ABSTRACT
Objective:To investigate the effect of levothyroxine withdrawal before radioiodine therapy on blood lipids and renal function in patients with differentiated thyroid carcinoma (DTC) after operation.Methods:From Mar. 2020 to Apr. 2022, 214 patients with differentiated thyroid cancer were enrolled in the General Surgery Department, Linyi Central Hospital, Shandong Province. All patients stopped taking levothyroxine sodium after total thyroidectomy. The thyroid function index, blood lipid index and renal function index were measured and compared before and after drug withdrawal (before operation) and after drug withdrawal (before radioiodine treatment). The patients were divided into groups according to the duration of drug withdrawal (drug withdrawal group for 3 weeks, drug withdrawal group for 4 weeks), and the differences of thyroid function index, blood lipid index, and renal function index among patients with different drug withdrawal time were compared. The measurement data in accordance with normal distribution were compared between groups, and independent sample t-test was performed. Results:The levels of free thyroxin T4 (FT 4) and free triiodothyronine (FT 3) in DTC patients decreased significantly ( t=57.60, 71.74,all P<0.001), and the levels of thyroid-stimulating hormone (TSH) increased significantly ( t=102.15, P<0.001). After drug withdrawal, the serum lipid index [triglyceride (TG), total cholesterol (TC), high-density lipoprotein (HDL), low density lipoprotein (LDL) ] and renal function index [blood urea nitrogen (BUN), serum creatinine (SCR) ] of DTC patients increased significantly ( t=20.17, 42.50, 12.13, 30.73, 16.09, 43.73, all P<0.001). The levels of FT 3 and FT 4 in the 4-week group were significantly lower than those in the 3-week group ( t=7.75 and 10.07, both P<0.001), and TSH was significantly higher than that in the 3-week group ( t=26.46, P<0.001). The levels of TG, LDL, HDL, TC, BUN and Scr in the 4-week group were significantly higher than those in the 3-week group ( t=10.13, 10.29, 8.53, 11.47, 10.54, 8.55, all P<0.001). Correlation analysis showed that the levels of FT 3 and FT 4 in DCT patients were negatively correlated with the levels of TG, LDL, HDL, TC, BUN and Scr ( r=-0.256, -0.189, -0.249, -0.314, -0.352, -0.231, -0.342, -0.259, -0.304, -0.216, -0.391, -0.271, P=0.011, 0.029, 0.007, 0.004, 0.015, 0.036, 0.002, 0.009, 0.019, 0.017, 0.016, 0.003), and the levels of TSH were correlated with TG, LDL, HDL, TC and BUN Scr level was positively correlated ( r=0.257, 0.308, 0.219, 0.311, 0.251, 0.271, P=0.006, 0.013, 0.032, 0.004, 0.006, 0.014) . Conclusion:Stopping levothyroxine sodium before radioactive iodine treatment after DTC can easily lead to dyslipidemia and decreased renal function in patients, and the longer the withdrawal time is, the more obvious the changes of blood lipids and renal function in patients, and the withdrawal time should be shortened in clinical treatment.