Affiliation: | 1. Oslo University Hospital, Department of Paediatric Medicine, Oslo, Norway;2. University of Oslo, Department of Nutrition, Institute of Basic Medical Sciences, Faculty of Medicine, Oslo, Norway;3. Oslo University Hospital, Department of Medical Biochemistry, Oslo, Norway;4. University of Bergen, Department of Clinical Science, Bergen, Norway;5. Norwegian Institute of Public Health, Department of Health Registries, Bergen, Norway |