- Goitre is enlargement of the thyroid gland, which is situated in the neck and plays a vital role in regulating metabolism.
- Dietary iodine deficiency, hyperthyroidism and hypothyroidism are some of the causes of goitre.
- Goitre due to iodine deficiency is now rare in developed countries, but still common in several developing regions.
- In addition to swelling in the neck region, symptoms of goitre may include difficulty breathing or swallowing.
- Many small to moderate-sized goitres are treated with thyroid hormone replacement medication; larger goitres may require surgery.
Goitre is an enlargement of the thyroid gland, which is located in the front of the neck directly below the voicebox. The function of this gland is to regulate the body's metabolism: it does this by producing thyroid hormone, which increases cellular activity in most bodily tissues. With goitre, the enlargement of the thyroid gland is big enough to be visible on ultrasounds or x- rays, and, if it becomes very large, can be seen as a mass in the neck area.
A goitre can be the result of several types of growth in the thyroid gland. The goitre may be a temporary problem and will resolve spontaneously, or a symptom of a more serious thyroid condition that requires medical treatment.
A simple, or nontoxic, goitre involves an enlargement of the thyroid gland that is not associated with overproduction of thyroid hormone, inflammation or malignancy (cancerous growth).
A toxic goitre is one involving excessive production of thyroid hormone.
Thyroid enlargement can be uniform (diffuse goitre) or the gland may be enlarged due to one or more nodules (nodular goitre). Nodules are small lumps within an otherwise normal thyroid gland.
There are many causes of thyroid enlargement, and sometimes the cause of goitre cannot be determined.
Two of the causes of simple goitre are as follows:
- Iodine deficiency. A dietary deficiency of iodine, which is a key ingredient in the manufacture of thyroid hormone, can cause goitre in certain populations. Such a goitre is termed endemic, meaning a high incidence of goitre (in more than 10 percent of the population) occurs in a specific community or geographic area. Inadequate dietary intake of iodine, and thus endemic goitre, typically occurs more commonly in fresh water and lake areas than on the sea coast, because of the lack of iodine in fresh water.
- Ingesting large quantities of goitrogenic foods or drugs, which contain substances that decrease thyroid hormone production. Examples of goitrogenic foods include rutabagas (swedes), cabbage, soya, peanuts, peaches, strawberries, spinach and radishes. Goitrogenic drugs include lithium, cobalt, phenylbutazone (in some anti-inflammatory medications) and iodides (excessive iodine intake can also cause goitre). This cause of goitre is usually termed sporadic i.e. goitre arises in nonendemic areas as a result of a stimulus that does not affect the population generally. However, sometimes dietary or waterborne goitrogens may act together with iodine deficiency to produce goitre in a population.
When the thyroid gland is unable to meet the metabolic demands of the body through sufficient hormone production, as with cases of endemic or sporadic goitre, it compensates by enlarging. This usually overcomes mild impairment of hormone synthesis, and maintains normal metabolism. When the underlying complication is severe, however, compensatory responses may be inadequate to overcome the impairment, and the person will develop both a goitre and hypothyroidism (underactive thyroid).
Other causes of goitre include:
- Hyperthyroidism: the thyroid gland is overactive, and secretes excessive thyroid hormone. The most common cause of hyperthyroidism is Graves' disease, an autoimmune condition in which the body's immune system mistakenly attacks the thyroid gland and stimulates it to produce excess thyroid hormone. The overstimulation of the thyroid gland results in swelling.
- Hypothyroidism: underactive thyroid gland. Hashimoto's disease, or lymphocytic thyroiditis, is the most common cause of an underactive thyroid gland. In Hashimoto's disease, also an autoimmune disease, abnormal antibodies (proteins that attack invasive substances as part of the body's immune system) impair the thyroid gland's ability to produce hormones. The pituitary gland in the brain then releases thyroid-stimulating hormone (TSH) in an attempt to stimulate the thyroid gland to produce thyroid hormone. The additional TSH may cause the thyroid gland to enlarge.
- Nodules may form in the thyroid gland. The cause is unknown, but people exposed to certain types of radiation seem more likely to develop this condition. Over 90 percent of nodules are noncancerous and do not lead to cancer.
- Thyroid cancer. Cancerous growth can cause enlargement of the thyroid gland. It may be difficult to distinguish early stage thyroid cancer from a noncancerous nodule.
- Inflammation. Thyroiditis, an inflammatory condition of the thyroid gland, can cause enlargement. This condition may be painful, especially when swallowing.
- An enlarged thyroid can be present at birth for a number of different reasons.
- Pregnancy. A hormone produced during pregnancy, human chorionic gonadotropin (HCG), may cause slight enlargement of the thyroid gland. Sometimes, excess HCG is produced, leading to greater swelling.
Who gets it and who is at risk?
The following factors increase your risk for developing goitre:
- Female gender
- Being over 40 years old
- An inadequate dietary intake of iodine
- Residence in an area endemic for goitre
- Ingestion of large amounts of goitrogenic foods or drugs
- Having a family history of goiter
Before the early 20th century, the most common cause of goitre was a shortage of dietary iodine in areas where the soil or water was deficient in this element. The incidence of iodine deficiency is now low in developed countries because of the use of iodised salt and widespread distribution of foods from iodine sufficient areas. In addition, iodine often occurs naturally in some foods such as dairy products and seafood, or may enter foods inadvertently during processing. The result is that only about 10-20% of the population in developed countries still suffers from goitre. In several developing countries, however, particularly parts of Asia and Africa, goitres due to iodine deficiency are still common. In developed countries, goitre is more commonly caused by autoimmune thyroid problems that produce an inflammatory reaction in the thyroid gland.
