title: Tracking of serum 25-hydroxyvitamin D levels during 14 years in a population-based study and during 12 months in an intervention study.
abstract: Low serum 25-hydroxyvitamin D (25(OH)D) levels are associated with risk factors for cardiovascular disease, and they also appear to predict later development of type 2 diabetes, cancer, and an increased mortality rate. These predictions are all based on a single 25(OH)D measurement, but so far there are no known reports on tracking of serum 25(OH)D levels. In the present Norwegian study, serum 25(OH)D levels were measured 1) in 2,668 subjects in the 1994 and 2008 Tromsø surveys and 2) every third month for 1 year in 94 subjects randomly assigned to placebo in a vitamin D intervention study. There was a marked seasonal variation in 25(OH)D, and, depending on the method of adjusting for season, the correlation coefficient between serum 25(OH)D measurements from 1994 and 2008 ranged from 0.42 to 0.52. In the 1-year intervention study, the correlation between baseline and 12-month values was 0.80. Apart from the effect of season, changes in weight, intake of vitamin D, and physical activity were related to change in serum 25(OH)D levels. Tracking of serum 25(OH)D appears similar to that for blood pressure and serum lipids, and it provides some support for the use of a single 25(OH)D measurement to predict future health outcomes.
authors.affiliation: Institute of Clinical Medicine, University of Tromsø, Tromsø, Norway. rolf.jorde@unn.no
authors.forename: Rolf
authors.initials: R
authors.lastname: Jorde
authors.forename: Monica
authors.initials: M
authors.lastname: Sneve
authors.forename: Moira
authors.initials: M
authors.lastname: Hutchinson
authors.forename: Nina
authors.initials: N
authors.lastname: Emaus
authors.forename: Yngve
authors.initials: Y
authors.lastname: Figenschau
authors.forename: Guri
authors.initials: G
authors.lastname: Grimnes
mesh_terms: D000368:Aged; D000704:Analysis of Variance; D016009:Chi-Square Distribution; D002762:Cholecalciferol / Q000008:administration & dosage*; D016903:Drug Monitoring / Q000379:methods*; D016021:Epidemiologic Studies; D005260:Female; D006801:Humans; D016014:Linear Models; D008137:Longitudinal Studies; D008297:Male; D008875:Middle Aged; D009664:Norway / Q000453:epidemiology; D015596:Nutrition Assessment; D011159:Population Surveillance / Q000379:methods*; D011237:Predictive Value of Tests; D012307:Risk Factors; D012621:Seasons; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood / Q000188:drug therapy / Q000453:epidemiology; D014815:Vitamins / Q000008:administration & dosage*
chemical_list: D014815:Vitamins; D014807:Vitamin D; D002762:Cholecalciferol; C104450:25-hydroxyvitamin D