Endocrine Abstracts

Introduction: Grave’s disease is an autoimmune disorder and is considered the most common cause of hyperthyroidism. Its treatment options include medical therapy, radioactive iodine (RAI), and surgery. RAI is commonly employed for Grave’s disease regarding its efficiency and safety. Definitive hypothyroidism is the main goal of RAI and is typically achieved within the first 3 to 6 months of therapy. Transient hypothyroidism and recurrence of hyperthyroidism after RAI might occur in some patients. We herein describe 2 cases of transient hypothyroidism following RAI.

Observations: Case 1 is a 67-year-old patient with a history of hyperthyroidism revealed by cardiothyreosis (atrial fibrillation and heart failure) 20 years ago with levels of TSH<0.05 mUI/l. TSH receptor antibodies were positive confirming the diagnosis of Grave’s disease. He received RAI after 2 months of methimazole. Six months later he developed hypothyroidism requiring thyroxine supplementation. During the follow up, he presented low TSH levels although dose tapering, leading to the discontinuation of thyroxine after 8 years of supplementation. He remained euthyroid for 7 months then redeveloped hypothyroidism. Case 2 is a 52-year-old patient with type 1 diabetes mellitus. Grave’s disease was revealed by weight loss and a goiter. His initial TSH was suppressed He was treated by RAI he was hypothyroid post RAI and was put on thyroxin supplementation until he started in a 3 year time presenting with persistently low TSH levels despite lessening the doses, we decided not to follow through with treatment and the patient remained euthyroid despite a 4 year period of treatment withhold

Discussion: Transient hypothyroidism post RAI should be thought of after radioiodine therapy when patients present with a lessened daily needs of thyroxin. It leads to a variably lasting period of euthyroidism necessitating further monitoring of TSH levels.

Conclusion: Grave’s disease incidence is growing worldwide. RAI being the most common treatment for either complicated or recurrent cases or within patient’s preference. Transient hypothyroidism post radioiodine should be taken into account and further studies are needed to confirm it, describe what might be its causes and predicting factors.