Symptoms and signs
Symptoms and signs of goitre may include:
- Thyroid enlargement varying from a single small nodule to widespread swelling at the base of the neck
- A feeling of fullness or tightness in your neck or throat. Some goitres are tender to the touch.
- Difficulty breathing, including feeling short of breath, wheezing or coughing from compression or displacement of the windpipe, especially at night.
- Difficulty swallowing from compression of the throat. You may have a feeling that food is getting stuck in your throat.
- Hoarseness, or a slight change in voice (as a result of nerve compression in the neck).
- Neck vein distention, dizziness, and getting red in the face when you raise your arms above your head (as a result of blood vessel compression in the neck).
- If you have hyperthyroidism, you may also experience increased heart rate, raised blood pressure, nervousness, diarrhoea, muscle weakness, hand tremors, and weight loss despite increased appetite.
- If you have hypothyroidism, you may also experience lethargy, slowed physical and mental functions, hair loss, dry skin, decreased heart rate, intolerance to cold, constipation, easy weight gain, depression, and tingling or numbness in your hands.
- Acute, painful swelling in the neck may indicate sudden hemorrhage (bleeding) into a thyroid nodule.
Your doctor will examine your neck in order to determine the degree of gland enlargement and areas of tenderness. In some cases, your doctor may be able to feel the presence of nodules. Your doctor will also do a general physical examination and ask you about any other symptoms you may be experiencing.
Diagnosis may also involve the following signs and tests:
- Hormone testing. Blood tests can determine the amount of hormone produced by your thyroid and pituitary glands. Important components of blood testing include T4, T3, TSH and thyroid antibodies. With hypothyroidism, for example, the level of thyroid hormone will be low and the level of thyroid-stimulating hormone will be elevated.
- Antibody test. Some causes of goitre involve production of abnormal antibodies. A blood test may confirm the presence of these.
- Ultrasound. Sound waves are transmitted through your neck and form images of internal structures on a computer screen. The images help to show the size of your thyroid gland and whether it contains nodules that may not have been evident during physical examination.
- Thyroid scan (radioactive iodine uptake): With this type of scan, you ingest a small amount of radioactive iodine, which is then absorbed by your thyroid gland. A scan is performed to reveal an image of the distribution of the radioactive material in your thyroid gland, and to show if the swelling is localised or diffuse. Radioactive iodine uptake is also used to indicate whether thyroid nodules are cancerous and require further evaluation.
Treatment of goitre depends on the size of the enlargement and the underlying cause. Your doctor may recommend:
- Observation. If your goitre is small and not causing problems, your doctor may suggest a wait-and-see approach before taking further steps. Some goitres may not require treatment.
- Medication. Most small to moderate-sized goitres are typically treated with thyroid hormone replacement medication, taken orally. Hormone replacement inhibits the release of thyroid stimulating hormone from your pituitary gland and allows for stabilisation of the thyroid gland. The synthetic thyroid hormone levothyroxine (Levothroid, Levoxyl, Synthroid) is the drug usually used for thyroid hormone replacement. Hormone replacement can retard or stop growth of the goitre, but will not typically shrink it.
In certain cases of thyroiditis, aspirin or a corticosteroid medication may be recommended to reduce inflammation.
Small doses of iodine may be prescribed to treat iodine deficiency.
- Surgery. Removing all (thyroidectomy) or part (subtotal thyroidectomy) of your thyroid gland may be recommended if you have a large goitre that is uncomfortable, cosmetically unsightly, restricts breathing or swallowing or is compressing blood vessels in the neck, is unresponsive to medication, or if you have thyroid cancer. Suspicion of malignancy in an enlarged thyroid gland may also be an indication for thyroidectomy. However, in most cases, surgical removal of a goitre for fear of cancer is not recommended.
You may need to take levothyroxine after surgery depending on the amount of thyroid removed.
- Radioactive iodine. In some cases, radioactive iodine is used to treat an overactive thyroid gland. The iodine is taken orally and travels via the bloodstream to the thyroid gland, where it destroys thyroid cells. The treatment shrinks the goitre but may result in an underactive thyroid gland. Life-long thyroid hormone replacement then becomes necessary.
- Eliminating or reducing goitrogenic foods or drugs may be indicated for sporadic goitre.
The outcome of goitre depends on its underlying cause. With treatment, the expected outcome for most cases of goitre is good. Some simple goitres may even resolve spontaneously.
Complications of goitre may include:
- A simple goitre may progress to a toxic nodular goitre.
- Where iodine deficiency is severe, goitre may be associated with varying degrees of hypothyroidism. Cretinism (arrested development due to congenital hypothyroidism) occurs with increased frequency in children of parents with endemic goitre.
- Occasionally, when a person with a nodular goitre receives excess iodine therapy, hyperthyroidism or thyrotoxicosis (a toxic condition due to hyperactivity of the thyroid gland) may develop.
- Sometimes goitres will grow into the chest where they can cause additional problems. This extension may compress large blood vessels.
- Progressive thyroid enlargement and/or the development of hardened nodules may indicate thyroid cancer. Thyroid cancer is a fairly common malignancy; however, the vast majority of cases have excellent long-term survival.
- Haemorrhage into a cyst.
- Compression of the food pipe, trachea and nerves.
- Cosmetic problems.
Endemic goitre can be prevented by using iodised table salt or water, and limiting goitrogenic foods and drugs prevents sporadic goitre.
When to call the doctor
Call your doctor if you experience any swelling in the front of your neck, or any of the symptoms of hypothyroidism or hyperthyroidism. Your doctor can determine whether your thyroid is causing your neck to be swollen and what the cause might be.
Reviewed by Prof. Don du Toit, Faculty of Health Sciences, University of Stellenbosch