Eosinophiluria: accreditation with establishment of an inter-laboratories exchange

Abstract

Eosinophiluria corresponds to search eosinophils in urine. These are normally absent in urine, their presence could be associated with different clinical conditions affecting kidney or urinary tract. This analysis of medical biology laboratory listed in the French Nomenclature of acts of medical biology has to be validated according to norm NF EN ISO 15189. The principle of eosinophiluria method is based on eosinophils quantification by optical microscopy in a urine sample (urination) after staining. The aim of this article is to provide to biologists the eosinophiluria's clinical interest, but also bibliographic, technical and practical elements that can help them to establish eosinophiluria in their laboratories. The method validation elements were described for each item of SH Form 43. They include the analysis risks study, inter-operator variability, uncertainties, measurement range, comparison of methods based on the comparison of two staining, interferences, robustness, reliability of reagents, reference interval. Regarding accuracy, in absence of external quality assessment for this analysis, an inter-laboratory exchange has been set up in accordance with the requirements of the norm. Its organization is described. The performance of eosinophiluria was verified, recalling the importance of the pre-analytical conditions and the quality of staining. All of these data are presented and led the accreditation of eosinophiluria in our laboratory.