title: Low Vitamin D Status is Associated with Increased Thyrotropin-Receptor Antibody Titer in Graves Disease.
abstract: OBJECTIVE
  Vitamin D deficiency is reportedly linked to a variety of autoimmune diseases. However, the relationship between thyroid autoimmunity in Graves disease (GD) and vitamin D deficiency is unclear. The goal of this study was to determine whether increased thyroid hormone autoantibody titer is associated with vitamin D deficiency in GD patients.
  
  
  METHODS
  A total of 70 patients with GD and 70 matched control subjects were recruited to our study. The levels of 25-hydroxyvitamin D (25[OH]D), calcium, parathyroid hormone (PTH), free triiodothyronine (FT3), free thyroxine (FT4), thyroid-stimulating hormone (TSH), thyrotropin-receptor antibody (TRAb), thyroid-peroxidase antibody (TPOAb), and thyroglobulin antibody (TGAb) in serum collected from these patients and controls were examined.
  
  
  RESULTS
  The level of 25(OH)D in serum from TRAb-positive GD patients was significantly lower than that in serum of healthy controls or TRAb-negative patients. However, compared with control subjects, the level of PTH in serum was increased in TRAb-positive GD patients. The rate of vitamin D deficiency (defined as serum 25[OH]D <50 nmol/L) in TRAb-positive GD patients was significantly higher than in healthy controls or TRAb-negative GD patients. The level of 25(OH)D in serum was inversely correlated with TRAb titer in serum of TRAb-positive GD patients. However, our results did not show a correlation between 25(OH)D level and the levels of TPOAb, TGAb, FT3, FT4, or TSH.
  
  
  CONCLUSIONS
  Low vitamin D status is associated with increased TRAb titer in GD, suggesting a possible link between vitamin D status and increased thyroid autoimmunity in GD patients.
authors.affiliation: Institute of Metabolism and Endocrinology, The Second Xiangya Hospital, Central South University, Changsha, Hunan, China.
authors.forename: Hong
authors.initials: H
authors.lastname: Zhang
authors.affiliation: Institute of Metabolism and Endocrinology, The Second Xiangya Hospital, Central South University, Changsha, Hunan, China.
authors.forename: Lingyun
authors.initials: L
authors.lastname: Liang
authors.affiliation: Institute of Metabolism and Endocrinology, The Second Xiangya Hospital, Central South University, Changsha, Hunan, China.
authors.forename: Zhongjian
authors.initials: Z
authors.lastname: Xie
mesh_terms: D000328:Adult; D001323:Autoantibodies / Q000097:blood*; D005260:Female; D006111:Graves Disease / Q000276:immunology*; D006801:Humans; D008297:Male; D008875:Middle Aged; D011989:Receptors, Thyrotropin / Q000276:immunology*; D013974:Thyroxine / Q000097:blood; D014284:Triiodothyronine / Q000097:blood; D014807:Vitamin D / Q000031:analogs & derivatives* / Q000097:blood
chemical_list: D001323:Autoantibodies; D011989:Receptors, Thyrotropin; D014284:Triiodothyronine; D014807:Vitamin D; C104450:25-hydroxyvitamin D; D013974:Thyroxine