title: Low serum vitamin D is associated with anti-thyroid peroxidase antibody in autoimmune thyroiditis.
abstract: OBJECTIVE
  The association between autoimmune thyroid diseases (AITDs) and vitamin D deficiency is controversial. We aimed to evaluate the relationship between serum 25-hydroxy-vitamin D3 [25(OH)D3] and anti-thyroid antibody levels.
  
  
  METHODS
  25(OH)D3, anti-thyroid antibodies, and thyroid function measured in 304 patients who visited the endocrinology clinic were analyzed. The patients were subgrouped into the AITDs or non-AITDs category according to the presence or absence of anti-thyroid antibodies. The relationship between anti-thyroid peroxidase antibody (TPOAb) and 25(OH)D3 was evaluated.
  
  
  RESULTS
  The patients with elevated anti-thyroid antibodies had lower levels of serum 25(OH)D3 than those who did not (12.6±5.5 ng/mL vs. 14.5±7.3 ng/mL, respectively, p<0.001). Importantly, after adjusting for age, sex, and body mass index, a negative correlation (r=-0.252, p<0.001) was recognized between 25(OH)D3 and TPOAb levels in the AITDs group, but this correlation did not exist in the non-AITDs group (r=0.117, p=0.127). 25(OH)D3 level was confirmed as an independent factor after adjusting for co-factors that may affect the presence of TPOAb in the AITDs group.
  
  
  CONCLUSIONS
  25(OH)D3 level is an independent factor affecting the presence of TPOAb in AITDs. The causal effect of 25(OH)D3 deficiency to AITDs is to be elucidated.
authors.affiliation: Division of Endocrinology, Department of Internal Medicine, Yonsei University College of Medicine, 50-1 Yonsei-ro, Seodaemun-gu, Seoul 120-752, Korea. ejlee423@yuhs.ac.
authors.forename: Dong Yeob
authors.initials: DY
authors.lastname: Shin
authors.forename: Kwang Joon
authors.initials: KJ
authors.lastname: Kim
authors.forename: Daham
authors.initials: D
authors.lastname: Kim
authors.forename: Sena
authors.initials: S
authors.lastname: Hwang
authors.forename: Eun Jig
authors.initials: EJ
authors.lastname: Lee
mesh_terms: D000328:Adult; D000906:Antibodies / Q000097:blood; D015992:Body Mass Index; D002112:Calcifediol / Q000097:blood; D005260:Female; D006801:Humans; D007453:Iodide Peroxidase / Q000276:immunology*; D008297:Male; D008875:Middle Aged; D012044:Regression Analysis; D012189:Retrospective Studies; D013960:Thyroid Function Tests; D013967:Thyroiditis, Autoimmune / Q000097:blood* / Q000000981:diagnostic imaging / Q000276:immunology*; D014463:Ultrasonography; D014807:Vitamin D / Q000097:blood*
chemical_list: D000906:Antibodies; D014807:Vitamin D; D007453:Iodide Peroxidase; D002112:Calcifediol
keywords: Vitamin D deficiency; anti-thyroid peroxidase antibody; autoimmune thyroiditis