low vitamin D associated with increased autoimmune thyroid TPO antibodies in women. This association was found in pre menopause women, but not post menopause women.
high prevalence of thyroid antibodies, TPO, in women with PCOS. This does not prove cause and effect, merely an association. Both are inflammation driven.
elevated autoimmune markers against the thyroid and an elevated TSH are both independent risk factors for thyroid malignancy in those with thyroid nodules.