Analysis of renal calculi by X-ray diffraction and electron microprobe: a comparison of two methods

We analyzed 48 renal calculi by X-ray powder diffraction and electron microprobe techniques. In 35 of these, the presence of a minor constituent, not detected by X-ray diffraction, was revealed--hydroxyapatite was found in 24 stones, struvite in 6, and calcium oxalate in 5. The results of this study, as well as others, show that incomplete assignment of the crystalline constituents of urinary calculi is an inherent risk of the X-ray method and that conclusions concerning total chemical composition should be based on X-ray diffraction analyses coupled with data obtained from other analytical procedures.