Long-term outcomes of renal function after radioactive iodine therapy for thyroid cancer according to preparation method: thyroid hormone withdrawal vs. recombinant human thyrotropin

Long-term effects of iatrogenic hypothyroidism on renal function from thyroid hormone withdrawal during radioactive iodine therapy (RAIT) have not been studied, especially in subjects with mildly impaired renal function. We compared renal function in thyroid cancer subjects according to preparation method of either thyroid hormone withdrawal (THW) or injection of recombinant human thyrotropin (rhTSH).

This retrospective study enrolled 241 thyroidectomized patients (rhTSH group, n = 87 and THW group, n = 154). Changes in glomerular filtration rate (GFR) were measured prior to surgery, at the time of RAIT, and during a regular follow-up at least one year after RAIT.

Baseline renal function was comparable between the rhTSH group and the THW group (91.4 mL/min/1.73 m² vs. 92.4 mL/min/1.73 m²). At the time of RAIT, GFR was significantly decreased in the THW group (70.6 mL/min/1.73 m², -23.6%), whereas renal function was preserved in the rhTSH group (85.4 mL/min/1.73 m², -6.6%). In the THW group, renal function was fully recovered within 6 months after RAIT and was maintained up to 24 months, even in subjects with baseline GFR less than 90 mL/min/1.73 m².

THW for RAIT preparation induced considerable reduction in renal function, but this change was transient. In contrast, injection of rhTSH did not decrease renal function, making it a good option for RAIT preparation for subjects with renal dysfunction.