title: Vitamin D supplementation has minor effects on parathyroid hormone and bone turnover markers in vitamin D-deficient bedridden older patients.
abstract: OBJECTIVE
  to evaluate the effects of vitamin D supplementation on parathyroid function and bone turnover in aged, chronically immobile patients.
  
  
  METHODS
  a randomised double-blind controlled trial.
  
  
  METHODS
  two hundred and eighteen long-term inpatients aged over 65 years.
  
  
  METHODS
  the patients were randomised into treatment groups of I-III, each receiving 0 IU, 400 IU and 1200 IU cholecalciferol per day, respectively. In case of inadequate consumption of dairy products, patients received a daily calcium substitution of 500 mg.
  
  
  METHODS
  plasma concentrations of 25-hydroxyvitamin D (25-OHD), intact parathyroid hormone (PTH), amino-terminal propeptide of type I procollagen (PINP), a marker of bone formation, and carboxy-terminal telopeptide of type I collagen (ICTP), a marker of bone resorption, were measured at baseline and after 6 months.
  
  
  RESULTS
  the patients (age 84.5 years) were chronically bedridden. The baseline 25-OHD was low (23 nmol/l), correlated inversely with PINP, and tended to associate inversely with PTH. The prevalence of vitamin D deficiency (VDD) (25-OHD < 50 nmol/l) was 98% and PTH was elevated in 23% of the patients. Vitamin D supplementation significantly increased 25-OHD concentrations (124% group II, 204% group III) and decreased PTH (-7% group II, -8% group III). PINP tended to decrease, but ICTP tended to increase, and only their ratio decreased significantly. The tendency of ICTP to increase was inconsistent. Changes in 25-OHD correlated inversely with those in PTH and PINP.
  
  
  CONCLUSIONS
  vitamin D supplementation has minor effects on PTH and bone turnover in chronically immobilised aged patients with VDD. Further comparative studies and meta-analyses are warranted to elucidate the confounding effects of different mobility levels on the benefits of vitamin D supplementation in patients with differing baseline PTH levels.
authors.affiliation: Clinics of Internal Medicine and Geriatrics, Helsinki University Central Hospital, Helsinki, Finland, POB 340, FI-00290 HUS. mikko.bjorkman@helsinki.fi
authors.forename: Mikko
authors.initials: M
authors.lastname: Björkman
authors.forename: Antti
authors.initials: A
authors.lastname: Sorva
authors.forename: Juha
authors.initials: J
authors.lastname: Risteli
authors.forename: Reijo
authors.initials: R
authors.lastname: Tilvis
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001510:Bed Rest; D015519:Bone Density / Q000187:drug effects*; D002118:Calcium / Q000008:administration & dosage / Q000097:blood; D002762:Cholecalciferol / Q000008:administration & dosage*; D024042:Collagen Type I; D004305:Dose-Response Relationship, Drug; D004311:Double-Blind Method; D004359:Drug Therapy, Combination; D005260:Female; D006801:Humans; D008134:Long-Term Care; D008297:Male; D010281:Parathyroid Hormone / Q000097:blood*; D010446:Peptide Fragments / Q000097:blood*; D010455:Peptides; D011347:Procollagen / Q000097:blood*; D012016:Reference Values; D016896:Treatment Outcome; D014807:Vitamin D / Q000031:analogs & derivatives / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood*
chemical_list: D024042:Collagen Type I; D010281:Parathyroid Hormone; D010446:Peptide Fragments; D010455:Peptides; D011347:Procollagen; C052929:collagen type I trimeric cross-linked peptide; C047202:procollagen Type I N-terminal peptide; D014807:Vitamin D; D002762:Cholecalciferol; C104450:25-hydroxyvitamin D; D002118:Calcium