“Most thyroid diseases and rheumatoid arthritis are chronic diseases, and unfortunately, early signs of thyroid dysfunction are not specific and are often overshadowed by clinical manifestations of other diseases."
Patients with rheumatoid arthritis (RA) are at an increased risk of developing thyroid dysfunction, particularly hypothyroidism, according to a study published in Frontiers in Endocrinology.1 Investigators urge biochemical examination of thyroid function in patients with RA and stated that larger, prospective studies are needed to explore causal relationships between thyroid dysfunction and RA. The impact of thyroid dysfunction on disease activity, medication safety, and drug efficacy should also be examined.
“Most thyroid diseases and rheumatoid arthritis are chronic diseases, and unfortunately, early signs of thyroid dysfunction are not specific and are often overshadowed by clinical manifestations of other diseases in the absence of biochemical tests of thyroid function,” investigators explained. “Thyroid dysfunction can be detrimental to health and, if left undiagnosed or treated, can have serious adverse consequences and, in exceptional cases, can be fatal.”
A systemic review and meta-analysis used online literature databases, including PubMed, the Cochrane Library, Embase, and Scopus from inception to March 25, 2022, to explore the link between RA and thyroid dysfunction. Eligible studies provided data on 1 or more cases of thyroid dysfunction in patients with RA and controls. Investigators evaluated pooled odds ratios (ORs) and corresponding 95% confidence intervals (CIs) for thyroid dysfunction in both patients with RA and non-RA patients.
In total, 29 studies, including 35,708 patients with RA, met the inclusion criteria. A meta-analysis reported that patients with RA had an increased risk of developing thyroid dysfunction when compared with patients without RA, particularly regarding hypothyroidism (OR 2.25, 95% CI 1.78–2.84) and subclinical hypothyroidism (OR 2.18, 95% CI 1.32–3.61). Risk of developing hyperthyroidism in RA was also higher when compared with control groups (OR 1.65, 95% CI 1.24–2.19) and patients with RA had more than twice the risk of developing subclinical hyperthyroidism when compared with controls (OR 2.13, 95%CI 1.25–3.63). Further subgroup analysis indicated that study type and sample source of the control group were the source of heterogeneity.
The study was limited by the uneven quality of the 29 included studies, with 13.79% of abstracts categorized as low quality. Another limitation was that all studies were observational in nature, which, among other issues, made it difficult to establish a causal relationship between RA diagnosis and thyroid dysfunction. The clinical criteria for evaluating the relationship between RA and thyroid dysfunction were inconsistent and should be addressed in future studies. Lastly, factors including sex, age, and disease course were not analyzed due to insufficient data.
“Our findings suggest that rheumatologists should screen RA patients for thyroid function and refer to endocrinologists to determine effective strategies for preventing and treating thyroid dysfunction,” investigators concluded. “Furthermore, since RA may share a common pathogenesis with most autoimmune thyroid diseases (AITDs) that cause thyroid dysfunction, there may also be corresponding treatment options. More potential mechanisms and treatment options should be explored in future studies.”
Liu YJ, Miao HB, Lin S, Chen Z. Association between rheumatoid arthritis and thyroid dysfunction: A meta-analysis and systematic review. Front Endocrinol (Lausanne). 2022;13:1015516. Published 2022 Oct 13. doi:10.3389/fendo.2022.1015516