SO014CHANGES IN CHARACTERISTICS OF CRYSTALLURIA IN PATIENTS WITH RECURRENT NEPHROLITHIASIS

Abstract

Abstract Background and Aims The study of crystals in the urinary sediment finds application in the diagnosis of hereditary or metabolic nephrolithiasis and in the identification of crystals from drugs. Method We conducted a thorough microscopic urine examination, focused on the determination of crystalluria, associated with the metabolic study at baseline and about 6 months after the start of a metaphylactic therapy, in 21 patients with recurrent nephrolithiasis, followed at the Metabolic Stone Clinic of our Institution. The analysis of the crystals was performed in parallel and blind through direct microscopic examination (MD) and automated instrumentation (SA) (SediMax analyzer - Menarini Diagnostics) of our institution. We used a semi-quantitative approach for both methods. Results We examined 42 sediments (21 at baseline and 21 after an average follow-up of 196±88 days) from 21 patients (8 females, 13 males), all of them showing calcium oxalate crystalluria. The analysis on baseline evaluation and follow-up on both Crystalluria MD and crystalluria SA through spaghetti plots showed a tendency to reduction of severity for the first one only. This trend is consistent with the data obtained from the metabolic studies: urinary oxalate and calcium excretions, the main drivers of calcium oxalate crystallization, which showed decreasing levels. The same examination for urinary citrate excretion showed a rising trend, again in accordance with the on-going changes in urine lithogenic profile. Conclusion The study of crystals in the urinary sediment, repeated over time, may represent a further indicator of the effectiveness of metaphylactic therapy and an indicator of patient adherence to the prescription in metabolic calcium oxalate nephrolithiasis.