Study of calcium oxalate monohydrate of kidney stones by X-ray diffraction

Powder Diffraction (Impact Factor: 0.59). 06/2008; 23(2):S59-S64. DOI: 10.1154/1.2903738

ABSTRACT X-ray powder diffraction was used to study the phase composition of human renal calculi. The stones were collected from 56 donors in Vitória, Espírito Santo state, southeastern Brazil. An XRD phase quantification revealed that 61% of the studied renal stones were composed exclusively of calcium oxalate 34% formed only by calcium oxalate monohydrate COM and 27% presents both monohydrate and dihydratate calcium oxalate. The 39% multi-composed calculi have various other phases such as uric acid and calcium phosphate. Rietveld refinement of XRD data of one apparent monophasic COM renal calculus revealed the presence of a small amount of hydroxyapatite. The presence of this second phase and the morphology of the stone ellipsoidal indicated that this calculus can be classified as non-papillary type and its nucleation process developed in closed kidney cavities. In order to show some advantages of the X-ray powder diffraction technique, a study of the phase transformation of monohydrate calcium oxalate into calcium carbonate CaCO 3 was carried out by annealing of a monophasic COM calculi at 200, 300, and 400 ° C for 48 h in a N 2 gas atmosphere. The results of the XRD for the heat treated samples is in good agreement with the thermogravimetric analysis found in the literature and shows that X-ray powder diffraction can be used as a suitable technique to study the composition and phase diagram of renal calculi. © 2008 International Centre for Diffraction Data.

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: At the surface of attached kidney stones, a particular deposit termed Randall's plaque (RP) serves as a nucleus. This structural particularity as well as other major public health problems such as diabetes type-2 may explain the dramatic increase in urolithiasis now affecting up to 20% of the population in the industrialized countries. Regarding the chemical composition, even if other phosphate phases such as whitlockite or brushite can be found as minor components (less than 5%), calcium phosphate apatite as well as amorphous carbonated calcium phosphate (ACCP) are the major components of most RPs. Through X-ray absorption spectroscopy performed at the Ca K-absorption edge, a technique specific to synchrotron radiation, the presence and crystallinity of the Ca phosphate phases present in RP were determined ex vivo. The sensitivity of the technique was used as well as the fact that the measurements can be performed directly on the papilla. The sample was stored in formol. Moreover, a first mapping of the chemical phase from the top of the papilla to the deep medulla is obtained. Direct structural evidence of the presence of ACCP as a major constituent is given for the first time. This set of data, coherent with previous studies, shows that this chemical phase can be considered as one precursor in the genesis of RP.
    Journal of Synchrotron Radiation 05/2010; 17(3):374-9. · 2.19 Impact Factor


Available from
May 20, 2014