Systemic absorption of Tc-99m-pertechnetate during dacryoscintigraphy: a note of caution.

We report a 37-year-old patient with the history of bilateral epiphora, who was referred to our department for dacryoscintigraphy imaging. The patient had bilateral obstruction of the lacrimal apparatus at the sac-duct level on the scintigraphy images. Delayed imaging showed Tc-99m pertechnetate uptake in the thyroid due to systemic absorption of the tracer from the conjunctiva. We recommend using tracers with large particle size and lower possibility of mucosal absorption for dacryoscintigraphy in order to decrease unnecessary thyroid radiation.