title: Vitamin D production after UVB exposure - a comparison of exposed skin regions.
abstract: BACKGROUND
  Cholecalciferol is an essential steroid produced in the skin by solar ultraviolet B radiation (UVB 290-315nm). Skin production of cholecalciferol depends on factors affecting UVB flux, age and exposed skin area.
  
  
  OBJECTIVE
  Serum cholecalciferol and 25-hydroxyvitamin D3 [25(OH)D3] concentrations were measured after UVB irradiation of 3 different skin areas to compare the skin capacity to produce vitamin D in different anatomic sites in the same individuals.
  
  
  METHODS
  Ten voluntary Caucasians (skin photo type II & III, aged 48±12years (±SD)) were exposed to broadband UVB (280-320nm) between February and April. Hands and face, upper body and whole body were exposed to a suberythemic dose of UVB (median 101mJ/cm(2) (min 66, max 143)) (for 3 subsequent days 24h apart with a wash out period of about 3weeks (median 18days (min 11, max 25)) between the exposures of respective area. Serum concentrations of cholecalciferol and 25(OH)D3, were measured immediately before the first and 24h after the last dose of radiation.
  
  
  RESULTS
  There was a significantly higher increase in serum cholecalciferol after UVB exposure of the two larger skin areas compared to face and hands, but no difference in increase was found between upper body and whole body exposures.
  
  
  CONCLUSIONS
  Exposure of a larger skin area was superior to small areas and gave greater increase in both serum cholecalciferol and serum 25(OH)D3 concentrations. However, exposure of face and hands, i.e. only 5% of the body surface area, was capable of increasing serum concentrations of 25(OH)D3.
authors.affiliation: Dept of Dermatology, Sahlgrenska University Hospital, Sweden. Electronic address: Amra.Osmancevic@vgregion.se.
authors.forename: Amra
authors.initials: A
authors.lastname: Osmancevic
authors.affiliation: Dept of Dermatology, Sahlgrenska University Hospital, Sweden.
authors.forename: Katarina
authors.initials: K
authors.lastname: Sandström
authors.affiliation: Dept of Dermatology, Sahlgrenska University Hospital, Sweden.
authors.forename: Martin
authors.initials: M
authors.lastname: Gillstedt
authors.affiliation: Section for Endocrinology, Dept of Internal Medicine, Sahlgrenska University Hospital, at Sahlgrenska Academy, University of Gothenburg, Gothenburg, Sweden.
authors.forename: Kerstin
authors.initials: K
authors.lastname: Landin-Wilhelmsen
authors.affiliation: Dept of Dermatology, Sahlgrenska University Hospital, Sweden.
authors.forename: Olle
authors.initials: O
authors.lastname: Larkö
authors.affiliation: Dept of Dermatology, Sahlgrenska University Hospital, Sweden.
authors.forename: Ann-Marie
authors.initials: AM
authors.lastname: Wennberg Larkö
authors.affiliation: Boston University School of Medicine, Boston, MA 02118, USA.
authors.forename: Michael
authors.initials: M
authors.lastname: F Holick
authors.affiliation: Dept of Dermatology, Sahlgrenska University Hospital, Sweden; Dept of Dermatology, RH University Hospital, Oslo, Norway.
authors.forename: Anne-Lene
authors.initials: AL
authors.lastname: Krogstad
mesh_terms: D000328:Adult; D000368:Aged; D002112:Calcifediol / Q000096:biosynthesis* / Q000097:blood; D002762:Cholecalciferol / Q000096:biosynthesis / Q000097:blood; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012867:Skin / Q000378:metabolism* / Q000528:radiation effects*; D014466:Ultraviolet Rays
chemical_list: D002762:Cholecalciferol; D002112:Calcifediol