Recreational Exercise and Inflammatory Patterns in Hashimoto’s Thyroiditis: Observations from a Cross-Sectional Study

In this cross-sectional observational study, we investigated whether recreational exercise (RE) influences systemic inflammation in Hashimoto's thyroiditis (HT) across different disease severity groups. We analyzed 403 participants from the Croatian Biobank of Patients with HT (CRO-HT), including 173 controls and 230 HT patients (euthyroid, levothyroxine [LT4]-treated, and hypothyroid). Serum levels of 92 inflammatory proteins were measured using the Olink^® Target 96 Inflammation panel, and exercise status was assessed via structured questionnaires. Linear regression revealed distinct protein associations depending on thyroid status. In controls, RE was associated with reduced MMP-10 and FGF-5, reflecting cardiovascular and muscle benefits. In euthyroid patients, RE was associated with decreased CXCL9 and TRAIL, implicating reduced type 1 inflammation and vascular risk. LT4-treated patients showed increases in IL-15RA and IL-24 with RE, suggesting improved muscle metabolism and anti-inflammatory effects. In hypothyroid patients, RE was associated with reduced CCL20 and increased HGF, while changes in TRANCE and TWEAK indicated mixed effects on bone and immune regulation. Notably, RE was associated with reduced CXCL9 and CCL20, two proteins previously linked to HT risk. Overall, RE is associated with distinct changes in inflammatory profiles across HT disease severity groups, with the most favourable responses observed in LT4-treated patients, suggesting synergy with hormone therapy.