title: [Epidemiological study on the dimension of vitamin D deficiency in North Germany].
abstract: OBJECTIVE
  In North Germany, the recommended exposure to sunlight of 30 minutes per day to produce sufficient vitamin D is hardly achieved, in particular due to weather conditions. Moreover, lifestyle and working habits also contribute to this problem. The aim of our study was therefore to investigate the prevalence of the vitamin D deficiency in North Germany.
  
  
  METHODS
  For this purpose, 25-hydroxy vitamin D levels of over 98,000 people from North Germany during the time period 2008-2011 were retrospectively analysed based on age, gender and season. 25-vitamin D status was divided into sufficient (> 75 nmol/l) and insufficient (50 to 75 nmol/l) supply as well as vitamin D deficiency (< 50 to 25 nmol/l) and severe vitamin D deficiency (< 25 nmol/l).
  
  
  RESULTS
  An undersupply of vitamin D was evident in all age groups analysed both in women and men in North Germany. Overall, vitamin D deficiency was particularly present during the months with less sunlight: more than 30 % of the people analysed showed a severe vitamin D deficiency in the months January to April. The study also showed that 25-vitamin D tests were almost evenly distributed over the individual months of the whole year and that this analysis was requested more frequently in elderly than in younger people. However, a severe vitamin D deficiency could also be detected in 25 % of the people analysed in the adolescent and young adult age group.
  
  
  CONCLUSIONS
  Based on these results, it can be recommended to test 25-vitamin D levels once a year during the months January to April to detect a severe deficiency and to early initiate preventive supplementation.
authors.affiliation: Medizinische Klinik I, Universität zu Lübeck.
authors.forename: J
authors.initials: J
authors.lastname: Kramer
authors.affiliation: Medizinische Klinik I, Universität zu Lübeck.
authors.forename: A
authors.initials: A
authors.lastname: Diehl
authors.affiliation: Medizinische Klinik I, Universität zu Lübeck.
authors.forename: H
authors.initials: H
authors.lastname: Lehnert
mesh_terms: D000293:Adolescent; D000328:Adult; D002112:Calcifediol / Q000097:blood; D003430:Cross-Sectional Studies; D004651:Employment / Q000706:statistics & numerical data; D005260:Female; D005858:Germany; D006801:Humans; D008019:Life Style; D008297:Male; D012016:Reference Values; D012621:Seasons; D013472:Sunlight; D014807:Vitamin D / Q000031:analogs & derivatives / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood / Q000453:epidemiology* / Q000209:etiology; D014887:Weather; D055815:Young Adult
chemical_list: D014807:Vitamin D; C104450:25-hydroxyvitamin D; D002112:Calcifediol