What is the management of toxic multinodular goiter (TMNG)?

From the Guidelines

Toxic multinodular goiter is best treated with radioactive iodine (RAI) therapy or thyroidectomy, depending on individual factors. For RAI therapy:

• Typical dose: 10-30 mCi of I-131
• Patient should avoid iodine-rich foods and medications for 1-2 weeks before treatment
• Expect resolution of hyperthyroidism within 2-6 months For thyroidectomy:
• Total or near-total thyroidectomy is recommended
• Preoperative preparation with antithyroid drugs (e.g., methimazole 10-30 mg daily) for 2-3 months to achieve euthyroidism
• Beta-blockers (e.g., propranolol 20-40 mg 3-4 times daily) may be used to control symptoms Post-treatment, patients will require lifelong thyroid hormone replacement (typically levothyroxine, starting dose 1.6 mcg/kg/day) 1. The choice between RAI and surgery depends on factors such as goiter size, patient age, comorbidities, and preference, as noted in the acr appropriateness criteria for thyroid disease 1. Toxic multinodular goiter involves multiple autonomously functioning nodules producing excess thyroid hormone, and treatment aims to reduce hormone production and relieve compressive symptoms if present. Ultrasound (US) can be a helpful adjunct study to a radioiodine uptake, as it can evaluate thyroid morphology and confirm the presence of nodules, as well as evaluate for suspicious features of malignancy 1. Doppler US may also be an alternative to nuclear medicine for separating thyrotoxicosis that is due to an overactive thyroid from thyrotoxicosis due to destructive causes, although radionuclide uptake studies are still preferred 1. Radionuclide uptake and scan can confirm that the entire goiter consists of thyroid tissue, and Iodine-123 (I-123) is preferred over iodine-131 (I-131) because of its superior imaging quality 1. In a multinodular goiter, the scan should be compared to an US to identify hypofunctioning or isofunctioning nodules to be targeted for biopsy 1.

From the FDA Drug Label

Methimazole tablets, USP are indicated: In patients with Graves’ disease with hyperthyroidism or toxic multinodular goiter for whom surgery or radioactive iodine therapy is not an appropriate treatment option. The management of toxic multinodular goiter (TMNG) includes:

• Methimazole for patients for whom surgery or radioactive iodine therapy is not an appropriate treatment option 2
• Preparation for thyroidectomy or radioactive iodine therapy to ameliorate symptoms of hyperthyroidism 2

From the Research

Management of Toxic Multinodular Goiter (TMNG)

The management of TMNG can be achieved through various methods, including:

• Radioiodine therapy: This is a common treatment option for TMNG, as it is simple, safe, and effective for most patients 3, 4, 5.
• Surgery: Surgical excision is preferred for patients with large goiters, local compression symptoms, or concern about malignancy 6.
• Antithyroid drugs: Long-term, low-dose methimazole (MMI) treatment can be a safe and effective method for treating TMNG, especially for patients who are not suitable for radioiodine therapy or surgery 7.

Treatment Outcomes

The outcomes of these treatment methods are as follows:

• Radioiodine therapy: This treatment can cure 78-92% of patients with TMNG, with 41-52% becoming euthyroid after treatment 3, 4, 5.
• Surgery: Surgical excision can effectively treat TMNG, especially for patients with large goiters or local compression symptoms 6.
• Antithyroid drugs: Long-term MMI treatment can maintain euthyroidism in 96% of patients, with few side effects 7.

Considerations for Treatment

When choosing a treatment method, the following factors should be considered:

• Goiter size and extent: Large goiters may require surgical excision, while smaller goiters can be treated with radioiodine therapy or antithyroid drugs 6.
• Thyroid function: Patients with hyperthyroidism may require radioiodine therapy or antithyroid drugs, while those with normal thyroid function may be monitored with yearly evaluations 6.
• Patient age and health status: Older patients or those with comorbidities may be more suitable for radioiodine therapy or antithyroid drugs, while younger patients may be more suitable for surgery 6.