title: Public health implications of standardized 25-hydroxyvitamin D levels: a decrease in the prevalence of vitamin D deficiency among older women in Germany.
abstract: OBJECTIVE
  To compare the public health implications of using unstandardized immunoassay measurements of serum 25-hydroxyvitamin D [25(OH)D] concentrations versus using measurements standardized by liquid chromatography tandem-mass spectrometry (LC-MS/MS) when assessing the prevalence of 25(OH)D insufficiency and deficiency in various subgroups of individuals.
  
  
  METHODS
  We standardized immunoassay-based measurements of 25(OH)D with LC-MS/MS in a population-based sample of 5386 women aged 50-74 recruited in 2000-2002 in Germany. We used multivariate regression to assess 25(OH)D determinants and the association of vitamin D deficiency with health status.
  
  
  RESULTS
  Prevalences of 25(OH)D levels <50 nmol/L (insufficiency) and <30 nmol/L (deficiency) decreased considerably by standardization. The decrease in vitamin D deficiency (from 64.4% to 17.9%) was particularly strong in March-May among women aged ≥ 65. Independent of season of blood draw and standardization, women ≥ 70 years, obese, or currently smoking had an increased risk of having 25(OH)D levels <30 nmol/L.
  
  
  CONCLUSIONS
  The proportion of older women with vitamin D deficiency in Germany is much lower than previously reported, but prevalence of vitamin D insufficiency is high. Standardization of 25(OH)D values by immunoassay methods to LC-MS/MS equivalent values or direct measurement by LC-MS/MS is indispensable in drawing valid conclusions about the health implications of vitamin D deficiency or insufficiency.
authors: German Cancer Research Center (DKFZ), Division of Clinical Epidemiology and Aging Research, Im Neuenheimer Feld 581, 69120 Heidelberg, Germany. l.perna@dkfz-heidelberg.de
authors: Laura
authors: L
authors: Perna
authors: Ulrike
authors: U
authors: Haug
authors: Ben
authors: B
authors: Schöttker
authors: Heiko
authors: H
authors: Müller
authors: Elke
authors: E
authors: Raum
authors: Eugène H J M
authors: EH
authors: Jansen
authors: Hermann
authors: H
authors: Brenner
mesh_terms: D000368:Aged; D000375:Aging / Q000097:blood; D002853:Chromatography, Liquid; D005260:Female; D005858:Germany / Q000453:epidemiology; D006801:Humans; D008875:Middle Aged; D015995:Prevalence; D011634:Public Health; D012044:Regression Analysis; D012189:Retrospective Studies; D053719:Tandem Mass Spectrometry; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood / Q000592:standards; D014808:Vitamin D Deficiency / Q000097:blood* / Q000453:epidemiology
chemical_list: D014807:Vitamin D; C104450:25-hydroxyvitamin D