Most thyroid nodules are small and cause no issues. These nodules might be seen on a neck ultrasound or another medical scan undertaken for unrelated reasons but they will not be otherwise noticeable.
Larger nodules can cause several symptoms. Typically pressure, tightness or discomfort in the neck, an unpleasant awareness or difficulty in swallowing and possibly shortness of breath, which can be worse on lying flat. A hoarse or changed voice is also possible and might be due to pressure on the nerve supplying the voice box or vocal cords (the recurrent laryngeal nerve). Large nodules can also be distressing from a cosmetic perspective.
Most nodules are inactive (they do not produce any thyroid hormone). However a proportion will secrete thyroid hormone independently and outside of the body’s usual control mechanism (see How does the thyroid gland work?). Because these nodules function alone they are called autonomously functioning thyroid nodules (AFTN). AFTN can be ‘sub-clinical’ (thyroid hormone in the blood remains normal) and there are no symptoms related to the AFTN; these nodules are diagnosed through thyroid function blood tests with low TSH (thyroid stimulating hormone) levels. Alternatively they can be clinically evident (thyroid hormone is elevated in the blood and a patient will be aware of the excess thyroid hormone production). Symptoms related to excessive thyroid production (hyperthyroidism) include palpitations (awareness of a rapid heartbeat), an anxious ‘edgy’ feeling, sweating, tiredness, and more frequent or loose bowel motions.
