title: 25(OH)D Serum levels decline with age earlier in women than in men and less efficiently prevent compensatory hyperparathyroidism in older adults.
abstract: BACKGROUND
  Although a host of factors are known to influence 25-hydroxyvitamin D [25(OH)D] serum levels, few studies addressed the distinctive sex-specific influence of aging, and the age-specific relationship of parathyroid hormone (PTH) with 25(OH)D. The aims of this research were to evaluate changes of 25(OH)D and PTH levels with age in a large population-based sample of men and women and to test the hypothesis that 25(OH)D serum concentrations needed to offset age-associated hyperparathyroidism are significantly higher in older than in younger persons.
  
  
  METHODS
  In 1107 participants of the InCHIANTI (Invecchiare in Chianti, i.e., Aging in the Chianti area) study, we collected information on dietary intake, daylight exposure, and disability, and measured renal function and serum 25(OH)D and PTH.
  
  
  RESULTS
  In women, the age-related decline of 25(OH)D was already evident shortly after age 50, whereas in men it started only after age 70 and was substantially less steep. Age, daylight exposure, winter season, and disability were independent predictors of low 25(OH)D levels. For any given level of 25(OH)D, PTH levels were progressively and consistently higher in older than in younger participants.
  
  
  CONCLUSIONS
  These findings suggest that the age-associated fall of serum 25(OH)D starts earlier in women than in men and that higher levels of 25(OH)D are required in older compared to younger persons to avoid the age-associated compensatory hyperparathyroidism.
authors.affiliation: Gerontology and Geriatrics, University of Perugia, Policlinico Monteluce, Via Brunamonti, 06122 Perugia, Italy. dariomaggio1@tin.it
authors.forename: Dario
authors.initials: D
authors.lastname: Maggio
authors.forename: Antonio
authors.initials: A
authors.lastname: Cherubini
authors.forename: Fulvio
authors.initials: F
authors.lastname: Lauretani
authors.forename: Roberto Cosimo
authors.initials: RC
authors.lastname: Russo
authors.forename: Benedetta
authors.initials: B
authors.lastname: Bartali
authors.forename: Marco
authors.initials: M
authors.lastname: Pierandrei
authors.forename: Carmelinda
authors.initials: C
authors.lastname: Ruggiero
authors.forename: Maria Carmela
authors.initials: MC
authors.lastname: Macchiarulo
authors.forename: Ruben
authors.initials: R
authors.lastname: Giorgino
authors.forename: Salvatore
authors.initials: S
authors.lastname: Minisola
authors.forename: Luigi
authors.initials: L
authors.lastname: Ferrucci
mesh_terms: D005260:Female; D006801:Humans; D006961:Hyperparathyroidism / Q000517:prevention & control*; D008297:Male; D012680:Sensitivity and Specificity; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood
chemical_list: D014807:Vitamin D; C104450:25-hydroxyvitamin D