Vitamin D status and thyroid autoimmunity in Korean pregnant women.

OBJECTIVE: There is increasing interest in the role of vitamin D (vitD) during pregnancy. We prospectively evaluated the vitD status in Korean pregnant women and evaluated the levels of vitD according to thyroid-specific autoimmunity during pregnancy.

METHODS: We included pregnant 531 women who visited for prenatal care and 238 age-matched, non-pregnant women as a control population. The levels of thyrotropin, FT4, thyroid peroxidase (TPO), thyroglobulin (Tg) antibody (Ab) and 25-hydroxy vitamin D [25(OH)D] were measured by electrochemiluminescence immunoassays.

RESULTS: The mean levels of 25(OH)D at trimester 1, 2 and 3 were 13.6, 15.6 and 19.3 ng/mL, respectively; and the prevalence of vitD insufficiency was 83.6%, 75.1% and 55.9%, respectively. The mean 25(OH)D levels were not significantly different between Tg and TPO Ab-positive and negative pregnant women (14.9 versus 16.1, and 14.9 versus 16.1 ng/mL, respectively).

CONCLUSIONS: vitD insufficiency was exceptionally high, especially in the first trimester, in Korean pregnant women. The mean 25(OH)D levels were not significantly different according to autoimmunity. Further studies on this relationship could provide important information to assess the vitD status in patients with thyroid autoimmunity during pregnancy.