Stone Morphology: Implication for Pathogenesis

摘要

Urinary stones of similar crystalline composition as identified by X-ray diffraction orFourier transform infrared spectroscopy (FT-IR) may exhibit distinct structures, which arereflected in distinctive stone morphology. Among factors involved in stone morphology-somereflecting lithogenic activity, others depending on the crystal shape, or on the propensity ofcrystalline phases to form large aggregates, finally the environment where the stone isgrowing-all of these factors influence the inner structure of the stone and its superficialcharacteristics. We present here examples of the clinical interest of refined morphologicexamination of stones, in addition to X-ray diffraction or FT-IR identification of its components.Such combination of methods allows the identification of specific etiologies among calciumoxalate stones, especially a morphological type pathognomonic of primary hyperoxaluria andother types related to distinct conditions of stone formation. Among phosphatic stones-inaddition to stone composition, which must be considered not only on the basis of the maincomponent, but also taking into account the minor crystalline phases, which often are clinicallyrelevant-morphological types also contribute to diagnosis of the underlying etiology, especiallyfor stones related to distal tubular acidosis. Finally, common purine stones also exhibit differentmorphologies related to stone composition and etiology: two main structures for uric acid andtwo for ammonium urate help to distinguish risk factors and lithogenic conditions involved inthe formation of these calculi. Morphologic examination is a simple, rapid and cheap methodthat points to specific diseases or lithogenic factors. Better awareness of its clinical relevanceshould lead to wider utilization.