Prevalence of vitamin D deficiency and its relationship with thyroid autoimmunity in Asian Indians: a community-based survey

Abstract

25-Hydroxy vitamin D (25(OH)D)deficiency is linked with predisposition to autoimmune type 1 diabetes and multiple sclerosis. Our objective was to assess the relationship between serum 25(OH)D levels and thyroid autoimmunity. Subjects included students, teachers and staff aged 16-60 years (total 642, 244 males, 398 females). Serum free thyroxine, thyroid-stimulating hormone (TSH), and thyroid peroxidase autoantibodies (TPOAb), intact parathyroid hormone and 25(OH)D were measured by electrochemiluminescence and RIA, respectively. Thyroid dysfunction was defined if (1) serum TSH $ 5 mU/ml and TPOAb . 34 IU/ml or (2) TSH $ 10 mU/ml but normal TPOAb. The mean serum 25(OH)D of the study subjects was 17·5 (SD 10·2) nmol/l with 87 % having values #25 nmol/l. TPOAb positivity was observed in 21 % of subjects. The relationship between 25(OH)D and TPOAb was assessed with and without controlling for age and showed significant inverse correlation (r 2 0·08, P¼ 0·04) when adjusted for age. The prevalence of TPOAb and thyroid dysfunction were comparable between subjects stratified according to serum 25(OH)D into two groups either at cut-off of #25 or . 25 nmol/l or first and second tertiles. Until recently, vitamin D deficiency was considered to be rare in India because of abundant sunshine (1,2) . However, a systematic study carried out in the year 2000 in Delhi showed the presence of low 25-hydroxy vitamin D (25(OH)D) in a majority of subjects including newborns, their mothers, healthy physicians, nurses, soldiers and those with vitiligo and albinism. Based on these study groups, subnormal serum 25(OH)D levels of Asian Indians could be linked to their skin pigmentation and poor sunshine exposure (1,3) . Subsequently, a series of studies have documented widespread hypovitaminosis D in north as well as south India (3 -5) . Besides bone mineral homeostasis, 25(OH)D deficiency has been associated with a wide range of non-skeletal effects including predisposition towards autoimmune disorders (6 -8) .The demonstration of vitamin D receptor in monocytes, dendritic cells and activated T cells indicates significant interaction between vitamin D and the immune system (6,7) . While the molecular mechanisms linking vitamin D with autoimmunity are under investigation, in vitro studies indicate an immunomodulatory effect of 1,25(OH)D on Th 1 , Th 2 , T regulator and dendritic cells leading to a shift towards activation of Th2 cells (6,7) . Clinical relevance of the mechanism is indicated by a number of studies showing increased prevalence of autoimmune disease such as multiple sclerosis in Canada and the northern part of the USA receiving less sunshine. Vitamin D supplementation resulted in decreased prevalence of autoimmune disorders such as type 1 diabetes and multiple sclerosis. A recent meta-analysis showed 29 % reduction in the risk of type 1 diabetes in children receiving vitamin D supplementation (9,10)

Low Levels of Serum Vitamin D3 Are Associated with Autoimmune Thyroid Disease in Pre-Menopausal Women

“…But the diagnosis can be made by clinical evaluation, antibody measurement, and US findings. Most studies that have evaluated the association of vitamin D and thyroid autoimmunity have used serum TPO-Ab levels as a marker of thyroid autoimmunity (13,17,18). However, we have here defined AITD in two ways, in terms of the serum TPO-Ab levels and thyroid US findings suggestive of thyroiditis.…”

“…Small case-control studies have suggested lower serum vitamin D levels or a higher prevalence of vitamin D insufficiency in patients with AITD compared with healthy controls (11)(12)(13)(14)(15)(16). However, another study reported no significant association between the serum vitamin D levels and thyroid autoimmunity (17). A recent study from the Departments of 1 Internal Medicine and 3 Radiology; 2 Health Promotion Center; Asan Medical Center, University of Ulsan College of Medicine, Seoul, Korea.…”

Correlation of Serum 25-Hydroxyvitamin D and Thyroid Hormones in Pregnant Women in Amman-Jordan

“…Many studies showed role of vitamin D on thyroid hormone due to its activity in thyroid gland [2,11] and even in patients with thyroid diseases and thyroid autoantibody [46,47]. However, few studies focus on the link between 25-(OH)D and thyroid hormones during pregnancy.…”

The effect of Vitamin D treatment on thyroid function and the levels of thyroid autoantibodies, TNF-α, IL-6, IL-1β in patients with autoimmune thyroiditis

“…In another study, no significant role for vitamin D was discovered in the pathogenesis of HT 19 . In the public-based research project conducted by Goswami et al, a significant inverse correlation between 25(OH)D and antiTPO levels were shown 20 . The effect of vitamin D treatment on thyroid functions and antibody levels was not evaluated in this study 20 .…”

“…In the public-based research project conducted by Goswami et al, a significant inverse correlation between 25(OH)D and antiTPO levels were shown 20 . The effect of vitamin D treatment on thyroid functions and antibody levels was not evaluated in this study 20 . We investigated the effect of vitamin D treatment on HT and have shown that it has a positive effect, however, we were not able to find any statistically significant correlation between 25(OH)D and TSH, antiTPO and antiTG levels.…”