Abstract
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Objectives Following thyroidectomy, patients with well differentiated thyroid cancer routinely receive I-123 NaI for radiodine neck uptake measurements (RAIU) prior to I-131 ablation. The study's goal was to identify patient specific predictors of RAIU.
Methods 201 patients received 1-3 mCi I-123 NaI po, & imaged at 24 hour for RAIU measurement. Patient prep for RAIU was either Thyrogen injection (n=126) or thyroid hormone withdrawal (n=75). Patient age, weight (wt), operating surgeon, thyroid weight and TSH were recorded. Univariate & mulitiple variate analysis was performed.
Results 201 patients were treated by 6 surgeons. The mean patient age was 51.6 years; with median patient wt 79 kg. The median wt of surgically removed thyroids was 18.4 gm. The mean TSH level was 91.3uU/mL. There was a weak but significant correlation between patient wt & wt of the surgically removed thyroids (p=0.46). The median RAIU was 0.35%, with 25% of patients having RAIU ≤ 0.15% & 25% of patients having RAIU ≥ 1.3%. Patients receiving a Thyrogen injection had significantly lower RAIU values than patients undergoing thyroid hormone withdrawal (p<0.001). Patients who underwent thyroidectomy by the non-endocrine surgeon had significantly higher RAIU values (p=0.017). Patients with higher levels of TSH had higher RAIU values (p=0.030). Patients with greater body wts had lower RAIU values (p=0.088). There was no association between patient age & RAIU (p=0.748) or between the resected thyroid wt & RAIU (p=0.387).
Conclusions TSH levels, patient’s wt and operating surgeon were identified as significant predictors of post thyroidectomy RAIU. Patient’s age and resected thyroid wt were not predictors of post thyroidectomy RAIU.
Results of Univariate Analysis