Multicentre physiological reference values for some urinary component-to-creatinine (creatininium) concentration ratios.

Nine clinical laboratories in different regions of Spain have shared the search for reference individuals and the production of reference values for urinary component-to-creatininium concentration ratios measured in first morning urine samples using RD/Hitachi analysers. These urinary quantities include albumin, calcium(II), chloride, magnesium(II), phosphate, potassium ion, protein, sodium ion, urate and urea. All the logistic work was done in co-operation with the reagents' and analysers' supplier (Roche Diagnostics España, S.L., Sant Cugat del Vallès, Catalonia, Spain). From the blend of reference values obtained by each laboratory, the multicentre reference limits were estimated parametrically after mathematical transformation of original data.