title: Effects of different doses of oral cholecalciferol on serum 25(OH)D, PTH, calcium and bone markers during fall and winter in schoolchildren.
abstract: OBJECTIVE
  Controversies surround the actual requirements of vitamin D in adolescents. We aimed to assess the efficacy and safety of different doses of vitamin D in high schoolchildren of Taleghan (latitude 36.5°N) near Tehran.
  
  
  METHODS
  In a randomized double-blind, placebo-controlled trial, 210 subjects, aged 14-20 years, 105 boys and 105 girls were assigned to three groups; group A (n=70) received 50 000 U oral cholecalciferol monthly (equal to 1600 U per day), group B (n=70), 50 000 U bimonthly (equal to 800 U/day) and group C (n=70), placebo. The study began in November 2007 and continued until April 2008. Serum 25(OH)D, parathyroid hormone (PTH), calcium (Ca) and bone markers were measured.
  
  
  RESULTS
  At baseline, girls had significantly lower concentrations of 25(OH)D than boys (19.25±16 vs 40.5±14 nmol/l). Mean 25(OH)D increased from 32±22 to 60±27.5 and 28.25±14.5 to 45.75±24 in groups A and B, respectively (P<0.001); however, it did not change over time in group C (29±18 vs 29±17.5). Increment of mean 25(OH)D was higher in group A than in group B (P<0.01). In all groups, girls had lower concentrations of 25(OH)D than boys (P<0.001). Serum Ca increased and PTH decreased in groups A and B (P<0.001). In group A, osteocalcin (OC) and bone-specific alkaline phosphatase increased (P<0.001), but in group B only OC increased (P<0.001). Urine C telopeptide and Ca did not change in all three groups; no case of hypercalcemia was observed.
  
  
  CONCLUSIONS
  Although monthly administration of 50 000 U vitamin D(3) increased serum 25(OH)D significantly, it was apparently not enough to correct vitamin D deficiency, especially in girls.
authors.affiliation: Endocrine Research Center, Research Institute for Endocrine Sciences, Shahid Beheshti University of Medical Sciences, Tehran, Iran. ghazi@endocrine.ac.ir
authors.forename: A A
authors.initials: AA
authors.lastname: Ghazi
authors.forename: F
authors.initials: F
authors.lastname: Hosseinpanah
authors.forename: E
authors.initials: E
authors.lastname: M Ardakani
authors.forename: S
authors.initials: S
authors.lastname: Ghazi
authors.forename: M
authors.initials: M
authors.lastname: Hedayati
authors.forename: F
authors.initials: F
authors.lastname: Azizi
mesh_terms: D000284:Administration, Oral; D000293:Adolescent; D017195:Adolescent Nutritional Physiological Phenomena; D015415:Biomarkers; D015519:Bone Density; D002118:Calcium / Q000097:blood*; D002762:Cholecalciferol / Q000008:administration & dosage* / Q000494:pharmacology*; D019587:Dietary Supplements; D004311:Double-Blind Method; D005260:Female; D006801:Humans; D007492:Iran / Q000453:epidemiology; D008297:Male; D010281:Parathyroid Hormone / Q000097:blood*; D012621:Seasons; D014807:Vitamin D / Q000031:analogs & derivatives / Q000097:blood; D014808:Vitamin D Deficiency / Q000188:drug therapy / Q000453:epidemiology; D055815:Young Adult
chemical_list: D015415:Biomarkers; D010281:Parathyroid Hormone; D014807:Vitamin D; D002762:Cholecalciferol; C104450:25-hydroxyvitamin D; D002118:Calcium