Planned variation in preanalytical conditions to evaluate biospecimen stability in the National Children's Study (NCS)

Background: Preanalytical conditions encountered during collection, processing, and storage of biospecimens may influence laboratory results. The National Children's Study (NCS) is a planned prospective cohort study of 100,000 families to examine the influence of a wide variety of exposures on child health. In developing biospecimen collection, processing, and storage procedures for the NCS, we identified several analytes of different biochemical categories for which it was unclear to what extent deviations from NCS procedures could influence measurement results. Methods: A pilot study was performed to examine effects of preanalytic sample handling conditions (delays in centrifugation, freezing delays, delays in separation from cells, additive delay, and tube type) on concentrations of eight different analytes. A total of 2825 measurements were made to assess 15 unique combinations of analyte and handling conditions in blood collected from 151 women of childbearing age (≥20 individuals per handling condition). Results: The majority of analytes were stable under the conditions evaluated. However, levels of plasma interleukin-6 and serum insulin were decreased in response to sample centrifugation delays of up to 5.5 h post-collection (p<0.0001). In addition, delays in freezing centrifuged plasma samples (comparing 24, 48 and 72 h to immediate freezing) resulted in increased levels of adrenocorticotropic hormone (p=0.0014). Conclusions: Determining stability of proposed analytes in response to preanalytical conditions and handling helps to ensure high-quality specimens for study now and in the future. The results inform development of procedures, plans for measurement of analytes, and interpretation of laboratory results.