Abstract:

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.

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