More on Premetrologic Variation

Generally, clinicians and laboratorians consider that premetrologic variation is negligible if all premetrologic sources of variation are standardized (1), but it has been demonstrated that in many instances this is not so (2)(3)(4). The aim of this study is to quantify the premetrologic variation associated with 33 biochemical quantities frequently measured in clinical laboratories.All premetrologic procedures (sampling, transport, centrifugation, handling, and distribution of the samples) were done according to the working instructions of our laboratory. We recruited 38 healthy volunteers. Each individual had two immediately consecutive withdrawals, one from each arm at random, done by two different phlebotomists; the pair of phlebotomists was different for each individual. The samples were obtained from the antecubital vein, using evacuated tubes without additives but with a gel barrier as serum separator (Vacutainer®; product no. 368510; Becton Dickinson). …