Urolithiasis takes one of the leading places among the urological diseases in Russia [1]. Invasive technologies made the surgical treatment of urolithiasis relatively safe and routine [2]. However, simple removal of urinary stone without subsequent diet correction and taking special drugs in more than half of cases leads to a urolithiasis relapse [3].
Nowadays, the effective organization of the second stage of urolithiasis treatment is actual – conservative and drug metaphylaxis. It is a part of personalized patient management [2]. Since the choice of a metaphylactic strategy is impossible without a thorough study of the disease causes, it is necessary to develop an individual approach to clinical diagnosis and study of metabolomes urolithiasis [4 4a[A1] ].
Nowadays the following problematic aspects are described in the scientific literature: the phase composition study and frequency of the minerals presence [3, 5-22]; study of the urinary stone structure – phase composition in the core, middle zone and crust [11]; the relationship between the type of urinary stone (according to the main component) and territorial affiliation [7-11]; the study of the frequency of the mineral presence as an endemic characteristic [12, 23-26]; the relationship between the frequency of the mineral presence with age, gender, race and other characteristics [14-16, 27]; Hounsfield X-ray density study for various types of urinary stones [28, 29]; modeling of crystallization processes of urinary stones [30, 31]; statistical studies on the localization of urinary stones [1, 32-34] The published data are segmented, and researches individual methods were used for determination of elemental composition in small samples of urinary stones [35, 36]. There is an extremely small complex data about dependences between the phase and elemental composition of urinary stones in the published data.
This research is devoted to the urinary stones investigation using X-ray phase analysis (XRD) and inductively coupled plasma optical emission spectrometry (ICP-OES) in order to identify patterns of their formation and ways to prevent both primary and relapse of urolithiasis. These physico-chemical methods are used to obtain the complete information about the mineral and elemental urinary stones composition. The urinary stones of patients living with high anthropogenic load on the river Ob watershed were selected as objects for the study.
Results and discussion. Phase analysis
Some researchers [8, 12, 20] define metabolomes as one of the type of urinary stones – (“oxalates”, “phosphates”, “uric acid and its salts”), which contain more than 50% of the corresponding mineral in the phase composition.
In addition to this approach, there is another way to the data interpretation – the presence frequency of one or another mineral type in the investigating urinary stone [12, 14, 16]. XRD analysis have shown that the most commonly founded minerals are:
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«oxalates» – wevellite СаС2O4·(1+х)∙H2O (х ≈ 0.00 – 0.07) and weddellite CаC2O4·(2+х)∙H2O (х ≈ 0.30 – 0.37);
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«phosphates» – struvite MgNH4PO4·6H2O, hydroxylapatite Ca5(PO4)3(OH), brushite CaHPO4·2H2O;
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«uric acid and its salts» – uricite (мочевая кислота) C5H4N4O3, uric acid dihydrate C5H4N4O3·2H2O, ammonium urate (NH4)2C5H2N4O3.
Table 1 shows the comparison of results obtained by two adducted methods – “type” and “frequency” for Altai and Novosibirsk region. It should be noted that comparable values were obtained for oxalates and phosphates, the statistical processing results by two methods coincided for uric acid and its salts and cysteine.
We concluded that both approaches provided comparable data that could be subjected to comparative evaluation. Further, the authors provided the data on the frequency of the mineral presence.
Table 2 shows a statistical data comparison obtained by the XRD for the period 2011-17 and 2018-19 for Ob river watershed residents. The columns “oxalates”, “phosphates” etc. show the frequency of the particular mineral presence in the urinary stones of patients from various settlements for the indicated sample (see n – number of samples). It should be noted that the difference in the samples number does not mean a higher incidence in a particular locality but only reflects the amount of samples were submitted for analysis.
