Short-term hypothyroidism transiently impaired endothelial function in differentiated thyroid cancer patients

Abstract

Abstract Purpose: Endothelial dysfunction, which was associated with chronic hypothyroidism, was an early event in atherosclerosis. Whether short-term hypothyroidism following thyroxine withdrawal during radioiodine (RAI) therapy was associated with endothelial dysfunction in patients with differentiated thyroid cancer (DTC) was unclear. Aim of the study is to assess whether short-term hypothyroidism could impair endothelial function in the whole process of RAI therapy. Methods: We recruited fifty-one patients who underwent surgery and would accept RAI therapy for DTC. We analyzed thyroid function, endothelial function and serum lipids levels in patients at three time points: the day before thyroxine withdrawal (P1), the day before RAI administration (P2) and 4–6 weeks after RAI therapy (P3). A high-resolution ultrasound named flow-mediated dilation (FMD) was used to measure endothelial function of the patients. Results: We defined the FMD(%) value decreasing by more than 1% as impaired value. We analyzed the changes of FMD, thyroid hormone and lipids at three time points. FMD (%) was impaired at P2 compared to P1 and was recovered at P3 after restoring LT4 therapy (P1 vs P2 vs P3, 8.05±1.55 vs 7.26±1.50 vs 7.79 ± 1.38, P = 0.438). Among all parameters, the change of LDL cholesterol (ΔLDL) was the only factor correlated negatively with the change of FMD (ΔFMD) throughout the RAI therapy process (P1 − 2, r=-0.326, P = 0.020; P2 − 3, r=-0.306, P = 0.029). Conclusion: Endothelial function was transiently impaired in DTC patients at short-term hypothyroidism state during the RAI therapy, and immediately returned to the same state before RAI therapy after restoring LT4 therapy.