The Features of Thymic Hyperplasia in Graves' Diseases: Relationships between Serum Thyroid Hormones and TRAb

Abstract

Abstract Background This study aimed to analyze the clinical features of Graves' Diseases (GD) with and without thymic hyperplasia (TH).Methods Between 2018 and 2020, we reviewed 257 patients with GD. Based on thyroid evaluations and radiological, clinical, and serological findings, the patients were divided into the TH + group (GD patients with disorders in their thymus glands) or group TH- (GD patients with normal thymus glands). Then we compared the differences in clinical and serological features between groups.Results Of the 257 GD patients, 151 (58.75%) were classified into the TH + group. There was no significant difference in gender distribution between the two groups. The patients with TH showed an evident low age preponderance. The family history of autoimmune thyroid diseases (AITD), smoking history, Graves' Ophthalmopathy (GO) incidence, and periodic paralysis was not different.In the TH + group, body mass index (BMI) and TSH were significantly lower than those in TH- group, while levels of free T3, free T4, and TRAb of the TH + group were higher than those in the TH- group. The groups did not differ in levels of TPOAb and TGAb. The significant risk factors for TH in GD patients were free T3 and age. In comparison, free T3 was an essential and independent factor for TH.Conclusion Over half of GD patients are complicated by TH. Patients with TH are younger and exhibits the characteristic of significant hyperthyroid and TRAb-positive status. Free T3 was an essential and independent factor for TH.