title: Demographic, dietary, and biochemical determinants of vitamin D status in inner-city children.
abstract: BACKGROUND
  Reports of clinical rickets are particularly evident in minority infants and children, but only limited analyses of vitamin D are available in this demographic group.
  
  
  OBJECTIVE
  We sought to characterize circulating 25-hydroxyvitamin D [25(OH)D], 1,25-dihydroxyvitamin D [1,25(OH)(2)D], and their determinants, including circulating parathyroid hormone (PTH), total alkaline phosphatase activity (ALP), calcium, and phosphorus, in minority infants and children.
  
  
  METHODS
  We obtained demographic information and blood samples for measurement of PTH, ALP, 25(OH)D, and 1,25(OH)(2)D in >750 6-mo- to 3-y-old children. Dietary intake data were obtained and analyzed.
  
  
  RESULTS
  The mean (±SD) 25(OH)D concentration was 66 ± 22 nmol/L (26.3 ± 8.7 ng/dL). A total of 15% of children had 25(OH)D concentrations less than the recommended target threshold of 50 nmol/L. Combined elevations of PTH and ALP occurred in only 2.5% of children. Determinants of 25(OH)D included vitamin D intake, age (decreasing with age), skin type (greater concentrations in lighter-skinned children than in darker-skinned children), formula use (higher intakes), season (greater concentrations in the summer and fall than in the winter and spring), and, inversely, PTH. The mean 1,25(OH)(2)D concentration was 158 ± 58 pmol/L (60.6 ± 22.5 pg/mL), which was consistent with a reference range of 41-274 pmol/L or 15.7-105.5 pg/mL. Determinants for 1,25(OH)(2)D were age (decreasing with age), sex (greater concentrations in girls than in boys), skin type (greater concentrations in lighter-skinned children than in darker-skinned children), and, inversely, serum calcium and phosphorus.
  
  
  CONCLUSIONS
  Although 15% of subjects were vitamin D insufficient, only 2.5% of subjects had elevations of both PTH and ALP. The greater 25(OH)D concentrations observed with formula use confirm that dietary vitamin D fortification is effective in this demographic group. Circulating 1,25(OH)(2)D is higher in infants than in older children and adults and, in contrast to 25(OH)D, is not directly correlated with nutrient intakes.
authors.affiliation: Department of Pediatrics, Yale University School of Medicine, New Haven, CT 06520-8064, USA. thomas.carpenter@yale.edu
authors.forename: Thomas O
authors.initials: TO
authors.lastname: Carpenter
authors.forename: Francisca
authors.initials: F
authors.lastname: Herreros
authors.forename: Jane H
authors.initials: JH
authors.lastname: Zhang
authors.forename: Bruce K
authors.initials: BK
authors.lastname: Ellis
authors.forename: Christine
authors.initials: C
authors.lastname: Simpson
authors.forename: Esther
authors.initials: E
authors.lastname: Torrealba-Fox
authors.forename: Grace J
authors.initials: GJ
authors.lastname: Kim
authors.forename: Mary
authors.initials: M
authors.lastname: Savoye
authors.forename: Nancy A
authors.initials: NA
authors.lastname: Held
authors.forename: David E C
authors.initials: DE
authors.lastname: Cole
mesh_terms: D000367:Age Factors; D000469:Alkaline Phosphatase / Q000097:blood*; D002118:Calcium / Q000097:blood; D002391:Catchment Area, Health; D002675:Child, Preschool; D004032:Diet / Q000208:ethnology; D005260:Female; D006801:Humans; D006961:Hyperparathyroidism / Q000208:ethnology; D007223:Infant; D008297:Male; D008913:Minority Groups; D010281:Parathyroid Hormone / Q000097:blood*; D010758:Phosphorus / Q000097:blood; D015995:Prevalence; D012016:Reference Values; D012621:Seasons; D012737:Sex Factors; D012880:Skin Pigmentation / Q000502:physiology; D014505:Urban Population; D014807:Vitamin D / Q000008:administration & dosage / Q000031:analogs & derivatives* / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood / Q000208:ethnology*; D014815:Vitamins / Q000008:administration & dosage / Q000097:blood*
chemical_list: D010281:Parathyroid Hormone; D014815:Vitamins; D014807:Vitamin D; D010758:Phosphorus; C097949:1,25-dihydroxyvitamin D; C104450:25-hydroxyvitamin D; D000469:Alkaline Phosphatase; D002118:Calcium