Evaluation of vitamin D levels in patients with hyperthyroidism and hypothyroidism

Vitamin D is necessary in the prevention of many types of cancer, autoimmune, cardiovascular and infectious diseases as well as contributing to the healthy bone growth. Recently, several studies was mentioned the effect on low vitamin D levels in Graves and Hashimoto thyroiditis. It has also been shown that inflammatory cytokines affected thyroid functions. In our study, we aimed to compare and investigate the relationship between thyroid hormone and vitamin D levels in patients diagnosed subclinic and clinic hypothyroidism, hyperthyroidism at Afyon Kocatepe University Medical Faculty, Department of Endocrinology Clinic. In the study, we investigated the levels of serum vitamin D and the related parameters such as parathyroid hormone (PTH), calcium (Ca) and malondialdehyde (MDA), reduced glutathione (GSH), tumor necrosis factor-alpha (TNF-α), interferon gamma (IFN-γ), interleukin 6 (IL-6), interleukin 17 (IL-17) of patients with subclinical and clinical hypothyroidism and hyperthyroidism and showed the relation between the parameters. Patients were divided into 4 groups such as subclinical and clinical hypothyroidism, subclinical and clinical hyperthyroidism including 15, 15, 15 and 16 patients, respectively in accordance with free T3 (fT3), free T4 (fT4) and TSH levels. In our study, 29 patients were selected as the control group which were nonsmoker, nonalcholic, did not use any drugs that may affect the thyroid metabolism, oxidative stress and without any chronic diseases such as hypertension, diabetes, hyperlipidemia. There was no statistically a significant relationship between serum 25 (OH) vitamin D and parameters with related such as PTH and Ca levels in patients with subclinical, clinical hypothyroidism and control group. It was shown a significant reduction in GSH levels between subclinical and clinical hypothyroidism group compared with the control group (p <0.01; p <0.001, respectively). It was observed a significant increase in the TSH, IL-6, IL-17 and MDA levels (p<0.001), a significant decrease in the IFN-γ levels (p<0.001) in subclinical hypothyroidism group at comparison with the control group. Whereas, a significant increase was seen in TSH, IL-6 and MDA levels (p <0.001; p <0.001; p <0.01, respectively) and a significant reduction were also seen in fT3, fT4 and IL-17 levels in clinical hypothyroidism group (p<0.01; p<0.001; p<0.001; respectively). There was no a statisticant change in levels of vitamin D, PTH and Ca levels in patients with subclinical and clinical hyperthyroidism groups compared to the control group. It was determined a significant reduction in TSH, IFN-γ, IL-17 and GSH levels (p<0.001; p<0.01; p<0.001; p<0.001, respectively), as well as a significant increase was detected in fT4 and IL-6 and MDA levels (p<0.01; p<0.001; p<0.001 respectively), according to the control group in subclinical hyperthyroidism group. A significant decrease was observed in TSH, IL-17 and GSH levels in clinical hyperthyroidism group (p<0.001), but the levels of fT3, fT4, TNF-α, IL-6 and MDA increased (p<0.001; p<0.001; p<0.01; p<0.001; p<0.001, respectively). As a result, there was not significant relationship in levels of 25-OH vitamin D, PTH and Ca levels, but MDA levels significantly increased and GSH levels decreased that caused oxidative stress in groups of subclinical, clinical hypothyroidism and subclinical, clinical hyperthyroidism. The different results obtained in serum levels of inflammatory cytokines was showed that need for further studies in this regard.