New research out of South Korea suggests there is an association between vitamin D deficiency and autoimmune thyroid disease.
Vitamin D deficiency has been linked to many autoimmune diseases, including type 1 diabetes, systemic lupus erythematosus, multiple sclerosis, and Crohn’s disease, with studies finding a higher prevalence of these diseases in those who are deficient in vitamin D. However, to date, the link between vitamin D and autoimmune thyroid disease (AITD) has been less clear.
Recently, researchers out of University of Ulsan College of Medicine in Seoul, South Korea, wanted to further study this relationship, to see if they could find a link between vitamin D and AITD.
AITD is an autoimmune disease where the body mistakenly perceives the thyroid and the hormones it produces as threats, and thus produces antibodies to fight thyroid cells. AITD causes changes in thyroid hormone levels, which makes it hard for the body to function properly. Some signs and symptoms include fatigue, weight gain, difficulty concentrating, drowsiness and muscle soreness.
There are many markers and tests that in combination can diagnose AITD. One marker is level of antibodies specific to fighting thyoid-related cells.
In the present study, researchers looked at vitamin D levels and how they correlated with the presence of the antibody TPO-Ab. Presence of TPO-Ab signals that the body has or has had an attack on the thyroid.
The researchers looked at 6,685 patients who visited the Asian Medical Center between 2008 and 2012 for routine checkup. All patients had blood drawn, so the doctors could measure both TPO-Ab and vitamin D.
The researchers divided patients into three categories, those who were severely deficient in vitamin D (had levels less than 10 ng/ml), deficient in vitamin D (levels between 10-30 ng/ml) and those who were sufficient in vitamin D (over 30 ng/ml).
What they found is that people who were deficient in vitamin D were much more likely to have TPO-Ab positive tests. The prevalence of TPO-Ab positive tests was 21.2% in the severely vitamin D deficient group, 15.5% in the deficient group, and just 12.6% in the sufficient group.
The researchers calculated that those who were severely deficient in vitamin D had nearly twice as high the risk of a positive TPO-Ab test compared to those who were sufficient (OR=1.95, P=0.001).
“These findings suggest a possible role of vitamin D in the development of AITD and a potential crosstalk mechanism between vitamin D and estrogen in the pathogenesis of thyroid autoimmune disease,” the researchers said. “A future longitudinal cohort study and prospective interventional trials based on the community population may further clarify the role of vitamin D in thyroid autoimmune disease.”