Evaluation of serum vitamin D levels in elderly patients with subclinical hypothyroidism

Increasing numbers of researches have indicated the relationship between serum vitamin d level and several autoimmune diseases, because it has important roles in immune regulation. however, the role of vitamin d in the etiopathogenesis of these diseases is not well understood. similarly, the detailed mechanism of vitamin d action on thyroid hormone metabolism and autoimmune thyroid diseases is still poorly understood. it was recently reported that patients with autoimmune thyroid disease showed lower vitamin d levels. however, there are few studies dealing with vitamin d status in elderly patients with subclinical hypothyroidism. we therefore aimed to investigate vitamin d levels in elderly patients with subclinical hypothyroidism. in the present study, a total of 37 patients (>70 years old) with subclinical hypothyroidism and 40 healthy controls (>70 years old) were retrospectively analyzed. serum levels of free triiodothyronine (ft3), free thyroxine (ft4) and thyroid-stimulating hormone (tsh) were analyzed by chemiluminescence immunoassay (centaur xp, siemens healthcare diagnostics inc., tarrytown, usa). serum levels of 25-hydroxy vitamin d (25-oh d) were measured by chemiluminescence immunoassay (diasorin, liaison, italy). serum anti thyroid peroxidase (anti-tpo) and anti thyroglobulin (anti-tg) were measured using a solid-phase, enzyme-labeled, chemiluminenescent sequential immunometric assay (immulite 2000 xpi, siemens healthcare diagnostics inc., tarrytown, usa). there was no significant difference between groups in terms of age and gender distribution. serum tsh, anti-tpo and anti-tg levels in elderly patients with subclinical hypothyroidism showed higher values than healthy controls as expected. serum 25-oh d levels in elderly patients with subclinical hypothyroidism were lower than healthy controls (p<0.001). these data may suggest association between serum 25-oh d levels and subclinical hypothyroidism in elderly patients. further studies are needed to determine whether vitamin d insufficiency is a casual factor in the etiopathogenesis of subclinical hypothyroidism in elderly patients or rather a consequence of the disease.