Nasolacrimal Duct Obstruction following Radioactive Iodine: An update on counseling recommendations for thyroid cancer survivors.

Objective: Radioactive Iodine treatment for thyroid carcinoma may induce nasolacrimal duct obstruction. Evidence-based recommendations regarding nasolacrimal screening and prophylactic management in thyroid cancer survivors are lacking.

Methods: A case control study of patients treated with radioactive iodine for thyroid carcinoma was performed, comparing those who developed symptomatic nasolacrimal duct obstruction (Group 1) to age- and gender-matched controls who did not develop nasolacrimal duct obstruction (Group 2), to identify risk factors.

Results: Fifty patients with history of radioactive iodine treatment for thyroid carcinoma were reviewed, including 25 patients who subsequently developed epiphora and were diagnosed with nasolacrimal duct obstruction, and 25 age and gender-matched RAI-treated patients who did not develop nasolacrimal duct obstruction. The mean cumulative RAI dose was 223.4 mCi (8.27 Gbq) for Group 1 and 121.4 mCi (4.49 Gbq) for Group 2 (p = 0.0092). The mean initial treatment dose was 128.9 mCi (4.77 Gbq) and 100.0 mCi (3.70 Gbq) for the two groups, respectively (p = 0.0317). The mean number of radioactive iodine treatment sessions in patients who developed nasolacrimal duct obstruction was 1.48 (range 1-3), compared to 1.16 (range 1-2) in the group that did not (p = 0.0387).

Conclusions: Higher initial and cumulative treatment dose of radioactive iodine, and multiple treatment sessions, increased likelihood of subsequent development of nasolacrimal duct obstruction. We recommend increased counseling and screening of thyroid cancer survivors undergoing radioactive iodine for thyroid carcinoma at lower doses than previously indicated, particularly in those who undergo multiple treatment sessions.