Impact of DIO2 genetic polymorphisms on levothyroxine bioavailability in Egyptian hypothyroid patients’ post-total thyroidectomy

Background: Hypothyroidism is a common endocrine disorder primarily treated with levothyroxine (L-T4). Individual variations in L-T4 requirements may be influenced by genetic factors, particularly polymorphisms in genes involved in thyroid hormone metabolism. The deiodinase type 2 (DIO2) enzyme plays a crucial role in converting T4 to the active form T3. The aim of the study is to evaluate the effect of DIO2 genetic polymorphism (rs225014) on levothyroxine bioavailability in Egyptian patients who have undergone total thyroidectomy. This case-control study included 120 participants enrolled into 3 equal groups: controls, high-dose levothyroxine (≥1.7 μg/kg/day), low-dose levothyroxine (