The structure of large lamellar urinary stones. A quantitative chemical analytic study applying a new classification...

To study the structural composition of 61 renal and 9 vesical large lamellated non-infection urinary tract stones, samples from successive layers were quantitatively analyzed with standard chemical techniques, but with a new classification based on percentage composition of ions rather than compounds. The commonest pattern of composition (n = 41) was that of the lamellar stones of one stone type (uric acid, oxalate, or phosphate) and group (according to % of indicating ion), followed by bilamellar stones of different stone types (17) or of one stone type but different groups (8). The other stones were trilamellar (3) or quadrilamellar (1) of different stone types. In the 29 stones with lamellae of different type and/or group, the chemical composition of successive layers seemed to confirm the correlation between uric acid and oxalate, rather than phosphate, ions and between oxalate and both uric acid and phosphate ions. An influence on these correlations either positive or negative, may be the responsible factor for specifying the type and group of a forming stone or layer of a stone. The observed ionic correlations within the stones seem to support the choice of the oxalate ion, in the uric acid or phosphate stones, and both of the uric acid and phosphate ions, in the oxalate stones, as indicating ions for grouping in our proposed classification of urinary stones.