Toxic Thyroid Nodules
A thyroid nodule is an abnormal growth or mass within the thyroid, a butterfly-shaped gland that is located in the front of the neck. Fortunately, approximately 95% of these masses are benign.1 However, this does not always mean that their presence will go unnoticed. In fact, a small nodule or even a group of them (typically benign) can start autonomously producing excess thyroid hormone.
As a consequence, the hyperfunctioning nodule(s) can cause the enlargement of the gland (goiter) and a condition known as hyperthyroidism (overactive thyroid). If a single autonomous nodule is involved in this process, it is known as a toxic thyroid nodule or a toxic adenoma. On the other hand, if more than one nodule is involved it is called a toxic multinodular goiter. Importantly, toxic nodular goiter (TNG) is a broader term that encompasses both conditions2
In general, toxic nodular goiter is a very common cause of hyperthyroidism. In fact, after Graves disease, TNG is the second most common cause of hyperthyroidism in the United States.3 Furthermore, this condition is more common in women than in men (older than 40 years), given that the prevalence rate of palpable nodules is 5-7% and 1-2% respectively.2 Also, TNG is especially prevalent in elderly adults. In fact, most patients with this condition are older than 50 years.2
How is it diagnosed?
Patients with a toxic adenoma or a toxic multinodular goiter commonly present with typical signs and symptoms of hyperthyroidism. These clinical findings are usually the first clue for the diagnosis of this condition. However, some patients (mostly elderly) may present with atypical symptoms (i.e. cardiovascular complications) or even none at all (subclinical hyperthyroidism). Most importantly, the diagnosis of hyperthyroidism must be confirmed through laboratory blood tests that show high levels of thyroid hormones and a low level of thyroid-stimulating hormone (TSH). Similarly, these tests can also be used for screening in asymptomatic patients.4
Nuclear medicine thyroid scans are usually performed to determine the cause of hyperthyroidism. In essence, these imaging studies use radioactive drugs (iodine-123 or technetium-99m) to assess the functioning of thyroid tissue. For instance, they can detect if there are any areas of the thyroid that are overactive, meaning that they have an abnormally high uptake of the drug. In scan results, a toxic adenoma can appear as a single hyperfunctioning area, whereas a toxic multinodular goiter usually appears as multiple overactive areas (patchy appearance).4 Finally, other imaging modalities, like ultrasonography, can be used to assess and monitor thyroid nodules.
The goal of treatment for TNG is the rapid and long-lasting elimination of the state of hyperthyroidism. The most common treatment options for hyperthyroidism are antithyroid drugs, radioiodine therapy, and surgery. Additionally, minimally invasive procedures, such as radiofrequency ablation (RFA), have also become available.4 The choice of treatment for TNG will depend on the severity of the hyperthyroidism, coexisting conditions, the presence of contraindications for specific treatment modalities, and the patient’s preferences. 4
In the treatment of toxic nodules, antithyroid drugs can be prescribed to treat hyperthyroidism. Moreover, beta-blockers can also help diminish hyperthyroidism-related symptoms (i.e. increased heart rate), if present.2 However, these drugs are only useful to temporarily control thyroid hormone production and prevent complications. Given that if this type of treatment is suspended the hyperthyroidism reappears, these medications are more of a bridge to definite therapy as opposed to a final solution for TNG. 2 Additionally, antithyroid drugs can also help control hormone production in preparation for definitive treatments such as surgery or radioactive iodine therapy.
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Radioiodine therapy is widely used as a definitive treatment for toxic adenoma and toxic multinodular goiter. In fact, it is the most widely used treatment for toxic nodules in the United States.5 This therapy is based on the fact that the thyroid gland takes up almost all the iodine in the body. Thus, when radioactive iodine (I-131) is administered it can accumulate in the overactive gland tissue and destroy it. As a result, toxic nodules can decrease in size and the signs and symptoms of hyperthyroidism can subside (usually within 2-3 months).
