Association Between Vitamin D Deficiency and Autoimmune Thyroid Disorder: A Systematic Review

Area of Science:

• Endocrinology and Immunology
• Nutritional Science

Background:

• Low serum 25-hydroxyvitamin D (25(OH)D) levels are suspected to influence autoimmune thyroid disorders (AITD).
• The specific relationship between vitamin D deficiency and Graves' disease (GD) and Hashimoto's thyroiditis (HT) remains unclear.

Purpose of the Study:

• To review and synthesize existing research on the association between vitamin D levels and AITD, specifically GD and HT.
• To evaluate the prevalence of vitamin D deficiency in patients with GD and HT compared to control groups.

Main Methods:

• Systematic search of PubMed/Medline, Google Scholar, and Cochrane Library for studies on vitamin D and HT/GD.
• Inclusion of observational, case-control studies comparing vitamin D levels in AITD patients and healthy controls.
• Final review included 11 studies (2011-2021) involving 1952 AITD cases.

Main Results:

• The majority of reviewed studies indicated a higher prevalence of vitamin D deficiency or low serum 25(OH)D levels in patients with HT and GD.
• Two studies did not find a significant association between vitamin D deficiency and HT or GD.

Conclusions:

• Vitamin D deficiency or insufficiency may increase the risk of developing autoimmune thyroid diseases such as HT and GD.
• Further randomized controlled trials with extended follow-up are necessary to establish a causal relationship and explore vitamin D supplementation efficacy.