High vitamin D status in younger individuals is associated with low circulating thyrotropin

Thyroid. 2013 Jan;23(1):25-30. doi: 10.1089/thy.2012.0001. Epub 2012 Dec 16.

Abstract

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 55.0±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 30 ng/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.

Publication types

  • Research Support, Non-U.S. Gov't

MeSH terms

  • 25-Hydroxyvitamin D 2 / blood*
  • 25-Hydroxyvitamin D 2 / immunology
  • Adolescent
  • Adult
  • Age Factors
  • Aged
  • Aged, 80 and over
  • Autoantibodies / blood
  • Calcifediol / blood*
  • Calcifediol / immunology
  • Female
  • Humans
  • Immunologic Factors / blood
  • Iodide Peroxidase / immunology
  • Male
  • Middle Aged
  • Nutritional Status
  • Thailand
  • Thyroglobulin / immunology
  • Thyrotropin / blood*
  • Thyrotropin / immunology
  • Young Adult

Substances

  • Autoantibodies
  • Immunologic Factors
  • thyroid microsomal antibodies
  • 25-Hydroxyvitamin D 2
  • Thyrotropin
  • Thyroglobulin
  • Iodide Peroxidase
  • Calcifediol