Urinary creatininewas determined using Vitros creatinine slides
and Vitros Chemistry Products calibrator kits on a Vitros 250
chemistry system (Ortho-Clinical Diagnostic System Inc., Rochester,
NY, USA). Intra- and inter-assay CVs were below5%. Equipmentwas
calibrated according to the manufacturers’ instructions and
external standards including standards from the Danish Institute
for External Quality Assurance for Laboratories in Health Care
(DEKS). Dilution and recovery tests were satisfactory. In all assay
runs, samples from the various subgroups of the study population
were included in random order.