title: Vitamin D Insufficiency and Its Association with Biochemical and Anthropometric Variables of Young Children in Rural Southwestern China.
abstract: BACKGROUND
  With recognition of the important roles of Vitamin D (VitD) in various physiological processes, increasing attention has been drawn to the status of VitD in early life. However, the VitD status of young children and the related factors in rural areas of Southwestern China remain unclear. This study aimed to explore VitD status and its seasonal variation in 18-month-old children living in rural Southwestern China. The association of VitD with biochemical and anthropometric variables was also investigated.
  
  
  METHODS
  A total of 177 18-month-old children in a rural area of Yunnan Province, Southwestern China, were enrolled. Serum concentrations of 25-hydroxy Vitamin D (25(OH)D) were measured through high-performance liquid chromatogram-tandem mass spectrometry. Parathyroid hormone (PTH) levels were measured with a chemiluminescence assay. Serum concentrations of calcium, phosphorus, and alkaline phosphatase (ALP) were also measured. Anthropometric data and the outdoor activity time of each participant were collected.
  
  
  RESULTS
  The serum 25(OH)D concentration was 26.61 ± 7.26 ng/ml; concentrations lower than 30 ng/ml accounted for 70.6% of the participants and concentrations lower than 20 ng/ml accounted for 16.4%. The level of serum 25(OH)D was not significantly different among four seasons (P >0.05). A positive relationship was found between 25(OH)D concentration and the time of outdoor activities (r = 0.168, P < 0.05). Serum PTH concentration was negatively correlated with 25(OH)D concentration (r = -0.163, P < 0.05). A positive relationship was found between the serum concentrations of 25(OH)D and calcium (r = 0.154, P < 0.05). No significant association was observed between 25(OH)D and ALP, phosphorus, or anthropometric variables.
  
  
  CONCLUSIONS
  The prevalence of VitD insufficiency is high among young children in the rural Southwestern China regardless of the seasons. VitD supplementation is still essential to maintain VitD sufficiency for children living in rural area.
authors.affiliation: Department of Children and Adolescents Health Care, Xin Hua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai 200092; MOE-Shanghai Key Laboratory of Children's Environmental Health, Shanghai Institute for Pediatric Research, Xin Hua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai 200092, China.
authors.forename: Shan-Shan
authors.initials: SS
authors.lastname: Geng
authors.affiliation: Department of Children and Adolescents Health Care, Xin Hua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai 200092; MOE-Shanghai Key Laboratory of Children's Environmental Health, Shanghai Institute for Pediatric Research, Xin Hua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai 200092, China.
authors.forename: Jing-Qiu
authors.initials: JQ
authors.lastname: Ma
authors.affiliation: Department of Children and Adolescents Health Care, Xin Hua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai 200092; MOE-Shanghai Key Laboratory of Children's Environmental Health, Shanghai Institute for Pediatric Research, Xin Hua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai 200092, China.
authors.forename: Shan-Shan
authors.initials: SS
authors.lastname: Liu
authors.affiliation: Department of Anesthesia, The Children's Hospital, School of Medicine, Zhejiang University School of Medicine, Hangzhou, Zhejiang 310003, China.
authors.forename: Jie
authors.initials: J
authors.lastname: Zhang
authors.affiliation: Department of Children and Adolescents Health Care, Xin Hua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai 200092; MOE-Shanghai Key Laboratory of Children's Environmental Health, Shanghai Institute for Pediatric Research, Xin Hua Hospital Affiliated to Shanghai Jiao Tong University School of Medicine, Shanghai 200092, China.
authors.forename: Xiao-Yang
authors.initials: XY
authors.lastname: Sheng
mesh_terms: D000886:Anthropometry; D002681:China; D002851:Chromatography, High Pressure Liquid; D003430:Cross-Sectional Studies; D019587:Dietary Supplements; D005260:Female; D006801:Humans; D007223:Infant; D008297:Male; D010281:Parathyroid Hormone / Q000097:blood; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood; D014808:Vitamin D Deficiency / Q000097:blood* / Q000188:drug therapy
chemical_list: D010281:Parathyroid Hormone; D014807:Vitamin D; C104450:25-hydroxyvitamin D