Critical Reappraisal of Methods for Measuring Urine Saturation with Calcium Salts

Autor: Martino Marangella, Pier Giuseppe Daniele, Demetrio Milea, Silvia Berto, Concetta De Stefano
Rok vydání: 2021
Předmět:
Calcium Phosphates
Dimer
Over-saturation
Potentiometric titration
Inorganic chemistry
030232 urology & nephrology
Calcium oxalate
Pharmaceutical Science
chemistry.chemical_element
Ionic bonding
Urinalysis
Calcium
Article
calcium phosphate
Analytical Chemistry
Kidney Calculi
03 medical and health sciences
chemistry.chemical_compound
QD241-441
0302 clinical medicine
Drug Discovery
calcium oxalate
Humans
citrate
Physical and Theoretical Chemistry
Ternary complex
Aqueous solution
Chemistry
nephrolithiasis
calcium oxalate
calcium phosphate
citrate
chemical speciation
oversaturation
Organic Chemistry
Hydrogen-Ion Concentration
chemical speciation
Calcium phosphate
Chemical speciation
Citrate
Nephrolithiasis
Calcium Oxalate
Potentiometry
Chemistry (miscellaneous)
030220 oncology & carcinogenesis
Molecular Medicine
Saturation (chemistry)
oversaturation
nephrolithiasis
Zdroj: Molecules
Volume 26
Issue 11
Molecules, Vol 26, Iss 3149, p 3149 (2021)
ISSN: 1420-3049
DOI: 10.3390/molecules26113149
Popis: Background: Metabolic and physicochemical evaluation is recommended to manage the condition of patients with nephrolithiasis. The estimation of the saturation state (β values) is often included in the diagnostic work-up, and it is preferably performed through calculations. The free concentrations of constituent ions are estimated by considering the main ionic soluble complexes. It is contended that this approach is liable to an overestimation of β values because some complexes may be overlooked. A recent report found that β values could be significantly lowered upon the addition of new and so far neglected complexes, [Ca(PO4)Cit]4− and [Ca2H2(PO4)2]. The aim of this work was to assess whether these complexes can be relevant to explaining the chemistry of urine. Methods: The Ca–phosphate–citrate aqueous system was investigated by potentiometric titrations. The stability constants of the parent binary complexes [Cacit]− and [CaPO4]−, and the coordination tendency of PO43− toward [Ca(cit)]− to form the ternary complex, were estimated. βCaOx and βCaHPO4 were then calculated on 5 natural urines by chemical models, including or not including the [CaPO4]− and [Ca(PO4)cit]4− species. Results: Species distribution diagrams show that the [Ca(PO4)cit]4− species was only noticeable at pH >
8.5 and below 10% of the total calcium. β values estimated on natural urine were slightly lowered by the formation of [CaPO4]− species, whereas [Ca(PO4)cit]4− results were irrelevant. Conclusions: While [CaPO4]− species have an impact on saturation levels at higher pHs, the existence of ternary complex and of the dimer is rejected.
Databáze: OpenAIRE
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