A Prospective Study to Evaluate the Possible Role of Cholecalciferol Supplementation on Autoimmunity in Hashimoto's Thyroiditis

Abstract

A Prospective Study to Evaluate the Possible Role of Cholecalciferol Supplementation on Autoimmunity in Hashimoto's Thyroiditis Biva Bhakat1 , Jyotirmoy Pal2 , Sukdeb Das3 , Sumit Kr Charaborty4 1,3Nil Ratan Sircar Medical College, Kolkata, 2 RG Kar Medical College and Hospital, 4 North Bengal Medical College, Siliguri Introduction: Hashimoto thyroiditis (HT) is an autoimmune disease that destroys thyroid cells by antibody and call-mediated immune processes. Hashimoto thyroiditis is the commonest cause of goitre in iodine-sufficient regions.[1] The aetiology of Hashimoto disease is very poorly understood. Most patients develop antibodies to a variety of thyroid antigens, the most common of which is anti-thyroid peroxidase (anti-TPO). Many also form antithyroglobulin (anti-Tg) and TSH receptor blocking antibodies (TBII). These antibodies attack the thyroid tissue, eventually leading to inadequate production of thyroid hormone. There is a small subset of the population, around 10-15% with the clinically evident disease, that are serum antibody-negative.[2][3] The mechanisms underlying the assumption that vitamin D is linked with autoimmunity are not clear but probably are associated with its anti-inflammatory and immunomodulatory functions. The dendritic cells are antigen-presenting cells originating from bone marrow and also a primary target for the immunomodulatory activity of vitamin D. 1,25[OH]2D has direct immunomodulatory effects at the level of the T cell vitamin D receptor. Together, these immunomodulatory effects can lead to the protection of target tissues, such as thyroid cells in autoimmune diseases. Considering that in HT, a disorder of T cell-mediated immunity, immunologic attack is triggered when thyrocytes express MHC class II surface HLA-DR antigens, a process induced by the production of Th1 type inflammatory cytokines (especially IFN-γ). Moreover, at another stage, after being activated by T cells, B cells' ongoing proliferation might be inhibited and apoptosis might be induced by 1,25[OH]2D. Thus, 1,25[OH]2D might decrease antibodies that react with thyroid antigens. The exact levels of vitamin D that are sufficient to improve the immune regulatory function and lead to an effective immune response, should be investigated. Several clinical studies have reported a low vitamin D status in AITD or HT, indicating an association between vitamin D deficiency and thyroid autoimmunity. If supplementation of the Vitamin D decreased thyroid antibody titres in Vitamin D deficient subjects, in the future Vitamin D may become a part of AITDs' treatment, especially in those with Vitamin D deficiency. [4] So, our study tries to assess any potential therapeutic role of vitamin D in the management of patients with Hashimoto's thyroiditis.

Aims and objectives: Most studies have shown an association between low vitamin D status and pathogenesis of AITD, especially HT. However, there are only few preliminary interventional studies for HT. whether vitamin D supplementation is beneficial for AITD or HT, should be evaluated. Treatment of HT mainly based on thyroid hormone supplementation, so if a beneficial role of vitamin D supplementation is identified/ confirmed, it will be helpful in the treatment of patients with HT and may be a part of treatment of HT patients.

Aims and objectives: Evaluating the role of vitamin D on an excessive thyroid immune response.

Materials and methods: Study area: N.R.S. Medical college and hospital, Kolkata (Department of General Medicine).

Study period: 1 year (January,2019 to December,2019 Sample size: 100 patients both male and female. Sample Design: Patients attending outpatient dept in N.R.S medical college.

Study design: Prospective, hospital based, single centre study.

Inclusion criteria: Newly diagnosed patients (age >18 years and of both sexes) with HT and vitamin D deficiency.

