Levothyroxine Replacement Alleviates Thyroid Destruction in Hypothyroid Patients With Autoimmune Thyroiditis: Evidence From a Thyroid MRI Study

Background: Autoimmune thyroiditis (AIT) is the most frequent cause of hypothyroidism. Our previous studies have shown that magnetic resonance T1-mapping is a new technique for quantitatively evaluating the degree of thyroid destruction in AIT patients. This study aimed to evaluate the effect of levothyroxine on thyroid destruction in hypothyroid AIT patients using thyroid T1-mapping technique. Methods: This study recruited 29 hypothyroid AIT patients and 18 age- and sex-matched healthy individuals. Thyroid T1-mapping values were measured in all participants and repeated in the AIT patients at 3 months after they achieved a euthyroid state following levothyroxine treatment. Results: Thyroid T1-mapping values were higher in the AIT patients than in the healthy controls (1167.2 ± 163.2 vs. 779.6 ± 83.8 ms, P < 0.01), and levothyroxine treatment significantly decreased the thyroid T1-mapping values of AIT patients (1006.3 ± 114.6 vs. 1167.2 ± 163.2 ms, P < 0.01). Meanwhile, the reduced levels of anti-peroxidase antibody (TPOAb) and anti-thyroglobulin antibody (TgAb) were observed in the AIT patients after levothyroxine treatment [TPOAb: 257.6 (23.9-960.6) vs. 1,287.4 (12.6-2000.0) IU/mL, P < 0.01; TgAb: 53.54 (9.58-386.2) vs. 103.9 (34.2-1,596.8) IU/mL, P < 0.05]. High-sensitivity C-reactive protein (hsCRP) levels showed a descending tendency following levothyroxine treatment, although there was no statistical difference (P > 0.05). Conclusions: In the AIT patients, thyroid T1-mapping values were significantly increased, and levothyroxine treatment significantly decreased the thyroid T1-mapping values of the AIT patients. These results might suggest that levothyroxine treatment alleviates thyroid destruction in hypothyroid AIT patients.