title: Hypovitaminosis D in healthy children in Central Thailand: prevalence and risk factors.
abstract: BACKGROUND
  There are limited data regarding the prevalence and risk factors relating to hypovitaminosis D in children of Thailand, a tropical country with abundant sunlight. The objective of this study was to assess the prevalence of hypovitaminosis D and examine factors associated with hypovitaminosis D in school-aged children in Bangkok, Thailand - a centrally located capital city.
  
  
  METHODS
  This cross-sectional study evaluated 159 healthy children (33.3% boys and 66.7% girls), aged 6 to 12 years, in Bangkok, Thailand (located at 13.45°N). Fasting plasma samples were examined for total 25-hydroxyvitamin D [25(OH)D] using electrochemiluminescence immunoassay. Demographic characteristics (age, sex, household income), past medical history (birth weight, allergic diseases, hospitalization), amount of sun exposure, anthropometric data, and selected biochemical tests were used to investigate for factors associated with hypovitaminosis D.
  
  
  RESULTS
  Overall, the mean ± SD level of plasma 25(OH)D was 64.0 ± 15.1 nmol/L. Hypovitaminosis D (< 75 nmol/L) was presented in 79.2% of subjects. Of these, the prevalence of vitamin D insufficiency and vitamin D deficiency were 59.7% and 19.5%, respectively. In univariate analysis, children with hypovitaminosis D (< 75 nmol/L) had a higher mean body mass index (BMI) percentile than the vitamin D-sufficient group (56.7 ± 33.9 vs. 42.6 ± 36.0; P-value = 0.04). Plasma PTH levels in the children with hypovitaminosis D were significantly higher than in the children with normal levels of vitamin D (4.34 ± 1.38 vs 3.78 ± 1.25 pmol/L; P-value = 0.04). In multivariate analysis, high BMI percentile and high PTH concentration were the parameters associated with 25(OH)D level < 75 nmol/L.
  
  
  CONCLUSIONS
  The prevalence of hypovitaminosis D in healthy Thai children is very high, despite their exposure to sunlight, and that prevalence increases in children with a high BMI percentile. As a result, a formal recommendation for vitamin D supplementation in Thai children should be considered.
authors.affiliation: Department of Clinical Pathology, Faculty of Medicine Siriraj Hospital, Mahidol University, 2 Wang Lang Road, Bangkok Noi, Bangkok, 10700, Thailand. kanit.ree@mahidol.ac.th.
authors.forename: Kanit
authors.initials: K
authors.lastname: Reesukumal
authors.affiliation: Department of Clinical Pathology, Faculty of Medicine Siriraj Hospital, Mahidol University, 2 Wang Lang Road, Bangkok Noi, Bangkok, 10700, Thailand. Kotchamol@gmail.com.
authors.forename: Kotchamol
authors.initials: K
authors.lastname: Manonukul
authors.affiliation: Department of Pediatrics, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand. jirapongo@yahoo.com.
authors.forename: Orathai
authors.initials: O
authors.lastname: Jirapongsananuruk
authors.affiliation: Department of Pediatrics, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand. Bobo_si111@hotmail.com.
authors.forename: Wijittra
authors.initials: W
authors.lastname: Krobtrakulchai
authors.affiliation: Department of Clinical Pathology, Faculty of Medicine Siriraj Hospital, Mahidol University, 2 Wang Lang Road, Bangkok Noi, Bangkok, 10700, Thailand. Sithikan@outlook.com.
authors.forename: Sithikan
authors.initials: S
authors.lastname: Hanyongyuth
authors.affiliation: Department of Pharmacology, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand. somruedee.cha@mahidol.ac.th.
authors.forename: Somruedee
authors.initials: S
authors.lastname: Chatsiricharoenkul
authors.affiliation: Department of Clinical Pathology, Faculty of Medicine Siriraj Hospital, Mahidol University, 2 Wang Lang Road, Bangkok Noi, Bangkok, 10700, Thailand. busadee.pra@mahidol.ac.th.
authors.forename: Busadee
authors.initials: B
authors.lastname: Pratumvinit
mesh_terms: D000367:Age Factors; D015992:Body Mass Index; D001837:Body Weights and Measures; D002648:Child; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D008297:Male; D015995:Prevalence; D012307:Risk Factors; D012737:Sex Factors; D012959:Socioeconomic Factors; D013472:Sunlight; D013785:Thailand / Q000453:epidemiology; D014807:Vitamin D / Q000031:analogs & derivatives / Q000097:blood; D014808:Vitamin D Deficiency / Q000453:epidemiology*
chemical_list: D014807:Vitamin D; C104450:25-hydroxyvitamin D