Endocrine Abstracts

Introduction: Failure of medical treatment in patients with primary diffuse toxic goitre (Graves’disease) was reported in around 50% of patients and can occur few months after cessation of therapy. Radioactive I131 therapy is a good therapeutic alternative that can be used safely in patients with relapsed Graves’ disease and achieve good response rate with hypothyroisdism representing the main side effect.

Aim: The aim of the current study is to asses one year response rate to 10 mCi of I131 in patients with relapsed Graves’ disease post failure of medical treatment patients and methods: 33 patients who had transient control of clinical manifestations with normal thyroid hormonal profile post at least 12 months of continuous proper dose of of neomercazole therapy were included. This was followed by variable period of disease control (range: 7–19 months). After a mean period of 13.4±5.5 months with no thyrotoxic clinical manifestations and more importantly normal thyroid hormonal profile during follow up, all patients had clinically and biochemically confirmed thyrotoxic state with a diagnosis of relapsed primary diffuse toxic goiter (relapsed Graves’ disease). All presented for I131 therapy post failure of medical treatment and confirmed relapse. They received 10 mCi of I131 on out patient basis. Patients were followed up for 1 year to assess response to I131 therapy.

Results: 14 patients (40.4%) developed clinical hypothyroidism that was confirmed biochemically 3 months post I131 therapy. 1 year post 10 mCi of I131 both clinical and biochemical data showed overt hypothyroid state in 21 patients (63.6%). One patient (3%) with subclinical hypothyroidism was diagnosed by thyroid function tests with no clinical symptoms. Normal thyroid function tests with no clinical manifestations of recurrence were reported in eight patients (24.4%). Considering both hypothyroid and euthyroid states as successful response to I131 therapy, so the overall successful response rate post 1 year of 10 mCi of I131 therapy is 91%. Failure of response to 10 mCi of I131 with a need for a second I131 dose was reported in only three patients (9%).

Conclusion: 10 mCi of I131 is a good therapeutic choice in patients with relapsed Graves’ disease with an overall response rate 1 year post I131 therapy of 91%. Hypothyroidism occurs as early as 3 months post therapy in around 40% of patients, increasing to 66.6% by the end of first year after therapy.