Low Vitamin D Levels Linked With Thyroid Disorders, finds study
Vitamin D deficiency is among the most common health problems in the world in all age groups. In a study, researchers have found that lower vitamin D levels are linked with hypothyroidism, autoimmune thyroid disease (AITD) and Hashimoto's thyroiditis (HT). The study findings were published in the journal BMC Endocrine Disorders on August 21, 2021.
Over the last decades, numerous studies have indicated that low serum vitamin D levels are associated with a series of diseases such as high blood pressure, heart disease, diabetes, cancer, mood disorders, multiple sclerosis, and autoimmune diseases. The contribution of vitamin D to thyroid disorders has received paramount attention; however, results are conflicting. Therefore, Dr Gholamreza Askari and his team conducted a systematic review and meta-analysis to survey all observational studies regarding the association between serum vitamin D levels and thyroid disorders, including hypothyroidism, AITD, HT, and Graves' disease (GD) among the adult population.
The researchers searched PubMed, ISI Web of Science, Scopus, and Google Scholar databases up to March 2021 and included 35 studies (42 arms) to evaluate the relationship between serum levels of vitamin D and thyroid disorders. They reported the pooled effect as weighted mean difference (WMD) and 95% confidence interval (CI). They also performed a sensitivity analysis on each study as well as subgroup analyses based on age, gender, geographical region, study design, and population health status.
Key findings of the study:
♦ Upon analysis, the researchers found that serum vitamin D was markedly lower in
- Autoimmune thyroid diseases (AITD) (WMD − 3.1 ng/dl; 95% CI, − 5.57 to − 0.66; P = 0.013),
- Hashimoto's thyroiditis (HT) (WMD − 6.05 ng/dl; 95% CI, − 8.35 to − 3.75) and
- Hypothyroidism patients (WMD − 13.43 ng/dl; 95% CI, − 26.04 to − 0.81).
♦ However, they found no association with Graves' disease (GD) (WMD − 4.14 ng/dl; 95% CI, − 8.46 to 0.17).
The authors concluded, "In the present systematic review and meta-analysis, vitamin D levels were significantly lower in hypothyroidism, AITD, and HT patients compared to healthy people. However, there was no significant association between serum vitamin D and GD, except among subjects ≥40 years old."
They further added, "Well-designed prospective cohort studies and clinical trials are needed for a better understanding of the relationship between vitamin D and thyroid disorders."
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