Endocrine Abstracts

Background: Recent NICE guidance recommends radioactive iodine as the first line treatment for relapsed thyrotoxicosis as it reportedly produces better control than long-term anti-thyroid drugs (ATDs).However, almost all studies of long-term ATDs relapse occurs after discontinuation of a medication. We present a retrospective analysis of efficacy of ATDs.

Methods: Data of all patients with hyperthyroidism, attending Endocrinology clinic at Morriston Hospital were collected from electronic database (Leicester database). Thyroid function test results obtained from the pathology.

Results: Total of 695 patients with thyrotoxicosis were identified between 1997 to 2020. Of 695, 476(68%) patients were diagnosed with autoimmune hyperthyroidism (Graves disease) and 99(14%) with toxic multinodular (TMNG) /solitary goitre 99(14%) and other aetiology 120(17.2%). The median length of follow up was 2.75 years(1month to 22 years). Of 476 patients with autoimmune disease, 385 were treated with ATDs. Out of 385 patients, 85 continued on long term ATDs and 300 discontinued after 12-18 months of treatment. Out of 300 who discontinued ATDs, 108 relapsed and the median time of relapse was 11.5 months. Out of 108 who relapsed, 87 were re-started on ATDs and continued on long term treatment. In total 167(97%) patients with autoimmune hyperthyroidism on long-term ATDs remained in remission with normal TSH after a median period of follow up of 37 (range 2-263) months. Of 99 patients with toxic goitre, 75 were treated with ATDs. Out of 75 patients, 39 continued on long term ATDs and 36 discontinued after 12 to 18 months. Out of 36 patients in remission after 12-18 months treatment 14 relapsed. Out of 14 relapsed patients10 were restarted on long term ATDs. In total 49 patients with toxic goitre were treated with long term ATDs. These patients maintained remission after median period of follow up of 38 (range 1 to 204) months with no relapse. Of 120 patients in other aetiology, 116 out of 120 were started on ATD. Out of 116,34 patients went into remission after 12-18 months and discontinued treatment and 10 continued on longterm treatment. No data available for 71 patients. Out of 10 relapsed patients 4 were restarted on ATD. In total 14 patients in non-specific group were treated with long term ATDs.

Discussion: Our study demonstrates that long-term maintenance dose of ATDs are effective in maintaining euthyroidism in both Graves’ disease and TMNG.