What is the diagnosis and treatment for Multinodular Goiter (MNG)?

From the Guidelines

Multinodular goiter (MNG) should be diagnosed and treated based on symptoms and risk factors, with asymptomatic patients undergoing observation and regular follow-up, while those with compressive symptoms or cosmetic concerns requiring treatment with medical therapy, radioactive iodine, or surgery. The diagnosis of MNG involves confirming the presence of a goiter and documenting its size and extent, as well as assessing for obstructive symptoms, which can be achieved through imaging studies such as ultrasound (US) 1. US is the best imaging study to evaluate thyroid morphology and can be a helpful adjunct study to a radioiodine uptake, and it can also confirm the presence of nodules and evaluate for suspicious features of malignancy 2. Management of MNG depends on symptoms and risk factors, with medical therapy including levothyroxine (typically starting at 50-100 mcg daily, adjusted based on TSH levels) for patients with subclinical hypothyroidism, and radioactive iodine (I-131) may be used for hyperfunctioning nodules, typically as a single dose of 10-30 mCi. Some key points to consider in the management of MNG include:

• Surgery (total or partial thyroidectomy) is recommended for large goitres causing compression, suspicious nodules, or failed medical management 1.
• Post-surgery, patients often require lifelong thyroid hormone replacement.
• Fine-needle aspiration biopsy should be performed for dominant or suspicious nodules to rule out malignancy.
• Multinodular goitres develop due to genetic factors, iodine deficiency, or environmental influences that cause irregular thyroid cell growth and function, leading to areas of hyperplasia and nodule formation within the gland. It is essential to prioritize the patient's symptoms and risk factors when determining the best course of treatment for MNG, and to use the most recent and highest quality evidence to guide decision-making, such as the studies published in the Journal of the American College of Radiology 1, 2.

From the FDA Drug Label

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 diagnosis of Multinodular Goiter (MNG) is not directly addressed in the provided drug label. However, the treatment for toxic multinodular goiter is mentioned, which includes:

• Methimazole as an option for patients for whom surgery or radioactive iodine therapy is not appropriate 3
• Surgery as a treatment option
• Radioactive iodine therapy as a treatment option The provided label does not give information on the diagnosis of MNG.

From the Research

Diagnosis of Multinodular Goiter (MNG)

• The diagnostic evaluation of patients with MNG consists of clinical evaluation, biochemical testing, fine-needle aspiration (FNA), and imaging studies 4.
• The serum TSH level is a sensitive and reliable index of thyroid function 4.
• FNA results are pivotal to assess cancer risk in patient management for prominent palpable and suspicious nodules 4.
• Imaging studies such as chest radiography, high-resolution ultrasonography, and computed tomography help to delineate the size and extent of a goiter in evaluating compression symptoms 4.

Treatment of Multinodular Goiter (MNG)

• Indications for treatment in patients with MNG include hyperthyroidism, local compression symptoms attributed to the goiter, cosmesis, and concern about malignancy based on FNA results 4.
• The use of levothyroxine suppression therapy to effectively decrease and control MNG size is controversial 4.
• Thyroid hormone should not be used, however, in patients with suppressed serum TSH levels, to avoid the development of toxic symptoms 4.
• Management of toxic MNG by surgery is well established 4, 5.
• Radioiodine is also effective therapy for many of these patients 4, 5, 6, 7.
• For patients with nontoxic MNG, surgical excision is preferred when treatment is necessary 4, 8, 6.
• Radioactive iodine may be a reasonable option for many patients with nontoxic MNG 8, 6, 7.
• Long-term, low-dose methimazole treatment is a safe and effective method for treatment of toxic MNG, and is not inferior to radioiodine treatment 7.

Treatment Options for Toxic Multinodular Goiter (TMNG)

• Radioiodine (RAI) and long-term methimazole (MMI) treatment are effective options for TMNG 7.
• RAI treatment can result in hypothyroidism, persistence or recurrence of hyperthyroidism, or euthyroidism 7.
• Long-term MMI treatment can result in subclinical hypothyroidism, but is generally safe and effective 7.
• The dosage of MMI to maintain euthyroidism may need to be adjusted over time 7.