Low blood levels of vitamin D3 appear to be significantly linked to autoimmune thyroid disease, especially in premenopausal women, according to recent findings.
In a cross-sectional study, researchers evaluated 6,685 patients seen for routine checkups at the Asan Medical Center in Seoul, Korea, between 2008 and 2012. The checkups included blood tests of serum 25-hydroxyvitamin D3 and antithyroid peroxidase antibody (TPO-Ab), as well as ultrasonography of the thyroid. Of the study participants, 58% were men and 42% were women.
All patients were examined and interviewed by physicians in the health promotion center. Self-administered questionnaires were used to collect information about the patients’ menopausal status, history of previous disease and medication, and history of prior surgery.
The researchers defined autoimmune thyroid disease in two ways: serum TPO-Ab positivity and both TPO-Ab and ultrasound positivity.
The researchers found that the overall rate of TPO-Ab positivity was 10.1% (6.3% men; 15.3% women), and the rate of TPO-Ab/ultrasound positivity was 5.4% (2.3% men; 9.7% women). Among the female participants, the mean serum 25-(OH)D3 levels were significantly lower in the TPO-Ab–positive (22 ng/mL vs 23.5 ng/mL; P=.03) and TPO-Ab–positive/ultrasound-positive (21.6 ng/mL vs. 23.4 ng/mL; P=.027) groups compared with the control group. Also, in women, the rate of TPO-Ab positivity and TPO-Ab/ultrasound positivity was found to decrease according to the serum levels of 25-(OH)D3 (P=.001). This correlation was found to be significant in premenopausal women (P=.003 and P<.001, respectively, for both positive groups) but not in postmenopausal women. According to multivariate analysis, the adjusted OR for autoimmune thyroid disease in the 25-(OH)D3–deficient (TPO-Ab–positive: OR=1.95, P=.001; TPO-Ab–positive/ultrasound-positive: OR=2.36, P<.001) and 25-(OH)D3–insufﬁcient groups (TPO-Ab–positive: OR=1.31, P=.043; TPO-Ab–positive/ultrasound-positive: OR=1.5, P=.017) were significantly higher compared with the 25-(OH)D3–sufficient group.
The researchers said their findings may indicate an interaction between vitamin D and estrogen in the etiology of autoimmune thyroid disease.
“These findings suggest a possible role of vitamin D in the development of [autoimmune thyroid disease], and a potential crosstalk mechanism between vitamin D and estrogen in the pathogenesis of [autoimmune thyroid disease],” the researchers wrote. “A future longitudinal cohort study and prospective interventional trials based on the community population may further clarify the role of vitamin D in [autoimmune thyroid disease].”
Disclosure: The researchers report no relevant financial disclosures.