From the Guidelines
Radioiodine uptake in multiple thyroid nodules typically indicates functioning nodular tissue that may require treatment, and I recommend a complete thyroid evaluation including thyroid function tests (TSH, free T4, free T3), thyroid antibodies, and ultrasound before considering radioiodine therapy. For patients with hyperfunctioning multinodular goiter causing hyperthyroidism, radioiodine treatment with I-131 at doses of 10-30 mCi is often effective, as supported by the American College of Radiology guidelines 1. The exact dose depends on gland size, degree of hyperthyroidism, and patient factors.
Some key points to consider in the management of multiple thyroid nodules include:
- The use of iodine-123 (I-123) is preferred over iodine-131 (I-131) for radionuclide uptake and scan due to its superior imaging quality 1.
- Ultrasound (US) is the best imaging study to evaluate thyroid morphology and can be a helpful adjunct study to a radioiodine uptake scan 1.
- Doppler US may be an alternative to nuclear medicine for separating thyrotoxicosis that is due to an overactive thyroid from thyrotoxicosis due to destructive causes 1.
- Radioiodine ablation is recommended for patients with differentiated thyroid cancer, except for those at very low risk 1.
Patients should discontinue antithyroid medications 3-5 days before treatment and avoid iodine-rich foods and contrast agents for 4-6 weeks prior. After treatment, regular monitoring of thyroid function is essential as hypothyroidism may develop in 20-50% of patients within the first year. This approach is justified because radioiodine selectively accumulates in hyperfunctioning thyroid tissue, delivering targeted radiation that reduces thyroid hormone production. The differential uptake pattern in multiple nodules reflects varying degrees of autonomy among nodules, with some being more functionally active than others. Patients should be informed that complete resolution may require 3-6 months, and some may need a second treatment if hyperthyroidism persists.
From the Research
Radioiodine Multiple Thyroid Nodule Uptake
- Radioiodine uptake is used to assess thyroid function and distinguish between different types of thyroid nodules 2.
- A thyroid scan with 99Tc can be used to distinguish between a solitary hot nodule, a toxic multinodular goitre, or less commonly, thyroiditis or Graves' disease within a coexisting nodular thyroid 2.
- Scintigraphically cold nodules are evaluated in the same way as in the setting of normal or elevated serum TSH levels 2.
- The use of radioiodine in the management of thyroid nodules is not explicitly mentioned in all studies, but it is implied that it may be used in certain cases, such as in the diagnosis and treatment of thyroid cancer 3.
Diagnosis and Management of Thyroid Nodules
- Thyroid nodules are common, being detected in up to 65% of the general population 4.
- Most thyroid nodules are benign, but a small subgroup may harbor a clinically significant cancer, cause compressive symptoms, or progress to functional disease 4.
- The initial management of thyroid nodules includes thyroid function testing and ultrasonographic characteristics, with additional diagnostic procedures such as molecular testing indicated in selected cases 4, 2.
- The American Thyroid Association has developed guidelines for the management of thyroid nodules and differentiated thyroid cancer, including recommendations for initial evaluation, fine-needle aspiration biopsy, and management of benign and malignant nodules 3.
Relevance of Provided Studies
- Studies 4, 2, and 3 provide relevant information on the diagnosis and management of thyroid nodules, including the use of radioiodine uptake.
- Study 5 is not relevant to the topic of radioiodine multiple thyroid nodule uptake, as it discusses the electron microscopy of the morphogenesis of Bacillus subtilis bacteriophage SP3.