Exclusion criteria: Patients suffering from: Other autoimmune diseases. Chronic illnesses like diabetes mellitus, chronic kidney disease, chronic liver disease, malignancy. Pregnancy Study tools: Estimation from serum: TSH. Free thyroxine (FT4) 25 hydroxy vitamin D Anti-thyroid peroxidase (anti-TPO) antibody' Study techniques: This is a prospective study conducted in N.R.S Medical college, Kolkata, India. Total 100 adult patients of both sexes diagnosed with HT and vitamin D deficiency (vit D<30 ng/ml)12, having none of the exclusion criteria and getting treatment on out-patient department basis, who gave informed consent were included in our study. Blood samples drawn for anti TPO antibody and 25hydroxy vitamin D from all the participants. The correlations between serum Vit D and anti TPO antibody were measured and presented by correlation coef ficient (r2). Study participants are randomly assigned into two groups by random permuted block. Cholecalciferol supplement given in the dose of 60,000 IU weekly for 8 weeks in one group (n = 50). Another group (n = 50) were given placebo (empty soft gelatine capsule). At the onset of the study, patients were requested to keep their habitual diet and routine level of physical activity throughout the study period and not to take any medication that might affect their reproductive physiology. Compliance to the consumption of supplement and placebo was examined by empty blister packets. However, 2 patients from cholecalciferol group and 1 patient from control group lost to follow up. After 8 weeks blood anti TPO antibody level measured in both the groups (n = 48 & 49 in 2 group). The change in the mean value of anti TPO antibody measured and statistical significance of the change checked. Results considered significant or non-significant when P> or < 0.05, respectively. TSH, T4 measurement Performed with chemiluminescence using ADVIA Centaur XP Immunoassay System. Work plan: Study was done over 12 months. Data collected and compilation done and then statistical analysis done by standard statistical method.

Statistical analysis: For statistical analysis data were entered into a Microsoft excel spreadsheet and then analyzed by SPSS (version 27.0; SPSS Inc., Chicago, IL, USA) and GraphPad Prism version 5. p-value ≤ 0.05 was considered for statistically significant. The Negative Correlation was found between Serum 25 hydroxy vitamin D (ng/ml) vs Serum TSH (mU/L) which was statistically significant. Distribution of mean serum anti-TPO antibody level (IU/ml) [mean±SD] in both groups before and after intervention <img src="https://www.japi.org/article/images/2023-01-08_1673190869.png" style="width: 274px;"> Reduction of serum anti-TPO antibody level in cholecalciferol group is 30.5% and reduction of serum anti-TPO antibody level in placebo group is 16.5%.

Discussion: This study is carried out with the total no. of 100 outdoor based patients of diagnosed Hashimoto's Thyroiditis (elevated Anti-thyroid peroxidase antibody) and vitamin D deficiency (vit D &lt; 30 ng/mL)12 in Nil Ratan Sircar medical college and hospital within the mentioned study period. The study focussed on evaluating the role of vitamin D on an excessive thyroid immune response i.e. the effect of vitamin D supplementation on thyroid autoimmunity and that low vitamin D levels and the risk of HT are closely associated and the potential application of vitamin D in the treatment of AITD. The result demonstrates a negative Correlation between Serum 25 hydroxy vitamin D (ng/mL) vs anti TPO antibody (IU/ml) which was statistically significant. Pearson Correlation Coefficient (r)= -0.775, p value = 0.0001. Goswami et al. conducted a community-based survey on 642 adults to investigate the relationship between serum vitamin D concentrations and thyroid autoimmunity. Their results highlighted a significant inverse association between 25(OH)D3 and TPO Ab levels [40]. This inverse correlation was substantiated in the following studies.[5-8] As regards thyroid function in the context of HT, Mackawy and co-workers demonstrated a strong negative association between serum vitamin D concentrations and TSH levels, leading to speculate that vitamin D deficiency in HT patients could be associated with a progression towards hypothyroidism (TSH &gt; 5.0 m UI/L) [45]. Our study also demonstrates negative Correlation between Serum 25 hydroxy vitamin D (ng/mL) vs Serum TSH (mU/L) and the result was statistically significant. Pearson Correlation Coefficient (r) = -0.301, p value = 0.003. So, the results indicate that vitamin D deficiency is a risk factor of Hashimoto's thyroiditis. Mean (mean± s.d.) Serum anti TPO antibody (IU/ml) before intervention was 545.06± 230.82 and after cholecalciferol supplementation the mean value decreased to 378.6± 160.49. So, there is a 30.5% reduction in the mean value of anti TPO antibody level. Difference of mean Serum anti TPO antibody (IU/mL) was statistically significant (p &lt; 0.0001). In the placebo group the mean Serum anti TPO antibody (IU/ml) (mean ± s.d.) of patients was 686.97± 290.19 and after 8 weeks of placebo the mean value was 573.1 ± 254.09. So, in the placebo group the reduction is only 16.5%. Difference of mean Serum anti TPO antibody (IU/ml) was statistically significant (p &lt; 0.0001). Therefore, in line with the hypothesis the data contributes clearer understanding that vitamin D supplementation results in a reduction of thyroid autoimmunity. This result also supports the previous research. Simsek et al. prospectively evaluated 82 patients with HT randomized in two groups: the first group treated with cholecalciferol for one month and the second group without vitamin D replacement. Their results showed that TPO Ab and Tg Ab levels were significantly decreased by the vitamin D replacement therapy in the first group [46]. These findings were also confirmed by other prospective studies and randomized controlled trials.[9-11] So, the result of our study clearly indicates that vitamin D supplementation could exert a positive effect on thyroid function as well as thyroid autoimmunity Limitations: Vitamin D status is not measured at the end of 8 weeks because of economic constraints. So, it is difficult to determine the optimal level of vitamin D needed for improving the evolution of this immunological disorder. Cholecalciferol is used in HT patients in our study, although active form calcitriol might be more beneficial as vitamin D binding protein level may affect the conversion of inactive vitamin D form and thus alters its function on immune cells. HT patients with normal vitamin D level have been excluded from the study, so from our study we cannot comment on beneficial effect of vit D supplementation in HT patient with normal vit D level. As we used empiric dose of levothyroxine in both the groups instead of a fixed dose, we could not analyze the potential role of vitamin D supplementation in reduction of serum TSH in HT There is still a gap in the knowledge regarding the potential of vitamin D supplementation in the treatment of HT patients whether vitamin D supplementation will help in decreasing the replacement dose of levothyroxine or whether it will stop the need of levothyroxine replacement if used in early stages of HT.

