Efficacy of Anti-Thyroid Medications in Patients with Graves' Disease.

Introduction: Graves' disease (GD) is an autoimmune disorder characterized by hyperthyroidism due to increased thyroid-stimulating hormone receptor antibodies (TRAb).The treatment of GD often consists of radioactive iodine therapy, anti-thyroid drugs (ATD), or thyroidectomy. Since few studies have collected data on remission rates after treatment with ATD in Saudi Arabia, our study aimed to assess the efficacy and the clinical predictors of GD long-term remission with ATD use.

Method: We conducted a retrospective chart review study of 189 patients with GD treated with ATD between July 2015 and December 2022 at the endocrine clinics in King Abdulaziz Medical City in Riyadh. All GD patients, adults, and adolescents aged 14 years and older who were treated with ATD during the study period and had at least 18 months of follow-up were included in the study. Patients with insufficient follow-up and those who underwent radioactive iodine (RAI) therapy or thyroidectomy as first-line therapy for GD were excluded from the study.

Results: The study sample consisted of 189 patients, 72% of whom were female. The patients' median age was 38years (33, 49). A total of 103 patients (54.5%) achieved remission. The median follow-up period for the patients was 22.0 months (9, 36). Patients who achieved remission had lower mean free T4 levels (25.8pmol/l ± 8.93 versus 28.8pmol/l ± 10.82) (P value = 0.038) and lower median TRAb titer (5.1IU/l (2.9, 10.7)) versus (10.5IU/l (4.2, 22.5)) (P value = 0.001) than patients who did not achieve remission. Thirty-five out of 103 patients who achieved remission (34%) relapsed after ATD discontinuation. The patients who relapsed showed higher median thyroid uptake on 99mTc-pertechnetate scan than patients who did not relapse: 10.3% (5.19, 16.81) versus 6.0% (3.09, 12.38), with a P value of 0.03. They also received ATD for a longer period, 40.0 months (29.00, 58.00) versus 25.0 months (19.00, 32.50), with a P value of < 0.0001.

Conclusion: The remission of GD was achieved in approximately half of the patients treated with ATD; however, approximately one-third of them relapsed. Lower Free T4 and TRAb levels at diagnosis were associated with remission. Longer ATD use and higher thyroid uptake upon diagnosis were associated with relapse after ATD discontinuation. Future studies are necessary to ascertain the predictors of ATD success in patients with GD.