The thyroid is a small gland located at the base of the neck, in the front. The thyroid controls many functions of the organism through the production of thyroid hormones: thyroxine (T4) and triiodiothyronine (T3) (Video). The production of thyroid hormones is, in turn, controlled by the "thyroid stimulating hormone (TSH) secreted by" pituitary, a gland located inside the skull. Thyroid hormones regulate important body functions, including breathing, heart rate, body temperature, central nervous system development and body growth (Video).
Nodules of the thyroid gland are solid, or fluid-filled, formations that form inside the gland itself and represent the most frequent thyroid disease. Nodules are almost always benign formations and only in 0.3% of cases have characteristics of malignancy (thyroid tumors).Symptoms
Thyroid nodules usually cause no symptoms. Occasionally, however, some become so large that they are bothersome, creating a lump at the base of the neck or causing shortness of breath and difficulty swallowing.
Sometimes the nodules produce thyroid hormones and can, therefore, cause the typical disorders of over-functioning of the gland (hyperthyroidism): unexplained weight loss, tremor, nervousness, sleep disturbances, rapid or irregular heartbeat and heat intolerance.
Thyroid nodules with features of malignant tumors are slow growing and may be small in size when discovered. There are, however, aggressive and fast-growing thyroid cancers, but they are rare.
The chances of a lump being malignant are slim but there are some things that can make it suspicious:
- family members with thyroid problems or other endocrine gland tumors
- age under 30 or over 60 years
- male gender
- radiation exposure, especially in the head and neck
A large, hard, or painful lump is of more concern in terms of malignancy.Causes
The development of nodules has been associated with several conditions:
- iodine deficiency in the diet
- overgrowth of normal thyroid tissue (thyroid adenoma): is not considered serious unless it causes symptoms
- thyroid tumors: the chances of a thyroid nodule being malignant are low; however, the risk is higher if you have family members with thyroid disease
In evaluating a thyroid nodule it is essential to first exclude the possibility that it is tumors and then evaluate the functionality of the thyroid. Therefore, the following checks may be required:
- measurement of the levels in the blood of the hormones produced by the thyroid gland (T4 and T3) and of the hormone that regulates it (TSH)
- ultrasound, to get information about the size and structure of the nodules and to distinguish cysts from solid nodules
- fine needle aspiration, to distinguish between benign and malignant thyroid nodules
- scintigraphy, for useful information on the structure and function of the thyroid gland. The test consists of injecting a small amount of radioactive (iodine or technetium) into a vein, which accumulates in the thyroid. The thyroid can, therefore, be studied using a special machine. With this test, you can distinguish warm lumps (which produce excessive amounts of hormones and are almost always benign) and cold lumps that do not produce hormones but can be malignant. The disadvantage of scintigraphy is that it cannot distinguish between benign (more frequent) and malignant cold nodules
Treatment of nodules depends on their nature.
Benign thyroid nodule
It may be sufficient to keep it under control with blood tests, to evaluate the functioning of the thyroid gland and with ultrasound, to be carried out once a year. If the lump remains unchanged, no treatment may be needed.
In some cases, thyroid hormone T4 (levothyroxine) therapy may be prescribed to cause the pituitary gland to produce less TSH, a hormone that stimulates the growth of thyroid tissue.
Occasionally, even a benign lump may require surgery, especially if it is so large that it is difficult to breathe or swallow.
Nodules causing hyperthyroidism
If thyroid nodules produce thyroid hormones, Treatment for hyperthyroidism is recommended, which includes:
- radioactive iodine, a form of radiation therapy used to treat most types of overactive thyroid. The radioactivity dose of the administered iodine is very low and is not harmful. Taken by mouth, radioactive iodine is absorbed by the thyroid and causes a reduction in the production of thyroid hormones and in the volume of the gland. Symptoms of hyperthyroidism usually subside within three to six months. The risk of radioactive iodine treatment is that thyroid hormone production becomes too low causing hypothyroidism
- anti-thyroid drugs (thionamides), thionamides reduce the synthesis of thyroid hormones by preventing the transformation of the form of iodine circulating in the organism (iodine iodide) into that which is used for the production of thyroid hormones (free iodine). In this way they are gradually reduced the symptoms of hyperthyroidism, which usually begin to improve between six and twelve weeks after the start of treatment. Generally, therapy must be continued for at least a year. In some cases the problem is resolved in a way definitive; in others, there may be a relapse. However, these drugs can cause liver and bone marrow problems and, therefore, should be used with caution and regular checks
- beta blockers: are drugs commonly used to treat hypertension which can limit the cardiac symptoms of hyperthyroidism by controlling heart rate. Beta blockers can cause some side effects, including feeling tired, cold hands and feet, and difficulty sleeping. They are not usable in case of asthma
- surgery: surgery (thyroidectomy) is used when other treatments are not possible, for example, in pregnancy, or in the presence of a large goiter, or if a relapse occurs after therapy with anti-thyroid drugs, or in the case of eye disorders for Graves' disease. Surgery consists in the removal of all or a large part of the thyroid. The risk of surgery may be damage to the parathyroid glands, which help control calcium levels in the blood, or a lesion of the vocal cords, with alteration of the voice. life thyroid hormone T4 (levothyroxine)
In the case of malignant thyroid nodules, surgery (thyroidectomy) is used to remove all or most of the thyroid. Most thyroid cancers diagnosed early on have a good chance of recovery.Bibliography
Higher Institute of Health (ISS). National Congenital Hypothyroid Registry (RNIC)
Higher Institute of Health (ISS). National Observatory for the Monitoring of Iodoprophylaxis in Italy (OSNAMI)In-depth link
Ministry of Health. Iodine and health