Observations on Urinary Stone Weight Correlated with Composition

Abstract

The weight of 500 upper urinary tract stones is correlated here with qualitative and quantitative stone analysis findings. The average weight was 725 mg, but 65% of the stones weighed less than 200 mg. With increasing weight, a shift in dominance from calcium oxalate to triple phosphate occurs. Stone materials differ in weight distribution, and reports of composition in different weight ranges may facilitate comparison and compensate for bias in selection of stones for analysis. Quantitative observations on stones consisting of calcium oxalate mono- and dihydrate with apatite show that the proportions of these components are much the same in all weight ranges, but vary with the composition of the nucleus. This is taken to support the significance of apatite in such stones and to indicate that stones with different nuclei should be considered separately. Similar observations on pure calcium oxalate stones may support a primary role of calcium oxalate monohydrate in the deposition of many such stones. Weight data for bladder stones are presented briefly and show a wide range of weights for all types of composition.