Conclusions: The 8 weeks randomized; double-blind, placebo-controlled clinical trial demonstrates a negative correlation between Serum 25 hydroxy vitamin D vs anti TPO antibody level. Treatment with 60,000 IU cholecalciferol weekly for 8 weeks, is associated with significant decrease in antithyroid antibody titers. It also improved serum TSH level compared with the placebo, i.e. supplementary treatment with cholecalciferol seems to have beneficial effects on AITD. However, large multicentre studies are needed to investigate the impact of vitamin D supplementary treatment on meaningful long-term clinical end points in AITD. References Dana L. Mincer; Ishwarlal Jialal. StatPearls [Internet]. Hashimoto Thyroiditis. Treasure Island (FL): StatPearls Publishing; 2020 Jan. Leung AKC, Leung AAC. Evaluation and management of the child with hypothyroidism. World J Pediatr 2019;15(2):124-134. Yuan J, Sun C, Jiang S, et al. The pevalence of thyroid disorders in patients with vitiligo: a systematic review and meta-analysis. Front Endocrinol (Lausanne) 2018;. Front Endocrinol (Lausanne). 2018; 9:803. Yoo WS, Chung HK. Recent advances in autoimmune thyroid diseases. Endocrinol Metab (Seoul) 2016;31(3):379-385. Ke W, Sun T, Zhang Y, et al. 25-Hydroxyvitamin D serum level in Hashimoto's thyroiditis, but not Graves' disease is relatively deficient. Endocr J 2017;64(6):581-587. Shin D, Kim KJ, Kim D, et al. Low serum vitamin D is associated with anti-thyroid peroxidase antibody in autoimmune thyroiditis. Yonsei Med J 2014; 55:476-481. ElRawi HA, Ghanem NS, ElSayed, N.M.; et al. Study of vitamin D level and vitamin D receptor polymorphism in hypothyroid egyptian patients. J Thyroid Res 2019. Kim CY, Lee YJ, Choi J, et al. The association between low vitamin d status and autoimmune thyroid disease in korean premenopausal women: the 6th korea national health and nutrition examination survey, 2013-2014. Korean J Fam Med 2019;40:323-328. Chaudhary S, Dutta D, Kumar M, et al. Vitamin D supplementation reduces thyroid peroxidase antibody levels in patients with autoimmune thyroid disease: An open-labelled randomized controlled trial. Indian J Endocrinol Metab 2016;20:391-398. Krysiak R, Szkróbka W, Okopie´n, B. The effect of vitamin D on thyroid autoimmunity in levothyroxine-treated women with Hashimoto's thyroiditis and normal vitamin D Status. Exp. Clin. Endocrinol. Diabetes 2017;125:229-233. Krysiak R, Kowalcze K, Okopie´n B. Selenomethionine potentiates the impact of vitamin D on thyroid autoimmunity in euthyroid women with Hashimoto's thyroiditis and low vitamin D status. 2018;71:367-373. Mazokopakis EE1, Papadomanolaki MG, Tsekouras KC, et al. Is vitamin D related to pathogenesis and treatment of Hashimoto's thyroiditis? Hell J Nucl Med. 2015;18(3):222-7.