The prevalence of thyroid dysfunction and autoimmune thyroid disease in patients with rheumatoid arthritis

BACKGROUND: Rheumatoid arthritis (RA) is one of the most common chronic non-organ-specific autoimmune diseases; meanwhile, autoimmune thyroid disease (AITD) is the most common organ-specific autoimmune disease that can lead to hypo or hyperthyroidism.

Although the etiology of both diseases is complex with a combination of genetic and environmental factors, there are overlaps in genes contributing to the pathogenesis of both diseases.

Numerous studies found a correlation between thyroid abnormality and RA in different populations, yet some didn’t.

This study is aimed to evaluate the prevalence of thyroid dysfunction, AITD, and anti-thyroid peroxidase (anti-TPO) positively in Iranian patients with RA.

METHODS: A total of 250 RA patients and 248 patients with non-inflammatory rheumatologic disease were included in this case–control study.

All participants underwent complete clinical and laboratory assessments.

Participants were also assessed for thyroid function testing, including anti-TPO antibodies.

RESULTS: Thyroid dysfunction was twice as common in RA patients as in controls (OR = 2.16; P-value > 0.001).

Overt hypothyroidism was the most common thyroid dysfunction among RA patients (58 out of 84).

Anti-TPO positivity was also significantly more common in RA compared with controls (OR = 2.65; P-value > 0.001).

The proportion of controls and RA patients with AITD were 9 and 21.5%, respectively.

AITD was found 2.8 times more common in RA group than controls (OR = 2.77; P-value > 0.001).

CONCLUSION: It was demonstrated that RA was an independent factor associated with thyroid dysfunction and AITD.

SUPPLEMENTARY INFORMATION: The online version contains supplementary material available at 10.1186/s41927-022-00293-9.