Association of minor and trace elements with mineralogical constituents of urinary stones: A hard nut to crack in existing studies of urolithiasis

Abstract

The role of metals in urinary stone formation has already been studied in several publications. Moreover, urinary calculi can also be used for assessing exposure of humans to minor and trace elements in addition to other biological matrices, for example, blood, urine, or hair. However, using urinary calculi for biomonitoring of trace elements is limited by the association of elements with certain types of minerals. In this work, 614 samples of urinary calculi were subjected to mineralogical and elemental analysis. Inductively coupled plasma mass spectrometry and thermo-oxidation cold vapor atomic absorption spectrometry were used for the determination of major, minor, and trace elements. Infrared spectroscopy was used for mineralogical analysis, and additionally, it was also employed in the calculation of mineralogical composition, based on quantification of major elements and stoichiometry. Results demonstrate the applicability of such an approach in investigating associations of minor and trace elements with mineralogical constituents of stones, especially in low concentrations, where traditional methods of mineralogical analysis are not capable of quantifying mineral content reliably. The main result of this study is the confirmation of association of several elements with struvite (K, Rb) and with calcium phosphate minerals, here calculated as hydroxylapatite (Na, Zn, Sr, Ba, Pb). Phosphates were proved as the most important metal-bearing minerals in urinary calculi. Moreover, a significantly different content was also observed for Fe, Zr, Mo, Cu, Cd, Se, Sn, and Hg in investigated groups of minerals. Examination of such associations is essential, and critical analysis of mineral constituents should precede any comparison of element content among various groups of samples.

Urinary stones as a novel matrix for human biomonitoring of toxic and essential elements

“…Significant differences (p \ 0.001) were found for all tested elements except for K (p = 0.267). Similar results were found in our previous work with exception for Cr and Se where no significant difference was detected (Kuta et al 2013(Kuta et al , 2012. This is in agreement with work of Bazin and Giannossi (Bazin et al 2007;Giannossi et al 2013) who reported higher contents of metal elements in calcium oxalates (whewellite and weddellite) compared to uric acid stones.…”

“…Giannossi reported higher content of Zn in uric acid and cystine stones (Giannossi et al 2013), which is in contrast with our results and work of Bazin (Bazin et al 2007) where higher content of Zn was found in oxalates. On the other hand, Bazin and Giannossi (Bazin et al 2007;Giannossi et al 2013) detected higher representation of Cu in calcium-containing stones, which is not in agreement with results of our previous study where significantly higher content of Cu was found in uric acid stones compared to phosphates and oxalates (Kuta et al 2013).…”

“…Samples Environ Geochem Health identified by IR spectrometry as ''pure'' uric acid or whewellite were subjected to ICP-MS determination of phosphorus content, and samples exceeding 0.6 % of phosphorus content were excluded from further evaluation. Variable content of phosphate minerals in studied samples set can complicate data interpretation related to assessment of the effect of other factors such as age and sex as shown in our previous study (Kuta et al 2013).…”

“…As far as authors know, only a few studies were published regarding differences in contents of trace element in urinary stones related to geographical conditions (Kuta et al 2012;Pineda-Vargas et al 2009, smoking (Slojewski et al 2009) or to the effect of sex and age (Kuta et al 2012). However, use of urinary stones for biomonitoring can be limited by known mutual association of trace and minor elements with mineral constituents (Giannossi et al 2013;Abboud 2008a;Bazin et al 2007;Kuta et al 2013;Slojewski et al 2010;Wandt and Underhill 1988). These mutual associations then can act as a source of variability in the obtained results and the reason for their ambiguous interpretation.…”

“…These mutual associations then can act as a source of variability in the obtained results and the reason for their ambiguous interpretation. A thorough research on association of elements with urinary minerals is therefore crucial for assessment of the effect of other factors (such as age, sex, dietary habits, geography and others) on trace metal content (Kuta et al 2013).…”