Correlation between cervical uptake and results of postsurgical radioiodine ablation in patients with thyroid...

The objective of this study was to determine the relationship between cervical uptake after thyroidectomy and the success of treatment of cervical remnants with high-dose radioiodine (100 mCi).

Cervical uptake was retrospectively analyzed after total thyroidectomy and before treatment with radioactive iodine in 142 patients seen at our service who received 100 mCi iodine-131 and whose posttreatment scan only showed cervical uptake without distant metastases. The patients were divided into 5 groups according to the uptake result obtained before ablative therapy.

Successful treatment, defined as stimulated thyroglobulin levels <5 ng/mL and a clean scan or only discrete cervical uptake (0.5%) 6 months to 1 year after surgery, was obtained as follows: patients with uptake <1% (n = 48) showed 95.8% treatment efficacy, those with uptake of 1-2% (n = 32) 94% efficacy, and those with uptake of 2-5% (n = 30) reached 83% success, whereas patients with uptake of 5-10% (n = 20) presented 70% efficacy, and treatment was successful in only 50% of patients with uptake >10% (n = 12).

Postoperative measurement of cervical I-131 uptake could be a reasonable predictor of the success of the remnant ablation, and perhaps a guide in deciding the ablative dose of I-131, based on the inverse correlation between the uptake and ablation efficacy.