Background:
Vitamin d is an immunomodulator and may affect autoimmune thyroid diseases. vitamin d has also been shown to influence thyrocytes directly by attenuating thyrotropin (tsh)-stimulated iodide uptake and cell growth. however, it is unclear how vitamin d status is related to tsh at the population level. the goal of the present study was to investigate the relationship between vitamin d status and tsh levels according to thyroid autoantibodies in a population-based health survey in thailand.
Methods:
A total of 2582 adults, aged 15-98 years, were randomly selected according to the geographical region from the thailand 4th national health examination survey sample. by study design, the sexes were equally represented. serum levels of 25-hydroxyvitamin d [25(oh)d], tsh, the thyroid peroxidase antibody (tpoab), and the thyroglobulin antibody (tgab) were measured in all subjects.
Results:
The mean age was 55.0Β±0.4 (se) years. in subjects positive for serum tgab, serum tsh levels were higher, whereas total serum 25(oh)d levels were lower. in addition, the prevalence of vitamin d insufficiency in tgab-positive subjects was significantly higher than that observed in tpoab- and tgab-negative subjects, whether based on cutoff values of 20 or 30βng/ml: 8.3% vs. 5.6%, p<0.05; or 47.6% vs. 42.0%, p<0.05, respectively. however, vitamin d status was not associated with positive tpoab and/or tgab after controlling for sex and age. to explore the probable interaction between vitamin d status and age on serum tsh, analyses were performed according to age tertiles; it was found that higher 25(oh)d levels were independently associated with lower tsh, but only in subjects in the lowest age tertile.
Conclusions:
This population-based study showed that high vitamin d status in younger individuals is associated with low circulating tsh.