title: Seasonal variation in 25-hydroxyvitamin D and parathyroid hormone concentrations in healthy elderly people.
abstract: Seasonal variation in serum 25-hydroxyvitamin D and parathyroid hormone concentration was examined longitudinally in 96 community-dwelling men and women aged 65-74 years. Mean 25-hydroxyvitamin D concentration was lowest in winter (22.7 mmol/l) and highest in summer (35.4 mmol/l); mean parathyroid hormone concentration was highest in winter (3.55 pmol/l) and lowest in summer (3.24 pmol/l): these seasonal variations were highly significant (p < 0.0001). Parathyroid hormone concentrations were inversely related to 25-hydroxyvitamin D concentrations (p < 0.0001). Seasonal variation of 25-hydroxyvitamin D and parathyroid hormone concentration is marked in older healthy adults in Britain. Even in summer, mean 25-hydroxyvitamin D concentrations are low; maintaining more optimal vitamin D levels in the general population may have clinical and public health benefits.
authors.affiliation: Clinical Gerontology Unit, University of Cambridge, Addenbrooke's Hospital.
authors.forename: V
authors.initials: V
authors.lastname: Hegarty
authors.forename: P
authors.initials: P
authors.lastname: Woodhouse
authors.forename: K T
authors.initials: KT
authors.lastname: Khaw
mesh_terms: D000368:Aged; D000375:Aging / Q000097:blood*; D002118:Calcium / Q000097:blood; D005260:Female; D015577:Geriatric Assessment; D006801:Humans; D008297:Male; D010281:Parathyroid Hormone / Q000097:blood*; D012016:Reference Values; D012621:Seasons; D006113:United Kingdom; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood
chemical_list: D010281:Parathyroid Hormone; D014807:Vitamin D; C104450:25-hydroxyvitamin D; D002118:Calcium