Definition & Overview
A thyroid nodule is an abnormal growth or lump within the thyroid gland. It often develops at the edges of the gland and it either completely solid or filled with fluid. It is considered a common condition, especially among individuals aged 50 years old and older.
The thyroid gland is located in the anterior portion of the neck, found just below the thyroid cartilage of the larynx more commonly known as Adam’s apple among men. It is a major gland in the endocrine system, responsible for several physiological processes. These functions include facilitating the response of the body to other hormones, production of protein, and consumption of energy sources. It also produces the substance that regulates calcium homeostasis. The gland is butterfly-shaped, with two cones connected with a structure called the isthmus.
Thyroid nodule can occur as a single growth or could be in groups or clusters. They are medical classified as cold, warm, and hot. Those attributed as cold nodules are the ones that do not produce any thyroid hormone, while warm nodules produce normal amount of thyroid hormone just like any thyroid cell. Nodules that produce excess amount of hormones are classified as hot nodules.
Cause of condition
There are several medical conditions attributed to the growth of thyroid nodules. A deficiency of iodine levels in the body can lead to the growth of these nodules. This condition is easily avoided, though, as normal inclusion of iodized salt in everyday food preparation is enough to provide adequate level to the body. Iodine deficiency can also lead to the enlargement of the thyroid gland itself, called goiter. This condition can also cause the growth of several thyroid nodules within the goiter itself.
Nodules can also develop as result of a certain autoimmune condition called Hashimoto’s disease or chronic inflammation of the thyroid gland. This can lead to insufficiency in thyroid hormone production or hypothyroidism.
A thyroid nodule is also caused by the transformation of normal thyroid cells into overgrown ones. This condition is also known as thyroid adenoma and can cause an overproduction of the thyroid hormone. A degenerating thyroid adenoma can also lead to the development of fluid-filled cysts that are commonly benign but could sometimes turn malignant.
There are several risk factors that can increase the possibility of developing thyroid nodules. These include age, presence of family history, or previous exposure to radiation in the head or neck area during childhood or early teenage years.
A person who developed a thyroid nodule does not generally exhibit any visible sign or symptom, especially if the nodule is quite small. However, a nodule can become large enough to be visible or felt during routine medical examination. A swelling felt at the base of the neck could indicate a single or cluster of nodules. Sometimes, the growth has become so prominent that it presses against the windpipe and lead to shortness of breath. A nodule could also hinder the function of the esophagus, making it difficult for the afflicted person to swallow food. Some patients also complain of pain in the affected area of the neck and hoarseness of voice.
Hot nodules also produce an overproduction of thyroxine, which is manifested in sudden and unexplained weight loss. This can also cause the patient to suffer tremors, nervousness, intolerance to heat, and irregular heartbeats.
A decreased production of thyroid hormone due to nodule growth is manifested in several ways. Patients experience constipation, feeling of constant weariness or fatigue, brittleness, unexplained weight gain, and inability to stand cold temperature.
Who to see & types of treatments available
If a general medical practitioner would suspect thyroid nodule growth after physical examination, the patient is usually referred to an endocrinologist. This type of physician specializes in all conditions affecting the endocrine system. The endocrinologist will order several diagnostic tests: a thyroid scan and ultrasound, fine needle aspiration, and blood tests to determine levels of thyroid hormones.
If the nodule is determined to be benign, no further treatment is prescribed and the patient is asked to adopt a watch-and-wait strategy. This might entail having regular check-ups and undergoing thyroid function tests from time to time.
Some specialists might prescribe prescription drugs for hormone suppression or anti-thyroid medications, depending on the level of thyroid hormone being produced by the nodules.
A nodule that overproduces hormones may provide enough cause for a patient to start taking radioactive iodine. This substance is taken in liquid or pill forms and is effective in shrinking the most of nodule growths.
If the patient is diagnosed with cancerous thyroid nodules, a surgical option is usually offered. The procedure entails the removal of all nodules and most of the thyroid tissue to prevent further growth. Surgical removal of affected tissue is usually considered the last option, after radioactive and chemotherapy modalities were not effective.
Gharib H, Papini E, Paschke R, et al. American Association of Clinical Endocrinologists, Associazione Medici Endocrinologi, and European Thyroid Association Medical Guidelines for Clinical Practice for the Diagnosis and Management of Thyroid Nodules. Endocr Pract.2010;16(suppl 1):1-43.
Kim M, Ladenson P. Thyroid. In: Goldman L, Schafer AI, eds. Goldman' s Cecil Medicine. 25th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 226.