title: Children with hemoglobin E/β-thalassemia have a high risk of being vitamin D deficient even if they get abundant sun exposure: a study from Thailand.
abstract: BACKGROUND
  Vitamin D is a key component in calcium homeostasis, bone mineralization and immune function, and people with a vitamin D deficiency may therefore be at higher risk of osteoporosis, osteopenia, delayed growth and fractures. Vitamin D deficiency is a known clinical complication of patients with β-thalassemia major; however, as yet there are limited data on the vitamin D status of patients with Hb E/β-thalassemia. Hb E/β-thalassemia is characterized by a wide clinical heterogeneity ranging from non-transfusion dependency to transfusion dependency. Because patients with Hb E/β-thalassemia are so clinically diverse, the prevalence of vitamin D deficiency might differ among Hb E/β-thalassemia patients.
  
  
  METHODS
  We investigated the vitamin D status of 109 children with Hb E/β-thalassemia who attended the Pediatric Hematology Clinic at the Siriraj Hospital in Bangkok, Thailand, from April 2009 to March 2010.
  
  
  RESULTS
  Forty-nine of the children were classified as transfusion-dependent (TD) and the remainder (n = 60) as non-transfusion-dependent (NTD). Only 10.1% of the children in our study had normal vitamin D levels, despite Thailand's geographic position 15° N and 100° E and climate, which provides abundant sunlight exposure and therefore efficient vitamin D synthesis. In addition, NTD children were significantly more likely to be vitamin D deficient than TD children (P = 0.01).
  
  
  CONCLUSIONS
  Our results highlight the importance of monitoring serum vitamin D levels in children with Hb E/β-thalassemia regardless of their clinical severity or the amount of sunlight they are exposed to.
authors.affiliation: Division of Pediatric Endocrinology, Department of Pediatrics, Faculty of Medicine Siriraj Hospital, Mahidol University, Bangkok, Thailand.
authors.forename: Pairunyar
authors.initials: P
authors.lastname: Nakavachara
authors.forename: Vip
authors.initials: V
authors.lastname: Viprakasit
mesh_terms: D000293:Adolescent; D001803:Blood Transfusion; D002648:Child; D002675:Child, Preschool; D005260:Female; D006446:Hemoglobin E; D006801:Humans; D008297:Male; D013785:Thailand / Q000453:epidemiology; D014807:Vitamin D / Q000097:blood*; D014808:Vitamin D Deficiency / Q000097:blood / Q000453:epidemiology / Q000209:etiology; D017086:beta-Thalassemia / Q000097:blood / Q000150:complications / Q000453:epidemiology / Q000628:therapy
chemical_list: D014807:Vitamin D; D006446:Hemoglobin E
keywords: hemoglobinopathies; thalassemia; vitamin D deficiency