Biomineralogical analysis of human urinary stones

We present a study of a reference collection of urinary stone samples from men and women aged 27—83 years, as well as urine from patients with urolithiasis and chronic pyelonephritis, using a wide range of modern experimental research methods. The chemical and phase composition, trace element content, amino acid composition and content in proteins, and the isotopic composition of carbon and nitrogen are analyzed. Biominerals are found in the urinary stones, covering virtually the entire modern range of mineral types: elementary substances (metals), chalcogenides (sulfides), halides (chlorides), oxides (magnetite, SiO2 phase), silicates (aluminosilicates), and oxygen salts. In addition to minerals, the stones also contain so-called mineraloids, represented by hydrous calcium oxalates and uric acid. Fifteen protein amino acids, including seven essential ones, are identified in the studied samples. Three amino acids contain a small amount of the D-enantiomer. The isotopic composition of carbon and nitrogen in organic matter found in human stones and urine is unique and differs from that found in human bones, the Earth's atmosphere, and sedimentary rocks. However, urinary stones share a carbon isotopic composition similar to organic polymers formed by modern volcanism.