The thyroid is a small, butterfly-shaped gland located at the base of the neck below the Adam's apple. It is part of a complex network of glands called the endocrine system, which is responsible for coordinating many of the body's activities.
The thyroid gland manufactures hormones that regulate the body's metabolism (the process of creating and using energy). When the thyroid produces too much (hyperthyroidism) or not enough (hypothyroidism) hormone, several problems can occur.
Also known as chronic lymphatic thyroiditis, Hashimoto's disease is the most common cause of hypothyroidism (underactive thyroid) in the United States. It can occur at any age but is most common in middle-age women. The disease occurs when the body's immune system attacks and slowly destroys the thyroid gland and its capacity to produce hormone.
Symptoms of Hashimoto's Disease
Mild cases of Hashimoto's disease sometimes present no recognizable symptoms, and the disease can remain stable for years. Symptoms are often subtle, and they are not specific, which means they mimic symptoms of many other conditions, and include:
- mild weight gain
- dry skin and/or hair
- heavy and irregular menstruation
- intolerance to cold
- enlarged thyroid (goiter)
Tests and Diagnosis for Hashimoto's Disease
Testing the level of thyroid-stimulating hormone (TSH) is often the initial step when screening for any type of thyroid disorder. If a patient is showing several of the above symptoms, a doctor might order a blood test to check for increased levels of TSH and also low levels of thyroid hormone (T3 or T4). Because Hashimoto's disease is an autoimmune disorder, the blood test would also reveal the presence of abnormal antibodies that might be attacking the thyroid.
Treatment and Prognosis of Hashimoto's Disease
There is no known cure for Hashimoto's disease. However, hormone-replacing medication is often used to raise thyroid hormone levels (or lower TSH levels) and, thus, minimize the symptoms of the disease. In rare advanced cases of goiter (an enlarged thyroid), surgery might be necessary to remove part or all of the thyroid gland. Because the disease progresses slowly, it is usually detected at an early stage, remains stable for years, and is easily treated with hormone replacement therapy.
Named for the physician who first described it more than 150 years ago, Graves' disease is the most common cause of hyperthyroidism (overactive thyroid). It is an autoimmune disorder and occurs when the body's immune system mistakenly attacks the thyroid gland, causing it to overproduce the hormone responsible for regulating metabolism. The disease is hereditary and may develop at any age in men or women, but it is more common in women over the age of 20. Other risk factors include stress, pregnancy, and smoking.
Symptoms of Graves' Disease
With a high level of thyroid hormone in the bloodstream, the body's systems speed up and cause symptoms that are common to hyperthyroidism. Symptoms are not specific, which means they are common to other conditions, and can include:
- increased or irregular heartbeat
- excessive sweating
- difficulty sleeping
- diarrhea or frequent bowel movements
- altered menstrual cycle
- enlarged thyroid (goiter)
- Graves' ophthalmopathy
- bulging eyes
- reddening or inflamed eyes
- excessive tearing
- swelling eyelids
- light sensitivity
- ulcers, double vision, blurred vision (less common)
- Graves' dermopathy(less common)
- reddening and swelling of the skin
Tests and Diagnosis for Graves' Disease
A simple physical exam can reveal an enlarged thyroid, irritated or bulging eyes, and signs of increased metabolism, including rapid pulse and high blood pressure. The doctor will also call for blood tests to check for high levels of thyroxine (T4) and low levels of thyroid-stimulating hormone (TSH), both of which are signs of Graves' disease. A radioactive iodine uptake might also be administered to measure how quickly the thyroid takes up iodine, which it needs to function properly. A high uptake of iodine is a sign of Graves' disease.
Treatment of Graves' Disease
There is no treatment to stop the immune system from attacking the thyroid gland and causing it to overproduce hormone. However, the symptoms of Graves' disease can be controlled in several ways, often with a combination of treatments. Beta blockers are medications used for rapid heart rate, anxiety, and sweating. Anti-thyroid medications are prescribed to prevent the thyroid from producing excessive amounts of hormone. And radioactive iodine is often administered to destroy all or part of the thyroid and render it incapable of overproducing thyroid hormone. Surgery to remove the thyroid gland is an option for patients who cannot tolerate anti-thyroid drugs or radioactive iodine. In most cases, successful hyperthyroidism treatment results in hypothyroidism, and patients must take hormone-replacement medication from that point forward.
