To detect whether the adverse effects of post-operative radioactive iodine therapy following differentiated thyroid cancer on smell, taste and nasal functions were associated with radioactive iodine dose.

Fifty-one patients who had undergone total thyroidectomy because of differentiated thyroid cancer were divided into two groups depending on the post-operative radioactive iodine therapy dose: low dose group (50 mCi; 21 patients) and high dose group (100–150 mCi; 30 patients). The Sniffin’ Sticks smell test, the Taste Strips test and the 22-item Sino-Nasal Outcome Test were performed on all patients one week before therapy, and at two months and one year following therapy.

Statistically significant differences were detected in the Sniffin’ Sticks test results, total odour scores, total taste scores and Sino-Nasal Outcome Test results between the assessment time points. There was no statistically significant difference between the low and high dose groups in terms of odour, taste or Sino-Nasal Outcome Test scores either before or after therapy.

Radioactive iodine therapy has some short- and long-term adverse effects on nasal functions and taste and odour sensations, which affect quality of life. These effects are not dose-dependent.