A biobank for studies of normal variability of biomarkers

Abstract

Introduction: Biomarkers of exposure or biomarkers of effects are often used in occupational health surveillance and in epidemiological research. For most biomarkers there is, however, limited information about normal day-to-day variability within individuals. For urinary biomarkers there may be diurnal variability making it important to fix the time of day the sampling is performed, but again there is very limited information in the literature about diurnal variability. Our aim was to establish a “variability biobank” of healthy individuals to make it possible for us and other researchers to examine normal variability of various biomarkers. Methods: Blood and spot urine samples were collected from 60 healthy non-smoking study participants 18-65 years of age (29 men and 31 women; no diabetes, hypertension, or kidney disease). The spot urine samples were collected during two 24h periods about one week apart, and the study participants were instructed to urinate at six fixed times (first morning void, 9:30, 12:00, 14:30, 17:30, and 22:00). The samples were transferred to Minisorb tubes (NUNC) and kept at 4°C until analysis of proteins (Albumin and Alpha-1-microglobulin), creatinine and density within 3 days of collection. Blood samples were collected twice, one in each week. Aliquots of urine and blood (blood, plasma and erythrocytes) are stored frozen (-80°C). Results: The biobank (more than 20 000 aliquots) is now open for researchers interested in examining normal variability of their favorite biomarker(s). Conclusion: The biobank is especially suitable for analysis of diurnal variation in urine biomarkers (12 samples per subject), but could also be used for analyses of variability in biomarker concentrations in blood, plasma or red cells. Variability in certain biomarkers using a previous, smaller biobank have been published for cadmium and proteins (Akerstrom et al., JEESE 2014), and 8-oxodG (Barregard et al., ARS 2013).