Notably, a single dose of this therapy has been shown to reduce goiter size by up to 40% and it usually succeeds in 85-100% of patients with toxic nodular goiter.2 However, a complication known as hypothyroidism (underactive thyroid) can occur in up to 10-20% of patients.2
Possible indications for radioiodine therapy include advanced age, small goiter size, significant coexistent diseases, and prior surgery or scarring of the anterior neck.4 Furthermore, the main contraindications for this procedure are pregnancy, lactation, and coexisting thyroid cancer.4 Importantly, high activity radioiodine therapy can only decrease the size of large goiters by 30-50% and improve compressive symptoms in 46% of the patients. Whereas complete surgical removal of the thyroid achieves a complete resolution of these symptoms in all patients.4
Thyroid surgery is one of the definitive treatments for toxic nodules. A thyroidectomy, or the surgical removal of all or part of the gland, might be necessary if other treatments are inappropriate or contraindicated. Possible indications for surgery include signs and symptoms of excessive pressure in the neck by an enlarged thyroid (i.e. difficulty swallowing or breathing), concern for thyroid cancer, failure of radioiodine therapy, and the need for a rapid resolution of the thyrotoxic state (life-threatening condition induced by excessive thyroid hormone secretion).4
Generally, the presence of a toxic adenoma will involve the removal of the entire thyroid lobule that has the lesion. Conversely, a total or near-total thyroidectomy is typically performed if nodules are on both sides of the thyroid (i.e. toxic multinodular goiter). Most importantly, the risk of treatment failure after either procedure is <1%.4 However, there are several important complications of surgery and some can be dependent on the extent of the procedure (i.e. hypothyroidism or underactive thyroid, hypoparathyroidism, vocal cord paralysis).2
Non-Surgical RFA for Toxic Thyroid Nodules
Promising minimally invasive procedures are available for patients with toxic thyroid nodules. For instance, if long-term medical treatment, surgery, or radioiodine therapy are inappropriate or contraindicated in patients with this condition, a procedure known as radiofrequency ablation (RFA) can be considered as an alternative.4
Radiofrequency Ablation (RFA) is performed by trained interventional radiologists and it uses high-frequency alternating current to create focalized heat and destroy tissue. In TNG, an ultrasound-guided needle electrode is used to specifically target and eliminate the activity of toxic nodules.
A large retrospective multicenter study validated the safety and efficacy of this procedure for treating autonomously functioning nodules. It demonstrated that associated hyperthyroidism improved in all subjects and normalized in 81.8%. Additionally, no hypothyroidism or major complication was noticed during follow-up.6 Similarly, in another study, RFA was compared to surgery in the treatment of nontoxic nodules. It had fewer complications (1% for RFA and 6% for surgery), no resulting hypothyroidism, similar costs to surgery, and an 85% reduction in nodule size.7
Despite promising evidence, additional large scale studies are needed in patients with toxic thyroid nodules before it can be recommended as mainstream.4 Finally, given the complexity of the procedure, the use of RFA should be limited to experienced clinicians that have received extensive training in this technique.
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Request a consultation to meet with our varicocele specialist who will review your imaging, labs and history to determine if you are candidate for the procedure, and the outcomes you can expect. Each person is an individual and should discuss the potential risks and benefits of embolization and other treatments with our doctor to decide which option is best.
Consultations are available via an online video telehealth platform or in person at one of the offices in Los Angeles, Orange County or San Diego. Why should you choose us? Read here
1.) Hegedüs, L. (2004). The thyroid nodule. New England Journal of Medicine, 351(17), 1764–1771. https://doi.org/10.1056/nejmcp031436
2.) Philip R Orlander, M. D. (2021, June 14). Toxic nodular goiter. https://emedicine.medscape.com/article/120497-overview#a4.
3.) Vanderpump, M. P. (2011). The epidemiology of thyroid disease. British Medical Bulletin, 99(1), 39–51. https://doi.org/10.1093/bmb/ldr030
4.) Ross, D. S., Burch, H. B., Cooper, D. S., Greenlee, M. C., Laurberg, P., Maia, A. L., Rivkees, S. A., Samuels, M., Sosa, J. A., Stan, M. N., & Walter, M. A. (2016). 2016 American Thyroid Association guidelines for diagnosis and management of hyperthyroidism and other causes of thyrotoxicosis. Thyroid, 26(10), 1343–1421. https://doi.org/10.1089/thy.2016.0229
5.) Kravets, I. (2016, March 1). Hyperthyroidism: Diagnosis and treatment. American Family Physician. https://www.aafp.org/afp/2016/0301/p363.html#afp20160301p363-b2.
6.) Sung, J. Y., Baek, J. H., Jung, S. L., Kim, J.-hoon, Kim, K. S., Lee, D., Kim, W. B., & Na, D. G. (2015). Radiofrequency ablation for Autonomously Functioning Thyroid Nodules: A Multicenter Study. Thyroid, 25(1), 112–117. https://doi.org/10.1089/thy.2014.0100
7.) Che, Y., Jin, S., Shi, C., Wang, L., Zhang, X., Li, Y., & Baek, J. H. (2015). Treatment of benign thyroid nodules: Comparison of surgery with radiofrequency ablation. American Journal of Neuroradiology, 36(7), 1321–1325. https://doi.org/10.3174/ajnr.a4276
The above information explains what is involved and the possible risks. It is not meant to be a substitute for informed discussion between you and your doctor, but can act as a starting point for such a discussion.