Endocrine Abstracts

Introduction: Autoimmune thyrotoxicosis (AT) affects 2-5% of the Western population. Despite current NICE guidelines recommending radioiodine as first-line treatment for AT, practical considerations such as licensing often prevent this. Typically, anti-thyroid medication (carbimazole or propylthiouracil) is initially offered. Patients are usually counselled that the remission rate following a 12-18 month course of anti-thyroid medication is approximately 50%.

Aims: 1. To determine whether maintenance of remission using anti-thyroid medication coincides with the current consensus. 2. To determine if a difference exists in maintenance of remission between genders. 3. To determine whether a difference exists in the maintenance of remissionbetween patients with TSH-R Ab positivity vs TPO Ab positivity (at the start of treatment).

Methods: Our population comprised secondary care patients diagnosed with AT between 2014-2017, receiving a minimum of 18 months of anti-thyroid medication and at least 12 months of post-treatment follow-up. Failure to achieve remission was defined as patients who had 18 months of anti-thyroid medication without achieving euthyroidism, or those who achieved euthyroidism but became hyperthyroid thereafter.

Results: Comparing 68 females and 17 males, we found 71.67%±1.04% of people failed to achieve remission (females 70.58%, males 76.47%). Binomial distribution analysis showed statistical significance vs a null hypothesis of 50% remission (P< 10.0001). No significant differences in remission rates were found between antibody status (P > 0.05 for both TPO and TSH-R Ab positivity) or between gender (P > 0.05). 61.29% of patients who achieved euthyroidism and stopped anti-thyroid medication at 18 months subsequently relapsed.

Discussion: Failure to achieve remission with anti-thyroid medication was >50%, implying that we ought to counsel our patients as such. Contrary to the established literature, our small study did not demonstrate that gender or antibody status at diagnosis predicts the outcome following a course of anti-thyroid medication. Our data validates NICE recommendations that first-line treatment for AT should be radioiodine therapy.