Background There is scarce information about the usefulness of ultrasound and biopsy of the thyroid gland in rheumatoid arthritis (RA) patients with thyroid nodules classified as TIRADS 4 (Thyroid Imaging Reporting and Data System). In this study, we also described the prevalence of thyroid dysfunction and autoimmune thyroid disease in a cohort of RA patients without comorbidities. The purpose of this study was to support the clinical utility of thyroid gland screening in RA.
Methods We included 78 RA patients and 81 healthy controls (HC) classified by thyroid function. All of them underwent thyroid ultrasound and anti-thyroid antibodies screening. Subjects with TIRADS ≥4 were subjected to fine needle aspiration biopsy (FNAB). Continuous variables were analyzed with Student t test. Categorical variables were evaluated with c2 test or Fisher exact test. Correlations between variables were tested with Pearson r coefficient.
Results We found hypothyroidism in 24.4% vs. 1.2% in RA compared to HC (P=0.003). Of these, 89.5% were classified as subclinical hypothyroidism and 10.5% as overt hypothyroidism. In hypothyroid vs. euthyroid RA patients, we found higher titers of anti-TPOAb (310.38±633.73 vs 31.26±27.13, P=0.01) and anti-TGAb (417.85±1052.51 vs 18.40±19.17, P=0.02). According to TIRADS classification, we found a statistical difference vs HC, being the most common TIRADS 1 in both groups, follow by 2,3,4a and 4b. FNAB was performed in 7 RA patients and 1 HC, all of them reported as autoimmune thyroiditis.
Conclusions The clinical and US assessment of the thyroid gland in RA patients showed that the TIRADS classification has to be interpreted with a different context applied for the general population, since, despite the risk of malignancy that implies TIRADS 4 category, all of our cases were classified with autoimmune thyroiditis. The most common functional thyroid status was subclinical hypothyroidism and not development of anti-thyroid antibodies. Further studies are needed to evaluate the utility of imaging, immunological and functional status of thyroid gland in RA
Disclosure of Interest None declared