja
Kemija, Temeljne medicinske znanosti

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