Table 2 represents the time interval 08.2017-07.2019 (“the present period”) which is less representative than the interval 01.2011-07.2017 (the “previous period”). Nevertheless, a significant increase in the stones number from Nefteyugansk – 12.2 times compared with the "previous period" and a 2-fold increase in stones from Nyagan attracts attention. A significant stones number for the "present period" from Nizhnevartovsk and Barnaul should also be noted. In the "present period" appear stones from Gorno-Altaysk and Salekhard. The explanation may be in the general improvement of the healthcare sector in the field of urolithiasis, the diagnostic methods modernization and methods for removing stones in these cities. As in the previous period, the largest number of urinary stones belongs to patients of regional center – Novosibirsk. In average, the share of men increased for all studied settlements, from 59.9 % to 70.0 % (see the TOTAL line).
The frequency of the mineral presence over the specified period has also changed. We keep in mind large settlements, the number of analyzed urinary stones in which was more than 30 – Barnaul, Nefteyugansk, Nizhnevartovsk and Novosibirsk. As could be seen from the table 2, the highest presence frequency belongs to oxalates (СаС2O4·(1+х)∙H2O wevellite and CаC2O4·(2+х)∙H2O weddellite). A slight decrease in the presence frequency of oxalates for Barnaul (by 2.2 %) and an increase for Nefteyugansk, Nizhnevartovsk and Novosibirsk (by 1.6-10.7 %) can be noted. At the same time, the presence frequency of phosphates and uric acid and its salts changed in opposite direction. For Barnaul, Nizhnevartovsk and Novosibirsk, the presence frequency of phosphates decreased (by 1.8-2.7 %), for Nefteyugansk it increased by 0.9 %. The latter may be due to the uneven urinary stones distribution over periods. The presence frequency of uric acid increased in Barnaul and Novosibirsk (by 1.6-3.3 %), while in Nizhnevartovsk and Nefteyugansk it decreased (by 5.5-11.6 %).
It is interesting that presence frequency of rare phases (cystine, quartz, calcite, etc.) has also changed. Changes were revealed for Barnaul, Nizhnevartovsk (an increase of 1.6%) and Novosibirsk (a decrease of 0.7 %).
On average, changes occurred in the Ob riverbed – the frequency of the presence of oxalates increased by 5.4 %; the frequency of the presence phosphates decreased by 4.1 %; the frequency of the presence of uric acid and its’ salts decreased by 1.4 %.
Perhaps described phenomenons are the result of a change in the nature of food consumed and import substitution policy in the Russian Federation.
Elemental analysis
To determine/establish interelement correlation an elemental composition of 55 urinary stones was investigated. The urinary stones were only oxalate type of minerals – «single-phase stones» (100 % wevellite, weddellite or a combination thereof). According to ICP-OES analysis in the urinary stones elements present: calcium range from up 8 to 32 % wt.; sodium range from up 0.05 до 0.30 % wt.; phosphorous range from up 0.16 to 2.0 % wt. In the urinary stones trace elements present: Bа, Cu, Fe, Li, Mg, Mn, Sr & Zn. The content varies these trace elements in the range up 2∙10-5 to 9.8∙10-2 % wt.
Comparing our results with data on single-phase stones published previously [20], we found some contradictions, for example, in trace elements Ni & Ti content. These trace elements are not detected by ICP-OES, the LODs are 4∙10-4% & 1∙10-4 % wt. Whereas the Authors of [20] Ni & Ti were determined more than 4∙10-4 % wt. Perhaps this is due to the peculiarities of the analysis technique. The authors of [20] used the X-ray analysis with synchrotron radiation [38].
It should be noted, that all analyzed single-phase oxalate stones contain phosphorus (0.16 – 2.0 % wt.). This fact gives This fact gives a reason to assume that in single-phase oxalate stones x-ray amorphous phosphates type of minerals presents. This is confirmed by literature data [39-41].
To determine/establish interelement correlation the Pearson linear correlation coefficient was used. The results of the correlation analysis are shown in table 3. As can be seen from the table, for K/Mg, K/P, K/Sr, Mg/Zn and P/Zn pairs an average positive correlation was established – R from 0.34 to 0.40. For Mg/Na and P/Na pairs strong positive correlation was established – 0.52 и 0.55, respectively. For Mg/P pair very strong positive correlation was established – 0.99. The average negative correlation between pairs of Ca/Mg, Ca/Na and Ca/P elements was also revealed – -0.43; -0.26; -0.42, respectively.
