title: Vitamin D deficiency and lifestyle risk factors in a Norwegian adolescent population.
abstract: OBJECTIVE
  The aim was to study vitamin D status in a healthy adolescent Norwegian population at 69°N.
  
  
  METHODS
  The data presented come from The Tromsø Study: Fit Futures, during the school year 2010/2011 (not including the summer months), where 1,038 (92% of those invited) participated. Physical examinations, questionnaires and blood samples were collected, and serum 25-hydroxyvitamin D (25(OH)D) were analyzed using LC-MS/MS.
  
  
  RESULTS
  RESULTS are presented from 475 boys and 415 girls (15-18 years old) with available blood samples. A total of 60.2% had vitamin D deficiency or insufficiency (serum 25(OH)D <50 nmol/l), 16.5% were deficient (<25 nmol/l) and 1.6% had severe vitamin D deficiency (<12.5 nmol/l). Only 12.4% had levels >75 nmol/l. A significant gender difference with a mean (SD) serum 25(OH)D level of 40.5 (20.5) nmol/l in boys and 54.2 (23.2) nmol/l in girls (p <0.01) was present. Furthermore, 51.3% of girls had levels >50 nmol/l in comparison to 29.7% of boys (p <0.01). There was an inverse correlation between parathyroid hormone levels and 25(OH)D, rs= -0.30 (p<0.01). Explanatory factors that were significantly associated with serum 25(OH)D levels in multivariate models were use of snuff, consumption of vitamin D fortified milk, cod liver oil and vitamin/mineral supplements, physical activity, sunbathing holiday and use of solarium in boys, and vitamin/mineral supplements, physical activity, sunbathing holiday and use of solarium in girls .
  
  
  CONCLUSIONS
  Vitamin D deficiency is prevalent during the school year among adolescents in northern Norway, particularly among boys.
authors: Tromsø Endocrine Research Group, Department of Clinical Medicine, UiT The Arctic University of Norway, Tromsø, Norway johanna.oberg@hotmail.com.
authors: Johanna
authors: J
authors: Oberg
authors: Tromsø Endocrine Research Group, Department of Clinical Medicine, UiT The Arctic University of Norway, Tromsø, Norway University Hospital of North Norway, Division of Internal Medicine, Tromsø, Norway.
authors: Rolf
authors: R
authors: Jorde
authors: Haukeland University Hospital, The Hormone Laboratory, Bergen, Norway.
authors: Bjørg
authors: B
authors: Almås
authors: Department of Health and Care Sciences, UiT The Arctic University of Norway, Tromsø, Norway.
authors: Nina
authors: N
authors: Emaus
authors: Tromsø Endocrine Research Group, Department of Clinical Medicine, UiT The Arctic University of Norway, Tromsø, Norway University Hospital of North Norway, Division of Internal Medicine, Tromsø, Norway.
authors: Guri
authors: G
authors: Grimnes
mesh_terms: D015652:25-Hydroxyvitamin D 2 / Q000097:blood*; D000293:Adolescent; D005260:Female; D006801:Humans; D008019:Life Style; D008297:Male; D009664:Norway / Q000453:epidemiology; D012307:Risk Factors; D017678:Sex Distribution; D014808:Vitamin D Deficiency / Q000453:epidemiology*
chemical_list: D015652:25-Hydroxyvitamin D 2
keywords: Adolescents; epidemiology; parathyroid hormone; population-based study; risk factors; vitamin D; vitamin D deficiency