vitamin d status and its relationship with thyroid function parameters in patients with hypothyroidism

Background and objectives: vitamin d is an essential secosteroid that plays a crucial role in the homeostasis of a few mineral elements, particularly calcium. since vitamin d deficiency and thyroid diseases are two important global health problems, we aimed to investigate a possible relationship of vitamin d and calcium levels with hypothyroidism in an iranian population. methods: this casecontrol study was conducted on 175 subjects with hypothyroidism (75 males and 100 females) and 175 euthyroid controls (85 males and 90 females) who were referred to a laboratory in gorgan, iran. serum levels of 25hydroxyvitamin d, calcium, thyroidstimulating hormone (tsh), free triiodothyronine (free t3) and thyroxine (total t4) were measured in all participants. results: vitamin d and calcium were significantly lower in patients with hypothyroidism (p<0.0001). free t3 and calcium levels differed significantly among hypothyroid patients based on their vitamin d status (p<0.0001), but vitamin d levels were within sufficient range in all groups. moreover, there was a positive correlation between free t3 with vitamin d (r= 0.337, p<0.0001) and calcium (r= 0.361, p<0.0001) levels. conclusions: our results suggest that there may be a relationship between decreased vitamin d levels and thyroid function parameters. keywords: vitamin d deficiency, hypocalcemia, hypothyroidism, thyrotropin, thyroxine.