Effects of High-Dose Radioactive Iodine Treatment On Renal Function In Patients With Differentiated Thyroid Carcinoma: A Retrospective Study

Abstract Aim: This study aimed to investigate the effects of high-dose radioactive iodine (131I) treatment on the clinical metrics of renal function in patients with differentiated thyroid carcinoma (DTC).Patients and methods: The clinical metrics of renal function were analysed in 850 patients with DTC who received 131I therapy between January 2012 and December 2019. According to the baseline renal function metrics, the patients were divided into normal renal function group (group A) and abnormal renal function group (group B). Each group was further divided into three subgroups (subgroups 1, 2, and 3) based on the cumulative dose of 131I. The clinical metrics of renal function including serum creatinine (SCr) levels, blood urea nitrogen (BUN) levels and estimated glomerular filtration rate (eGFR) were measured within 1 month before the initiation of 131I therapy, 1 year after the last therapy, and 5 years after the initial therapy. The changes in renal function metrics before and after 131I therapy were compared in each group.Result: In group A (588 patients), no significant difference in the mean levels of SCr and BUN and eGFR was observed in the three subgroups (P >0.05), regardless of gender, before the initial 131I therapy and 1 year after the last therapy. A total of 8, 3, and 2 patients presented with abnormal renal function after 131I treatment in subgroups 1, 2, and 3, respectively. No statistically significant difference was observed in the incidence of renal dysfunction among the three subgroups (P = 0.287). The mean age of patients with renal dysfunction was significantly greater than that of patients without renal dysfunction after 131I treatment. In group B, of the 262 patients with abnormal renal function, SCr and BUN levels were elevated in 168 and 155 patients, respectively, and eGFR <60 mL/min/1.73 m2 was found in 87 patients before the initial 131I therapy. No significant difference was observed in the parameters among the three subgroups. However, SCr and BUN levels were found to be increased in all subgroups 5 years after the initial 131I therapy, and they were positively correlated with the cumulative dose of 131I. The difference was statistically significant (P <0.05). Furthermore, eGFR was found to be decreased in all subgroups after 131I therapy, and it was negatively correlated with the cumulative dose of 131I. The difference was statistically significant (P <0.05). A gender bias was not observed in the changing trends of SCr and BUN levels and eGFR.Conclusion: Our findings suggest that the nephrotoxicity of high-dose 131I therapy, regardless of gender, is very low in patients with DTC with normal renal function; however, high-dose 131I therapy may exacerbate the loss of renal function in those with renal dysfunction.