Quality Assessment of Urinary Stone Analysis: Results of a Multicenter Study of Laboratories in Europe.

Roswitha Siener,Olivier Traxer,Noor Buchholz,Palle J Osther,Eau Section Of Urolithiasis (Eulis) ,Thomas Knoll,Bernhard Hess,Alberto Trinchieri,José Reis-Santos,Kemal Sarica,Michel Daudon

doi:10.1371/journal.pone.0156606

Roswitha Siener, Olivier Traxer + Show 9 more

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https://doi.org/10.1371/journal.pone.0156606

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Abstract

After stone removal, accurate analysis of urinary stone composition is the most crucial laboratory diagnostic procedure for the treatment and recurrence prevention in the stone-forming patient. The most common techniques for routine analysis of stones are infrared spectroscopy, X-ray diffraction and chemical analysis. The aim of the present study was to assess the quality of urinary stone analysis of laboratories in Europe. Nine laboratories from eight European countries participated in six quality control surveys for urinary calculi analyses of the Reference Institute for Bioanalytics, Bonn, Germany, between 2010 and 2014. Each participant received the same blinded test samples for stone analysis. A total of 24 samples, comprising pure substances and mixtures of two or three components, were analysed. The evaluation of the quality of the laboratory in the present study was based on the attainment of 75% of the maximum total points, i.e. 99 points. The methods of stone analysis used were infrared spectroscopy (n = 7), chemical analysis (n = 1) and X-ray diffraction (n = 1). In the present study only 56% of the laboratories, four using infrared spectroscopy and one using X-ray diffraction, fulfilled the quality requirements. According to the current standard, chemical analysis is considered to be insufficient for stone analysis, whereas infrared spectroscopy or X-ray diffraction is mandatory. However, the poor results of infrared spectroscopy highlight the importance of equipment, reference spectra and qualification of the staff for an accurate analysis of stone composition. Regular quality control is essential in carrying out routine stone analysis.

Highlights

Prevalence and incidence of urolithiasis in industrialized countries have markedly increased over the past decades
Depending on different risk factors, calcium oxalate stone disease is likewise characterised by a high frequency of recurrence [8]
One laboratory reported the application of X-ray diffraction (XD) and another of chemical analysis (CA)

Summary

Introduction

Prevalence and incidence of urolithiasis in industrialized countries have markedly increased over the past decades. The prevalence of urinary stone disease in the Unites States significantly increased from 5.2% in 1988 to 1994 to 8.8% in 2007 to 2010 [1,2]. In Germany, the prevalence of urolithiasis markedly increased from 4.0% to 4.7% and the incidence from 0.54% to 1.47% between 1979 and 2001 [4]. The high incidence of recurrence indicates that metaphylactic measures after stone removal are still inadequate. Patients at high risk of recurrent stone formation are those with infection stones, uric acid, urate (i.e. monoammonium urate, monopotassium urate and monosodium urate monohydrate), brushite and genetically determined stones (i.e. cystine, 2,8-dihydroxyadenine and xanthine stones) [7]. Depending on different risk factors, calcium oxalate stone disease is likewise characterised by a high frequency of recurrence [8]. For effective management of the stone-forming patient, accurate stone analysis is, an essential component of the diagnostic work-up and a prerequisite of metabolic evaluation [9]

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