Considering the established positive interelement correlations it should be noted that potassium and magnesium are synergists, which explains the average positive correlation between them. Also it is known that potassium directly affects the urination, and there is a relationship between excess of potassium in the body and renal failure. The positive correlations between Mg and P, Mg and Zn, Mg and Na can be explained by the participation of magnesium in many functions of the body, including the synthesis and metabolism of the protein and enzymatic reactions. It is known that an excess of phosphates in the body leads to a decrease in the absorption of magnesium and zinc [42]. However, the correlation dependencies found may have a deeper physiological basis and reason, and the study of these causes was not part of the scope of this study.
The researchers haven’t common opinion about fundamental reasons determining the trace element composition of urinary stone. Some researchers associate the composition with the patient's region of residence [43], other researchers – with the phase composition of the samples [44]. In general, literature comparison is a tall order because of a wide range and differences in the applied research methods composition. In addition, the list of trace elements varies from work to work.
Conclusions
To summarize, the comprehensive analysis of more than 1000 urinary stones was carried out for Ob’ river watershed residents. For Altai and Novosibirsk regions comparable results were obtained by two methods of statistical processing - “type” and “frequency”. Both methods of statistical processing allow obtaining data that are allow obtaining data suitable for comparative evaluation.
Changing of the presence frequency of a particular mineral was measured by the XRD method for the previous period (01.2011-07.2017) and the present period (08.2017-07.2019).
The ICP-OES method has shown that the elemental composition of 55 urinary stones belonging to the oxalate type mineral consisted of the following macro-elements: Ca, Na, P (from 0.16 to 32% wt.) and trace elements: Ba, Cu, Fe, Li, Mg, Mn, Sr and Zn (from 2∙10-5 to 0.12% wt.).
The correlation analysis (linear Pearson correlation coefficient) has shown the average positive correlation between pairs of elements K/Mg, K/P, K/Sr, Mg/Zn and P/Zn (R from 0.34 to 0.40); a strong positive correlation for Mg/Na and P/Na pairs; and a very strong positive correlation for Mg/P pairs. The average negative correlation between pairs of Ca/Mg, Ca/Na and Ca/P elements has revealed.
The revealed time trends and inter-element correlation dependences for the investigated urinary stones allow us to understand their formation processes. The developed investigations expand the fundamental knowledge base about the mineral composition of analyzed metabolomes, which will contribute to the strategies development for personalized methods of metaphylaxis in the urolithiasis treatment.
This work was supported by the Russian Foundation for Basic Research, grant No. 20-015-00359 A.
A. Gubanov1,2, A. Tsygankova1,2*, I. Korolkov1,2, E. Filatov1,2,
E. Pechkovsky3,4, G. Yarin5, D. Safronov6,7, I. Vilgelmi,6,7
O. Lundovskaya1, A. Aleksandrova2, N. Glushkova2,8
1 Nikolaev Institute of Inorganic Chemistry SB RAS, Acad. Lavrentiev Ave. 3, Novosibirsk, 630090, Russia
2 Novosibirsk State University, Pirogov Ave. 2, Novosibirsk, 630090, Russia
3 INVITRO-Siberia Laboratory, Rimsky-Korsakova Str. 9, Novosibirsk, 630078, Russia
4 Institute of Chemical Biology and Fundamental Medicine SB RAS, Acad. Lavrentiev Ave. 8, Novosibirsk, 630090, Russia
5 Federal State Budgetary Institution of Healthcare Siberian District Medical Center of the Federal Medical and Biological Agency, Kainskaya Str. 13, Novosibirsk, 630007, Russia
6 Novosibirsk Research Institute of Traumatology and Orthopedics n.a. Ya.L. Tsivyan Frunze Ave. 17, Novosibirsk, 630091, Russia 5 Clinic NIITO, Frunze Ave. 19A, Novosibirsk, Russia
7 Clinic NIITO, Frunze Ave. 19A, Novosibirsk, 630091, Russia
8 Federal State Budgetary Institution of Science Institute of Geology and Mineralogy named after V.S. Sobolev SB RAS, Acad. Koptyuga Ave. Novosibirsk, 3, Novosibirsk, 630090, Russia