The effect of vitamin D on thyroid autoimmunity in euthyroid men with autoimmune thyroiditis and testosterone deficiency

Impact of Vitamin D on Immunopathology of Hashimoto's Thyroiditis: From Theory to Practice

Hashimoto's thyroiditis (HT) is a common autoimmune disease affecting the thyroid gland, characterized by lymphocytic infiltration, damage to thyroid cells, and hypothyroidism, and often requires lifetime treatment with levothyroxine. The disease has a complex etiology, with genetic and environmental factors contributing to its development. Vitamin D deficiency has been linked to a higher prevalence of thyroid autoimmunity in certain populations, including children, adolescents, and obese individuals. Moreover, vitamin D supplementation has shown promise in reducing antithyroid antibody levels, improving thyroid function, and improving other markers of autoimmunity, such as cytokines, e.g., IP10, TNF-α, and IL-10, and the ratio of T-cell subsets, such as Th17 and Tr1. Studies suggest that by impacting various immunological mechanisms, vitamin D may help control autoimmunity and improve thyroid function and, potentially, clinical outcomes of HT patients. The article discusses the potential impact of vitamin D on various immune pathways in HT. Overall, current evidence supports the potential role of vitamin D in the prevention and management of HT, although further studies are needed to fully understand its mechanisms of action and potential therapeutic benefits.

Vitamin D and the Thyroid: A Critical Review of the Current Evidence

Vitamin D is necessary for the normal functioning of many organs, including the thyroid gland. It is, therefore, not surprising that vitamin D deficiency is considered a risk factor for the development of many thyroid disorders, including autoimmune thyroid diseases and thyroid cancer. However, the interaction between vitamin D and thyroid function is still not fully understood. This review discusses studies involving human subjects that (1) compared vitamin D status (primarily determined by serum calcidiol (25-hydroxyvitamin D [25(OH)D]) levels) with thyroid function assessed by thyroid stimulating hormone (TSH), thyroid hormones, and anti-thyroid antibody levels; and (2) evaluated the effect of vitamin D supplementation on thyroid function. Due to the many inconsistencies in the results between the studies, it is still difficult to draw a definite conclusion on how vitamin D status affects thyroid function. Studies in healthy participants observed either a negative correlation or no association between TSH and 25(OH)D levels, while the results for thyroid hormones showed high variability. Many studies have observed a negative association between anti-thyroid antibodies and 25(OH)D levels, but equally many studies have failed to observe such an association. Regarding the studies that examined the effect of vitamin D supplementation on thyroid function, almost all observed a decrease in anti-thyroid antibody levels after vitamin D supplementation. Factors that could contribute to the high variability between the studies are the use of different assays for the measurement of serum 25(OH)D levels and the confounding effects of sex, age, body-mass index, dietary habits, smoking, and the time of year when the samples were collected. In conclusion, additional studies with larger numbers of participants are needed to fully understand the effect of vitamin D on thyroid function.

Relationship Between Vitamin D and Thyroid: An Enigma

Hypothyroidism is a frequently encountered endocrine disorder in clinical practice. Besides its traditional role in bone health, vitamin D has been shown to have favorable effects in a variety of different systems due to its pleiotropic qualities and ubiquitous receptor expression. Over the years, researchers have been fascinated by the intricate molecular interplay between vitamin D and thyroid. In this regard, attempts have emerged to demonstrate the role of vitamin D in thyroid disorders. This article has reviewed the existing literature on the role of vitamin D in hypothyroidism. We explored studies discussing the physiological interactions between vitamin D and thyroid, as well as the clinical consequences, supplemental and prognostic relevancy of vitamin D in auto-immune thyroid disease (AITD) and hypothyroidism.

The impact of exogenous vitamin D on thyroid autoimmunity in euthyroid men with autoimmune thyroiditis and early-onset androgenic alopecia

Background

Early-onset androgenic alopecia is regarded as the phenotypic equivalent of polycystic ovary syndrome in men. Women with polycystic ovary syndrome are at high risk of autoimmune thyroiditis. The aim of the current study was to investigate whether early-onset androgenic alopecia determines the impact of exogenous vitamin D on thyroid autoimmunity and thyroid function in men with autoimmune thyroiditis.

Methods

The study included 67 young men with autoimmune thyroiditis, 25 of whom had early-onset androgenic alopecia (group A). All 25 men with alopecia and 23 out of the 42 men with no evidence of hair loss, matched for age, antibody titers and thyrotropin levels (group B), were then treated with vitamin D (100 μg daily). Serum titers of thyroid peroxidase and thyroglobulin antibodies, serum levels of thyrotropin, free thyroid hormones, total and calculated free testosterone, dehydroepiandrosterone-sulfate, estradiol, prolactin and 25-hydroxyvitamin D, as well as the calculated parameters of thyroid homeostasis were assessed before vitamin D treatment and 6 months later.

