Thyroid disorders or dysfunctions (also known as thyroid disease) are medical conditions that affect the function of the thyroid gland.
The thyroid gland is the endocrine organ, a butterfly-shaped organ, located at the base of your neck, at the front, wrapped around the trachea (windpipe), just below the Adam’s apple and above the collarbone.
It is part of an intricate network of glands called the endocrine system. The endocrine system is responsible for coordinating many of your body’s activities. The thyroid gland manufactures hormones that regulate your body’s metabolism.
The thyroid uses iodine to produce vital hormones. Thyroxine, also known as T4, is the primary hormone produced by the gland. After delivery via the bloodstream to the body's tissues, a small portion of the T4 released from the gland is converted to triiodothyronine (T3), which is the most active hormone.
The function of the thyroid gland is regulated by a feedback mechanism involving the brain. When thyroid hormone levels are low, the hypothalamus in the brain produces a hormone known as thyrotropin releasing hormone (TRH) that causes the pituitary gland (located at the base of the brain) to release thyroid stimulating hormone (TSH). TSH stimulates the thyroid gland to release more T4.
Since the thyroid gland is controlled by the pituitary gland and hypothalamus, disorders of these tissues can also affect thyroid function and cause thyroid problems.
Kinds of Thyroid Disorders
There are specific kinds of thyroid disorders that includes:
Hypothyroidism (overactive thyroid) is a condition in which the thyroid gland produces an abnormally low amount of thyroid hormone. It can develop from problems within the thyroid gland, pituitary gland, or hypothalamus. Symptoms of hypothyroidism can include:
poor concentration or feeling mentally "foggy"
dry, rough skin
muscle and joint aches
swelling of the legs
prolonged or excessive menstrual bleeding in women
increased cholesterol levels
slow heart rate
On some occasion, there is a state in which people do not have symptoms of hypothyroidism and have a normal amount of thyroid hormone in their blood, this can be referred to Subclinical Hypothyroidism. The only abnormality is an increased TSH on the person’s blood work. This implies that the pituitary gland is working extra hard to maintain a normal circulating thyroid hormone level and that the thyroid gland requires extra stimulation by the pituitary to produce adequate hormones. Most people with subclinical hypothyroidism can expect the disease to progress to obvious hypothyroidism, in which symptoms and signs occur.
Some common causes of hypothyroidism include:
Hashimoto's thyroiditis (an autoimmune condition that causes inflammation of the thyroid gland)
Thyroid hormone resistance
Other types of thyroiditis (inflammation of the thyroid), such as acute thyroiditis and postpartum thyroiditis
Hyperthyroidism describes excessive production of thyroid hormone, a less common condition than hypothyroidism. Symptoms of hypothyroidism usually relate to increased metabolism. In mild cases, there may not be apparent symptoms. Symptoms and signs of hyperthyroidism can include:
fast heart rate
intolerance for heat
increase in bowel movements
unintentional weight loss
Some of the most common causes of hyperthyroidism are:
Toxic multinodular goiter
Thyroid nodules that overexpress thyroid hormone (known as "hot" nodules)
Excessive iodine consumption
Goiter is a noncancerous enlargement of the thyroid gland regardless of cause. The most common cause of goiter worldwide is iodine deficiency in the diet. Researchers estimate that goiter affects 200 million of the 800 million people who are iodine-deficient worldwide.
A goiter is not a specific disease per se. A goiter may be associated with hypothyroidism, hyperthyroidism, or normal thyroid function.
Goiter can affect anyone at any age, especially in areas of the world where foods rich in iodine are in short supply. However, goiters are more common after the age of 40 and in women, who are more likely to have thyroid disorders. Other risk factors include family medical history, certain medication usage, pregnancy, and radiation exposure.
