title: Clinical value of crystalluria and quantitative morphoconstitutional analysis of urinary calculi.
abstract: Crystalluria is a marker of urine supersaturation with substances deriving from metabolic disorders, inherited diseases or drugs. The investigation of crystalluria must be done according to a protocol which includes the delivery to the laboratory of a proper urine sample, the use of a microscope equipped with polarized light, the accurate knowledge of urine pH, and a comprehensive examination of the crystals, which is based on their identification, quantification and size measurement. For unusual crystals, infrared spectroscopy may also be needed. If the formation of stones is always preceded by crystalluria, the reverse is not true. In addition to the crystalline composition, stone morphology provides valuable information on stone activity and, for some crystalline species, major information regarding the underlying pathology. Fourier transform infrared spectroscopy (FTIR) reliably identify specific forms of nephrolithiasis, as common-type stones made of calcium oxalate (CaOx) and/or calcium phosphate that is combined with morphology classification; using this method, stones may be classified into 6 types subdivided in 22 subtypes. The investigation of crystalluria is an inexpensive and valuable tool for the detection and the monitoring of inherited and acquired diseases associated with urinary stone formation or acute or chronic renal function impairment from intrarenal crystal precipitation. Selective FTIR identification of the composition of core (or the umbilication), middle part, and surface of every stone allows identification of the initiating lithogenic process (in the nucleus or in the Randall's plaque) and the factors which subsequently contributed to stone growth. In conclusion, the proposed morpho-constitutional method of urinary stone analysis, which moreover is rapid and low cost, provides clinically relevant orientations for targeted etiologic evaluation.
authors.affiliation: Laboratoire des Lithiases, Service des Explorations Fonctionnelles, Hôpital Tenon, APHP, Paris, France. Electronic address: vincent.frochot@aphp.fr.
authors.forename: Vincent
authors.initials: V
authors.lastname: Frochot
authors.affiliation: Laboratoire des Lithiases, Service des Explorations Fonctionnelles, Hôpital Tenon, APHP, Paris, France.
authors.forename: Michel
authors.initials: M
authors.lastname: Daudon
mesh_terms: D015415:Biomarkers / Q000737:chemistry / Q000652:urine; D002129:Calcium Oxalate / Q000737:chemistry / Q000652:urine; D002130:Calcium Phosphates / Q000737:chemistry / Q000652:urine; D003460:Crystallization; D006801:Humans; D007669:Kidney Calculi / Q000652:urine; D017550:Spectroscopy, Fourier Transform Infrared / Q000379:methods*; D016482:Urinalysis / Q000379:methods*; D014545:Urinary Calculi / Q000737:chemistry / Q000652:urine*
chemical_list: D015415:Biomarkers; D002130:Calcium Phosphates; D002129:Calcium Oxalate; C020243:calcium phosphate
keywords: Classification; Crystalluria; Etiology; Infrared spectroscopy; Morphology; Stone analysis