Results

At baseline, thyroid antibody titers were higher in subjects with than without alopecia and correlated with calculated free testosterone levels. Vitamin D reduced antibody titers in both groups but this effect was stronger in group B than group A. Only in group B, vitamin D increased SPINA-GT. The impact of vitamin D on antibody titers correlated with 25-hydroxyvitamin D levels, calculated free testosterone, treatment-induced increase in 25-hydroxyvitamin D levels and the improvement in insulin sensitivity.

Conclusion

This study suggests that euthyroid men with early-onset androgenic alopecia may benefit to a lesser degree from vitamin D treatment than other subjects with autoimmune thyroiditis.

Associations Between Tenascin-C and Testosterone Deficiency in Men with Major Depressive Disorder: A Cross-Sectional Retrospective Study

Background

Elevated levels of tenascin-C are linked to increased risk and severity of major depressive disorder (MDD), while testosterone shows a protective effect. The present study explored associations between serum levels of tenascin-C and testosterone in Chinese men with MDD.

Methods

Testosterone and tenascin-C levels were measured in sera of 412 men with MDD and 237 age- and sex-matched controls. Serum levels of thyroid hormone, lipids, and high-sensitivity C-reactive protein (hs-CRP) were also quantified. Potential associations were examined using covariance, subgroup analysis, and multivariate linear regression analyses.

Results

Significantly higher concentrations of tenascin-C were detected in sera of subjects with MDD than in controls. Among subjects with MDD, testosterone concentrations inversely correlated with tenascin-C levels. This relationship was observed when patients were stratified by age at onset; duration or severity of depression; or concentration of thyroid hormones, low- or high-density lipoprotein, or hs-CRP. The negative association remained even when the statistical model was adjusted for age, smoking status, alcohol use, and body mass index. Linear regression with bootstrap resampling confirmed that high tenascin-C levels inversely correlated with testosterone levels.

Conclusion

In men with MDD, high tenascin-C concentrations correlate with testosterone deficiency. The combination of elevated tenascin-C and testosterone deficiency may be associated with MDD progression.

Dehydroepiandrosterone potentiates the effect of vitamin D on thyroid autoimmunity in euthyroid women with autoimmune thyroiditis: A pilot study

The impact of androgens on the thyroid in women is poorly understood. The aim of the present study was to investigate whether vitamin D/dehydroepiandrosterone (DHEA) combination therapy is superior to vitamin D alone in affecting thyroid autoimmunity and hypothalamic-pituitary-thyroid axis activity in young women with autoimmune thyroid disease. The study included 35 euthyroid women with untreated Hashimoto's thyroiditis and reduced sexual drive, allocated to one of two treatment groups. The first group (n = 19) received both vitamin D and DHEA, while the second (n = 16) was treated with only vitamin D. Serum thyroid antibody titres and concentrations of thyrotropin, free thyroid hormones, dehydroepiandrosterone-sulphate (DHEA-S), 25-hydroxyvitamin D, testosterone and estradiol were measured at baseline and 6 months later. Vitamin D administered alone or in combination with DHEA decreased serum titres of thyroid peroxidase and thyroglobulin antibodies, which correlated with baseline antibody titres, baseline 25-hydroxyvitamin D levels and treatment-induced increase in 25-hydroxyvitamin D levels. Apart from a stronger effect on antibody titres, vitamin D/DHEA combination therapy slightly decreased thyrotropin levels, as well as increased DHEA-S and testosterone levels. In this group of women, treatment-induced changes in antibody titres and thyrotropin levels correlated with the impact on DHEA-S and testosterone. The obtained results suggest that vitamin D/DHEA combination therapy may be a better treatment option for euthyroid women with Hashimoto's thyroiditis than vitamin D alone.

Vitamin D and Autoimmune Thyroid Disease-Cause, Consequence, or a Vicious Cycle?

Vitamin D is a steroid hormone traditionally connected to phosphocalcium metabolism. The discovery of pleiotropic expression of its receptor and of the enzymes involved in its metabolism has led to the exploration of the other roles of this vitamin. The influence of vitamin D on autoimmune disease-namely, on autoimmune thyroid disease-has been widely studied. Most of the existing data support a relationship between vitamin D deficiency and a greater tendency for development and/or higher titers of antibodies linked to Hashimoto's thyroiditis, Graves' disease, and/or postpartum thyroiditis. However, there have also been some reports contradicting such relationships, thus making it difficult to establish a unanimous conclusion. Even if the existence of an association between vitamin D and autoimmune thyroid disease is assumed, it is still unclear whether it reflects a pathological mechanism, a causal relationship, or a consequence of the autoimmune process. The relationship between vitamin D's polymorphisms and this group of diseases has also been the subject of study, often with divergent results. This text presents a review of the recent literature on the relationship between vitamin D and autoimmune thyroid disease, providing an analysis of the likely involved mechanisms. Our thesis is that, due to its immunoregulatory role, vitamin D plays a minor role in conjunction with myriad other factors. In some cases, a vicious cycle is generated, thus contributing to the deficiency and aggravating the autoimmune process.