What Are Thyroid Nodules?
Thyroid nodules are more common than you probably think. By the age of 60, 50% of all people have them. We’re going to answer a few of the commonly asked questions about thyroid nodules.
What are thyroid nodules?
To start, the thyroid gland is a fluid-filled or solid lump that develops on the airway in the lower neck. The thyroid gland produces the thyroid hormone, which helps to control many of the body’s metabolic functions. A thyroid nodule is an abnormal collection of cells within the thyroid gland and can present as a lump or bump in the lower neck. They can typically be felt during a general physical exam. Thyroid nodules are very common, with up to 50% of people developing thyroid nodules during their lifetime.
Different types of thyroid nodules
Nodules which are small in size and located some distance from sensitive structures such as the trachea are often asymptomatic (meaning patients don’t feel them and they cause no health issues), they may not even be noticed. Nevertheless, some thyroid nodules can cause symptoms like shortness of breath or – only in the case of hot nodules – hyperthyroidism
Benign nodules are classified based on their ability to produce hormone in comparison to healthy thyroid tissue. They are differentiated into three categories: hot, cold and indifferent (or “normal”) nodules. Hot nodules are more active than regular thyroid tissue and therefore produce more hormones in comparison. On the other hand, cold nodules are lumps of tissue without any real ability to produce thyroid hormones compared to regular thyroid tissue. Lastly, normal or indifferent nodules cannot be differentiated from healthy tissue based on their hormone producing ability. Most thyroid nodules are cold nodules (approx. 50-85%), whilst only 10% of nodules are “hot” and about 40% are indifferent3.
What are the symptoms of thyroid nodules?
Many thyroid nodules do not cause symptoms. Very large cases can cause compression on surrounding structures in the neck, which can sometimes lead to changes in swallowing or breathing. If the nodule is producing an excess of thyroid hormones, it is possible to develop symptoms of hyperthyroidism. Those can be rapid/irregular heartbeat, unexplained weight loss, muscle weakness, trouble sleeping, and nervousness. That being said, most thyroid nodules are non-functioning in nature. Often times, thyroid blood tests are normal in patients with nodules.
Most thyroid nodules appear as bumps in the lower neck, so they can be felt or seen in the mirror. If you suspect you have thyroid nodules, consult your doctor.
What are the differences between hot, warm and cold nodules?
Hot, warm, and cold are the three ways that thyroid nodules are classified. Nodules that produce excess thyroid hormone are classified as hot nodules. If they are non-functioning and appear as holes in the scan, they are cold nodules. A warm thyroid nodule is producing a normal amount of hormone. 85% of cold nodules, 90% of warm nodules, and 95% of hot nodules are benign.
Symptoms of cold and indifferent nodules
Cold and indifferent nodules are often asymptomatic due to their size, small enough not to be seen without imaging tests. In the US, only 4-7% of the adult population have palpable lumps, whereas detectable lumps, found with ultrasound, occur in more than 50% of the population above the age of 60. Nevertheless, if cold and indifferent nodules grow they can cause discomfort and problematic symptoms by exerting pressure on sensitive structures in the neck. Commonly reported symptoms in those cases include a feeling of compression, voice changes as well as difficulty breathing or swallowing.
Symptoms of hot nodules
Due to their increased hormone producing ability, hot nodules can cause significant metabolic imbalance and dysregulation of various processes in the body. As long as these nodules remain small effects may not be serious, however, excessive hormone overproduction can lead to the development of hyperthyroidism. Symptoms of hyperthyroidism include anxiety, restlessness, tremors, agitation, sweating, unusual weight loss and increased heart rate amongst others. In extreme cases, the effects of disease can even become life-threatening. Especially amongst, older people who are at risk of experiencing irregular heart rhythms and even heart failure in cases of extreme and untreated hyperthyroidism
How are thyroid nodules diagnosed? And how can it be treated?
Thyroid nodules are typically evaluated by thyroid ultrasound, which allows the endocrinologist to tell if it is cancerous or not. Based on the findings of the ultrasound, the American Thyroid Association has recommendations to guide physicians as to when additional workup of the nodules is needed. This can include fine needle aspiration biopsy or thyroid surgery. Biopsies are usually performed in the office, with ultrasound guidance. Thyroid biopsy results are classified into categories based on the appearance of the cells when viewed under a microscope. Ultimately, this classification system (the Bethesda System for Reporting Thyroid Cytopathology) will help you and your doctor decide whether your nodules can continue to be monitored with ultrasound, or whether additional testing or surgery is necessary. Treatment options will be determined by the size and type of thyroid nodule. Your endocrinologist may even decide not to treat it in the case that the nodule is not cancerous and is not causing problems. To be safe, your doctor may perform occasional biopsies even if the nodule started out as benign.
Despite the vast majority of lumps in the thyroid being non-cancerous, early diagnosis is of high importance to clearly classify a nodule and rule out any risks of malignancy. Moreover, diagnostic tools help to recognize different types of nodules (hot, cold or indifferent) in order to decide upon the most suitable treatment regimen. A scintigraphy (nuclear thyroid scan) is a commonly used tool to classify thyroid nodules5.
Various treatment options are available. Whilst surgical excision and radioactive iodine treatment are still common and remain the gold standard for cancer, less invasive treatment methods are available for non-cancerous lumps. These include minimal-invasive thermal ablation options such as laser ablation, microwave ablation (MWA) or radiofrequency ablation (RFA) as well as the non-invasive Echotherapy.
References
https://www.cancer.gov/publications/dictionaries/cancer-terms/def/hot-nodule
https://echotherapie.com/thyroid-nodules/what-are-hot-and-cold-thyroid-nodules/
https://www.mmclinic.com/www/blog/viewpost/216#:~:text=Nodules%20that%20produce%20excess%20thyroid,of%20hot%20nodules%20are%20benign.
