For many years the recommended therapy for differentiated thyroid carcinoma (DTC), with the exception of unifocal papillary carcinoma <1 cm in diameter, has consisted of (near) total thyroidectomy followed by postoperative radioiodine ablation of thyroid remnant tissue. Even though results from randomized controlled trials are still missing, this combination has proven its worth as a safe and very effective treatment that resulted in an improved life expectancy and reduced recurrence rate for DTC patients in many observational studies.
Preparation for I-131 ablation using standard activities between 1-3 GBq requires low iodine diet for 2-3 weeks and TSH-stimulation by withdrawal of thyroid hormone medication for 3 weeks following thyroidectomy or by use of recombinant human TSH alternatively. The advantages of exogenous TSH stimulation are a maintained quality of life and a lower radiation dose to the remainder of the body.
In case of metastastic spread, higher activities of radioiodine in the range of 4-11 GBq are necessary; if possible, individual dosimetry is recommended. The standard approach for preparation of I-131 therapy in patients with metastases is endogenous hypothyroidism after thyroid hormone withdrawal.
Indications, contraindications and practical aspects of radioiodine treatment will be discussed in this review.
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