TPO and Autoimmunity: Kivity et al. examined serum vitamin D levels in relation to anti-thyroid peroxidase (anti-TPO) and anti-thyroglobulin (anti-TG) antibodies in 92 patients with thyroid diseases (28 patients with Hashimoto’s thyroiditis, 22 patients with Graves’ disease, 42 patients without evidence for autoimmunity) and 98 age-matched healthy control subjects [31].