Objective: Vitamin D is an immune-modulator that may play a role in thyroid related autoimmunity. But the relation between Vitamin D and Graves disease (GD) is not well defined yet. The aim of this study was to investigate the association of 25-hydroxy-vitamin D (25[OH]D) levels and TSH receptor antibody (TRab) levels in GD.
Design: A total of 429 GD patients were analyzed retrospectively. 122 of 429 patients had vitamin D levels were enrolled in this study. The levels of 25(OH)D and TRAb were examined. Vitamin D deficiency was defined as a 25(OH)D below 20 ng/ml and insufficiency as a 25(OH) D of 2029 ng/ml. Normal range was accepted as 30 ng/ml and above. TRAb negativity was defined as 013 U/l and positivity was defined as 14 U/l and above.
Results: Among 122 patients mean age was 42.9±14 years. TRAb seropositivy was found in 69.7% (n=85). TRAb titres median was 16 U/l (minimum: 0- maximum: 295 U/l). Vitamin D deficiency was detected in 83.6% (102/122) of the patients. Vitamin D insufficiency was found in 11.5% (14/122) of the patients. Normal vitamin D levels were found in 4.9% (6/122) of the patients. Vitamin D deficiency was higher in TRAb-positive GD patients than TRAb-negative patients (respectively 75.5% (77/102) vs 24.5% (25/102) beside according to vitamin D insuffiency there was no difference between TRAb-positive and negative GD patients. There was also found a significant negative correlation between TRAb titres and vitamin D levels.
Conclusion: Low vitamin D status is associated with increased TRAb seropositivity in GD. Further research is necessary to fully elucidate the importance of vitamin D in the case of GD.