Reference intervals for holotranscobalamin and total vitamin B12 in 6–12-year-old children in Norway: the Health Oriented Pedagogical Project (HOPP)​Martin Frank Strand Helle Borgstrøm Hager Per Morten Fredriksen Morten Lindberg a School of Health Sciences, Kristiania University College, Oslo, Norwayb Department of Medical Biochemistry, Vestfold Hospital Trust, Tønsberg, Norwayc Faculty of Applied Ecology, Agricultural Sciences and Biotechnology, Inland Norway University of Applied Sciences, Hamar, Norwayd Faculty of Health, Welfare, and Organization, Østfold University College, Fredrikstad, Norwayon March 14, 2025 at 6:01 am