There might not be any symptoms if the goiter isn’t severe. The goiter may cause one or more of the following symptoms if it grows large enough, depending on the size:
swelling or tightness in your neck
difficulties breathing or swallowing
coughing or wheezing
hoarseness of voice
Thyroid nodules are lumps or abnormal masses that form on or in the thyroid gland. Nodules may be single or multiple and can vary in size. About 1 percent of men and 5 percent of women living in iodine-sufficient countries have thyroid nodules that are large enough to feel. About 50 percent of people will have nodules that are too tiny to feel.
The causes aren’t always known but can include iodine deficiency and Hashimoto’s disease. The nodules can be solid or fluid-filled.
Most are benign, but they can also be cancerous in a small percentage of cases. As with other thyroid-related problems, nodules are more common in women than men, and the risk in both sexes increases with age.
Most thyroid nodules don’t cause any symptoms. However, if they grow large enough, they can cause swelling in your neck and lead to breathing and swallowing difficulties, pain, and goiter.
Some nodules produce thyroid hormone, causing abnormally high levels in the bloodstream. When this happens, symptoms are similar to those of hyperthyroidism and can include:
high pulse rate
On the other hand, symptoms will be similar to hypothyroidism if the nodules are associated with Hashimoto’s disease. This includes:
Thyroid cancer is far more common among adult women than men or youth. About 2/3 of cases occur in people under age 55. There are different kinds of thyroid cancer, depending upon the specific cell type within the thyroid that has become cancerous. Most cases of thyroid cancer have a good prognosis and high survival rates, especially when diagnosed in its early stages.
Symptoms of thyroid cancer can include:
a lump in the neck
tight feeling in the neck
trouble breathing or swallowing
Diagnosing Thyroid Disorders
In addition to thorough medical history and physical exam, specialized tests are used to diagnose thyroid disorders.
Thyroid disease can be difficult to diagnose because symptoms are easily confused with other conditions. Fortunately, there is a test, called the thyroid stimulating hormone (TSH) test that can identify thyroid disorders even before the onset of symptoms.
But sometimes, especially if one has a nodule in the thyroid gland, the doctor may order other tests such as an ultrasound study or a special scan, called a thyroid scan, that's like an X-ray.
When thyroid disease is caught early, treatment can control the disorder even before the onset of symptoms.
Treatment for Thyroid Disorders
The goal of treatment for any thyroid disorder is to restore normal blood levels of thyroid hormone.
Hypothyroidism is treated with a drug called levothyroxine. This is a synthetic hormone tablet that replaces missing thyroid hormone in the body. With careful monitoring, your doctor will adjust your dosage accordingly, and you'll soon be able to return to your normal lifestyle.
Hyperthyroidism, generally more difficult to treat, requires the normalization of thyroid hormone production. Treatment could involve drug therapy to block hormone production, radioactive iodine treatment that disables the thyroid, or even thyroid surgery to remove part or the entire gland.
The most popular treatment is radioactive iodine. This therapy often results in hypothyroidism, requiring the use of levothyroxine (synthetic replacement hormone) in order to restore normality.
What is the Prognosis for Thyroid Disorders?
In most cases, thyroid disorders can be well managed with medical treatment and are not life threatening. Some conditions may require surgery. The outlook for most people with thyroid cancer is also good, although patients with thyroid cancer that has spread throughout the body have a poorer prognosis.
Preventing Thyroid Disorders
In most cases, you can’t prevent hypothyroidism or hyperthyroidism. In developing countries, hypothyroidism is often caused by iodine deficiency. However, this deficiency is rare in regions where there is the addition of iodine to table salt.
Hyperthyroidism is often caused by Graves’ disease, an autoimmune disease that isn’t preventable. You can set off an overactive thyroid by taking too much thyroid hormone. If you’re prescribed thyroid hormone, make sure to take the correct dose. In rare cases, your thyroid can become overactive if you eat too many foods that contain iodine, such as table salt, fish, and seaweed.
Though you may not be able to prevent thyroid disease, you can prevent its complications by getting diagnosed right away and following the treatment your doctor prescribes.