title: Single-dose cholecalciferol suppresses the winter increase in parathyroid hormone concentrations in healthy older men and women: a randomized trial.
abstract: A randomized double-blind controlled trial of a single oral dose of 2.5 mg (100,000 IU) cholecalciferol (vitamin D3) was conducted in the winter in 189 healthy free-living men and women aged 63-76 y. The mean baseline serum concentration for 25-hydroxyvitamin D was 34.5 nmol/L and for parathyroid hormone 3.18 pmol/L. After 5 wk, mean serum 25-hydroxyvitamin D concentrations were 60% higher in the treated than in the placebo group (P < 0.001). There was a 12% difference in parathyroid hormone concentrations in the treated compared with the placebo group (P < 0.001). No differences in serum calcium were seen. Findings suggest that 25-hydroxyvitamin D has a physiological role in the regulation of parathyroid secretion independent of serum calcium in healthy elderly people. Parathyroid concentrations rise and 25-hydroxyvitamin D concentrations decline with age. These results may have implications for the prevention of osteoporotic fractures that occur with increased frequency in winter and in elderly people.
authors.affiliation: Clinical Gerontology Unit, University of Cambridge School of Clinical Medicine, Addenbrooke's Hospital, UK.
authors.forename: K T
authors.initials: KT
authors.lastname: Khaw
authors.forename: R
authors.initials: R
authors.lastname: Scragg
authors.forename: S
authors.initials: S
authors.lastname: Murphy
mesh_terms: D000368:Aged; D002112:Calcifediol / Q000097:blood; D002762:Cholecalciferol / Q000008:administration & dosage / Q000494:pharmacology* / Q000627:therapeutic use; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D010024:Osteoporosis / Q000517:prevention & control; D010281:Parathyroid Hormone / Q000097:blood*; D012621:Seasons
chemical_list: D010281:Parathyroid Hormone; D002762:Cholecalciferol; D002112:Calcifediol