Quantitative observations on the crystalline composition of urinary stones

Quantitative analytical findings on upper urinary tract stones from 500 patients are reported and compared to data in the literature. Methods of presentation of quantitative data are discussed. A wide range of findings between recurrent stones in the same patient and between stones from patients with the same cause of stone formation was found. No immediate clinical value of quantitation can be seen, but larger materials and correlation with metabolic investigations in stone formers may reveal correlations of clinical interest. Quantitative observations may identify groups of patients and types of stones not recognised on the basis of qualitative analysis. Examples of this are given for calcium oxalate-calcium phosphate stones and for stones containing brushite. The organic matrix which usually contributes 2-3% of stone mass was not considered, but distinctly visible and separate organic material in 7 stones was quantitated by visual estimate. 32 stones were incomplete, and their quantitation may not be wholly representative. Their exclusion, however, would have led to major bias because most were large and nearly half were triple phosphate stones, both properties being relatively rare. In cases of multiple stones, usually only one was quantitated. Seventy patients provided more than one stone for analysis (Otnes, 1983b), but except when specifically stated only the first stone is considered.