Prognosis of Graves' Disease
If left untreated, Graves' disease can lead to heart problems, brittle bones, and, in rare cases, a condition called thyrotoxic crisis, which is an intensification of hyperthyroidism symptoms. But early detection is routine, and because Graves' disease responds well to treatment, the outlook for patients is usually positive. If treated with surgery, there is a very slight risk of damage to the vocal cords because of their proximity to the thyroid. In most cases after the initial treatment, patients can expect to be on a lifetime regimen of hormone-replacement medication, especially if all or part of the thyroid is removed during surgery.
Goiter is a noncancerous enlargement of the thyroid gland. The most common cause of goiter worldwide is iodine deficiency in the diet. In the U.S., where iodized salt provides plenty of iodine, goiter is often caused by (and a symptom of) hyperthyroidism (overactive thyroid). 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 50 and in women, who are more likely to have thyroid disorders. Other risk factors include family medical history, certain medications, pregnancy, and radiation exposure.
Symptoms of Goiter
If the goiter is not severe, there might not be any symptoms. If the thyroid grows large enough, depending on the size, it may cause one or more of the following symptoms:
- swelling/tightness in the neck
- breathing and/or swallowing difficulties
- coughing or wheezing
Tests and Diagnosis for Goiter
During a routine physical exam, a doctor will feel the neck area and have the patient swallow. Blood tests will reveal the levels of thyroid hormone, thyroid-stimulating hormone, and antibodies in the bloodstream, which will diagnose thyroid disorders that are often a cause of goiter. An ultrasound of the thyroid can check for swelling or nodules.
Treatment of Goiter
Goiter is usually treated only when it becomes severe enough to cause symptoms. If goiter is the result of iodine deficiency, then small doses of iodine can be administered. Radioactive iodine can be used to shrink the thyroid gland. Surgery will remove all or part of the gland. Because goiter is often a symptom of hyperthyroidism, the treatments usually overlap.
Prognosis for Goiter
Goiters are often associated with highly treatable thyroid disorders, such as Graves' disease and are not usually a cause for concern. Goiters themselves are benign. Because there is no pain associated with them, small goiters often go undetected and are not usually treated even if they are diagnosed. Sometimes goiters go away on their own. Sometimes they grow larger and, if left untreated, can present serious complications, such as difficulty breathing and swallowing.
Thyroid nodules are growths that form on or in the thyroid gland. The causes are not 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.
Symptoms of Thyroid Nodules
Most thyroid nodules do not cause any symptoms. However, if they grow large enough, they can cause swelling in the 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
- increased appetite
- weight loss
- clammy skin
On the other hand, if the nodules are associated with Hashimoto's disease, symptoms will be similar to those associated with hypothyroidism and can include:
- weigh gain
- hair loss
- dry skin
- cold intolerance
Tests and Diagnosis of Thyroid Nodules
Most nodules are detected during a normal physical exam. They can also be detected during an ultrasound, CT scan, or an MRI that is being done for unrelated head or neck conditions. Once a nodule is detected, other procedures—TSH test and a thyroid scan—can check for hyperthyroidism or hypothyroidism. A fine-needle aspiration (FNA) biopsy is used to take a sample of cells from the nodule and determine whether the nodule is cancerous.
Treatment and Prognosis of Thyroid Nodules
Benign thyroid nodules are not life-threatening and usually don't require treatment. For larger noncancerous nodules that do need treatment, the outlook is excellent. If the biopsy reveals a benign nodule that is small in size, the treatment is often a "wait and see" approach that involves close monitoring with regular checkups. If the nodule does not change over time, nothing is usually done to remove it. If the nodule grows, another biopsy might be performed and treatment options might include radioactive iodine to shrink the nodules and hormone suppression to limit the amount of TSH and hormone tissue (hormone suppression's effectiveness is a matter of heated debate).
Cancerous nodules are pretty rare—estimated to be between 4-5 percent of diagnosed thyroid nodules. According to the National Cancer Institute, there are about 37,000 new cases of thyroid cancer diagnosed in the U.S. each year (compared to 219,000 new cases of lung cancer, for example). Treatment varies depending on the type of tumor. Removing the thyroid through surgery is usually the treatment of choice. Radiation therapy is sometimes used with or without surgery. If the cancer spreads to other parts of the body, chemotherapy is usually required.