Preoperative contrast-enhanced computerized tomography should not delay radioiodine ablation in differentiated...

There is concern about potential interference of iodinated contrast used in contrast-enhanced computerized tomography (CECT) with radioiodine therapy in differentiated thyroid carcinoma (DTC). The aim of this study was to determine the effect of iodinated contrast on urinary iodine concentration (UIC) in patients having thyroidectomy compared with control groups without CECT and without thyroidectomy.

This prospective control study consisted of 4 groups each comprising 32 patients. Group 1- DTC patients undergoing preoperative CECT, group 2- DTC patients not undergoing CECT, group 3- benign goiter patients undergoing preoperative CECT, and group 4- patients with non-thyroidal diseases undergoing preoperative CECT. Spot UIC before CECT, after surgery (5-7 d), and at follow-up (4-6 wk) were compared among the groups.

The median basal UIC levels were not significantly different between the four groups (232.2 versus 263.9 versus 268.2 versus 178.2 μg/L, respectively, P = 0.443). In contrast, groups having preoperative CECT had significantly higher UIC levels at discharge (924 versus 329 versus 776 versus 661 μg/L, respectively, P = 0.001). These differences became insignificant at follow-up (225 versus 252 versus 310 versus 275 μg/L, respectively, P = 0.505). Patients having follow-up UIC values above the conventional cut-off of clinically relevant iodine excess (>200 μg/L) also had significantly higher basal values than those having lower follow-up values (283.0 versus 181.7 μg/L; P = 0.037).

Irrespective of the fact whether a patient is thyroidectomized or not preoperative CECT using non-lipophilic contrast does not result in long-term iodine retention.