The thyroid gland consists of two lobes that look similar to the wings of a butterfly. The thyroid is able to absorb iodine from food you consume. It is the only gland in your body that can do this. Your thyroid takes the iodine and uses it to produce two main hormones, triiodothyronine also known as T3 and thyroxine known as T4. These are the hormones that regulate the rate that your body uses carbohydrates and lipids or fats. The thyroid also helps control body temperature, heart rate, as well as the creation of proteins. Calcitonin, yet another hormone the thyroid manufactures, is a hormone that regulates calcium level in the blood.
Though we have no definitive knowledge as to the cause of most nodules and their onset, it has been found that there a certain factor that are associated with the onset. The list includes:
- Low amount of iodine in the diet
- Hashimoto's disease, associated with hypothyroidism
- Genetic defect in the receptors responsible for releasing TSH or thyroid-stimulating hormone
- Radiation treatments that were undergone at an early age such as in child hood to the head or neck area
Various Nodule Types
There are different types of nodules that may develop in the thyroid gland:
Colloid nodule - The type of nodule is noncancerous or benign. It manifests itself as an overgrowth of normal thyroid tissue. It is possible to have one colloid nodule or several. Though it is possible for these nodules to become larger in size, they do not spread to other parts of the body and are contained only in they thyroid gland.
Follicular adenoma - This nodule type is also noncancerous or benign.
Thyroid cyst - These can be benign or malignant depending. These are fluid-filled areas of the thyroid glands that can differ in size. They can measure from less than 1/3 of an inch in diameter to over one 1 inch. Thyroid cysts are usually filled with fluid. Some thyroid cysts have solid components. These are called complex cysts. Fluid-filled cysts are generally benign. Complex cysts can at times be malignant.
Inflammatory nodule - This nodule type may at times develop resulting from chronic inflammation of the thyroid. This condition is called thyroiditis. There is a rare form of thyroiditis called subacute thyroiditis, which is accompanied by severe pain within the thyroid gland. There are other types of thyroiditis that are painless and sometimes happen after pregnancy. This is called postpartum thyroiditis.
Thyroid cancer - There is only a small chance that nodules are cancerous if a physician determines that you have any. If you have a family history of thyroid cancer or any endocrine cancer, you will be at higher risk. Also, if you are a man younger than 30 years of age or older than 60 years of age, with a history of head or neck radiation, you would also be at risk. Cancerous nodules are generally large in size and firm to the touch often causing neck discomfort and/or pain.
Multinodular goiter - "Goiter" refers to any enlargement in the thyroid gland. The appearance of several nodules can lead to a goiter. This is referred to as multinodular goiter. This condition causes tightness in the throat accompanied by difficulty in swallowing and breathing.
Hyperfunctioning thyroid nodule (toxic adenoma, toxic multinodular goiter, Plummer's disease) - TSH is released by the pituitary gland, which regulates the production of thyroid hormones. Hyperfunctioning thyroid nodules that become larger and actually produce thyroid hormones separate from the influence of TSH or thyroid-stimulating hormone. Hyperfunctioning thyroid nodules create a situation where there are high blood levels of thyroxine accompanied by low or even nonexistent levels of TSH. A genetic defect of TSH receptors may be a reason for overactivity of nodules.
The Risk Factors
Thyroid nodules are quite common. In fact, up to 50% of people may have one. The exact cause of thyroid nodules is still unknown although there are some factors that seem to increase the risk of having one. This includes:
Heredity - Family history such as the existence of nodules in parents or in siblings tends to put an individual at a higher risk of developing nodules.
Age - The chances of developing thyroid nodules grow higher as you increase in age. Changes may happen in your thyroid as part of the aging process.
Gender - Statistically, women are more likely to develop thyroid nodules when compared to men.
Exposure to radiation - In the 1940s and 50s, many persons were often treated with radiation for conditions that were noncancerous such as in the case of acne or enlarged tonsils. If you, as a child, experience this type of treatment or experienced any therapy employing the use of radiation to your neck or head for the conditions mentioned above, then you have a higher risk of developing thyroid nodules. You would also be at a higher risk if you were exposed to radioactive particles that became airborne during any atomic weapons testing or if you were exposed to radiation resulting from a nuclear power plant accident.
Specific thyroid conditions - If you've had thyroiditis or a chronic inflammation of the thyroid gland, this would also put you at higher risk.
What Are The Complications?
In general, thyroid nodules are non-cancerous or benign, but at times, they can lead to serious problems. Larger nodules or a number of nodules appearing together can lead to multinodular goiter. This condition can interfere with swallowing or breathing. In can become even more of a serious problem when these nodules or goiter produces thyroid hormone, which can lead to hyperthyroidism.
Along with assorted symptoms such as unexplained weight loss, muscle fatigue, intolerance to heat, and high anxiety, hyperthyroidism can lead to other complications:
Heart-related complications - This type of complication includes a rapid heartbeat, heart rhythm disorder and even congestive heart failure. Congestive heart failure is the condition of the heart being no longer strong enough to circulate blood throughout the body.
Osteoporosis - This is when your bones become weak and brittle due to a lack of calcium. The overall health of bones depends to a certain extent on the amount of calcium and minerals found in them. An excess of thyroid hormone or hyperthyroidism, can disrupt the incorporation of calcium into the bones. In the situation where a patient develops hyperthyroidism, the bones are the first to display the sign or symptoms of the disorder before anything else. This is the case with postmenopausal women who are in the group of individuals with a high risk of developing osteoporosis.
Thyrotoxic crisis - This is the term used to describe the sudden and possibly life threatening intensify of the above signs and symptoms. This requires immediate medical care should this occur.