Overview of the thyroid gland
The thyroid is a butterfly-shaped gland found in the lower neck, just beneath the Adam’s apple. The hormones it releases control the body’s growth and metabolism. They affect processes like heart rate, digestion and temperature.
When the levels of thyroid hormone are too high, symptoms of hyperthyroidism (overactive thyroid) may present, such as increased heart rate, weight loss and anxiety. Conversely, when the levels are abnormally low, there may be symptoms of hypothyroidism (underactive thyroid), like fatigue, weight gain and depression.
What is thyroiditis?
Thyroiditis is a term for inflammation of the thyroid gland, a condition which causes the levels of thyroid hormone in the body to go beyond the normal range.
Thyroiditis can be caused by several clinical disorders that present in different ways and require different courses of treatment, ranging from medication to surgery. The most common disorders include Hashimoto’s thyroiditis, postpartum thyroiditis and De Quervain’s thyroiditis.
It is estimated that women are roughly five to eight times more likely than men to experience thyroid problems, with around one in eight women developing a thyroid disorder at some point in their lifetime. Thyroiditis can be a serious condition, and requires management by a medical practitioner.
Symptoms of thyroiditis
The symptoms of thyroiditis depend on whether the levels of thyroid hormone in the blood are too high (hyperthyroidism or thyrotoxicosis) or too low (hypothyroidism).
Symptoms of hyperthyroidism (thyrotoxicosis) include:
- Anxiety or nervousness
- Increased sweating
- Heat intolerance
- Weight loss or difficulty gaining weight, despite a good appetite
- Insomnia (sleeplessness)
- Racing heart or palpitations (pronounced awareness of one’s heartbeat)
- High blood pressure
- Increased frequency of bowel movements
- Nausea and vomiting
- Fatigue (generally feeling tired or weak)
- Tremors (shaky hands)
- Feeling of weakness in the muscles (particularly in the upper arms and thighs)
- Difficulty exercising
- Eye bulging and irritation
- Light or no menstruation
Symptoms of hypothyroidism include:
- Fatigue (generally feeling tired or weak)
- Sensitivity to cold
- Dry skin
- Poor exercise tolerance
- Unexplained weight gain
- Brittle nails
- Hair loss
- Tongue enlargement (swelling)
People affected by thyroiditis may present with a goiter – otherwise known as an enlarged thyroid gland. There may be noticeable swelling in the lower part of the neck. Goiters can be caused by hyper or hypothyroidism, as well as thyroid nodules and a number of other conditions that affect the thyroid.
Thyroid goiters are usually painless, but can cause a tight feeling in the throat, hoarseness, coughing, and difficulty swallowing and breathing (if they are very large). A goiter does not necessarily indicate that thyroid function has been compromised, and small thyroid goiters may not require medical treatment.
Types of thyroiditis
There are a number of different types of thyroiditis. Many of these conditions seem to run in families, and they tend to affect a higher number of women than men.
Hashimoto’s thyroiditis (Hashimoto’s disease)
Also known as chronic lymphocytic thyroiditis, this is the most common type of thyroiditis. It is an autoimmune condition in which the immune system mistakenly attacks the thyroid gland, causing gradual damage that can lead to hypothyroidism over time. Hashimoto’s thyroiditis is more prevalent among women than men, and is commonly associated with a family history of thyroid disorders.
Hashimoto’s thyroiditis tends to progress slowly and can take months or even years to be detected. Those affected may present with a painless goiter, symptoms of hypothyroidism and high levels of thyroid antibodies. Though less common, there may also be symptoms of hyperthyroidism. The hypothyroidism, which is often lifelong, is treated with thyroid hormone replacement.
Hashimoto’s thyroiditis is sometimes associated with other autoimmune conditions, including Addison’s disease, type 1 diabetes, pernicious anemia, celiac disease and connective tissue disorders like rheumatoid arthritis. For more information, see the dedicated page on Hashimoto’s thyroiditis.
Also known as Ord’s disease, this autoimmune condition is characterized by atrophy of the thyroid gland and hypothyroidism. It is very similar to Hashimoto’s disease, apart from the shrinking of the thyroid gland (instead of the development of a goiter). Ord’s disease and Hashimoto’s disease have historically been classified as separate disorders, but research suggests that they may instead be different manifestations of autoimmune thyroiditis, with some medical practitioners calling for the combined term Ord-Hashimoto’s disease to be used.
De Quervain’s thyroiditis (subacute thyroiditis)
Also known as painful subacute thyroiditis, subacute nonsuppurative thyroiditis, giant cell thyroiditis and subacute granulomatous thyroiditis, this is a relatively rare condition that mostly affects middle-aged women who have recently had a viral infection of the upper respiratory tract. Overall, De Quervain’s thyroiditis is the most common cause of a painful thyroid gland.
The main symptoms of De Quervain’s thyroiditis are fever, pain in the thyroid region of the neck (which may radiate to the jaw and ears) and an enlarged thyroid. Initially, a person with De Quervain’s may present with symptoms of hyperthyroidism, as the condition causes the release of high levels of thyroid hormone. This is sometimes followed by a temporary (transient) phase of hypothyroidism.
De Quervain’s thyroiditis is usually self-limiting, with the condition clearing on its own within a few months. Treatment is aimed at minimizing pain and discomfort, and aspirin or another NSAID (Nonsteroidal Anti-Inflammatory Drug), such as ibuprofen may be recommended. In severe cases, a corticosteroid may be prescribed as a potent anti-inflammatory measure. A beta-blocker may be given to ease some of the symptoms of hyperthyroidism, like a racing heart, high blood pressure, feeling agitated or having tremors. The temporary hypothyroidism that is often the last stage of the condition, before patients recover, may necessitate short-term treatment with thyroid hormone replacement.
Thyroid function generally returns to normal (a euthyroid state), though in a few cases De Quervain’s can recur and result in permanent hypothyroidism.
Also known as painless thyroiditis or subacute lymphocytic thyroiditis, this is an autoimmune condition (autoimmune meaning that the immune system attacks healthy cells) that presents with an initial period of hyperthyroidism (three months or less), followed by temporary hypothyroidism. Silent thyroiditis generally resolves on its own within 12-18 months, though in some cases the hypothyroidism may occasionally be permanent. Treatment may include beta-blockers to relieve the symptoms of hyperthyroidism and thyroid hormone replacement, when necessary, in the hypothyroid phase.
Sometimes classified as a type of silent thyroiditis, postpartum thyroiditis affects people who have recently (within the last 12 months) given birth, or had a miscarriage or medical abortion. The condition is autoimmune in nature and typically manifests with an initial period of hyperthyroidism, followed by hypothyroidism that may be temporary or permanent. Not all people experience both phases. Postpartum thyroiditis most often affects people with a prior history of thyroid dysfunction, and resembles Hashimoto’s thyroiditis – as does regular silent thyroiditis.
Some medications may cause hypothyroidism or, more rarely, hyperthyroidism. Treatment with lithium is known to cause hypothyroidism in 5-15 percent of people and goiter in up to 37 percent. Iodine and iodine-containing medications, such as amiodarone or interferon, can also affect thyroid function. Drugs used to treat hyperthyroidism can result in a hypothyroid state, and vice versa, if dosages are incorrect. Treatment requires management of medications and dosages with a medical practitioner.
A number of people who undergo radioactive iodine therapy for hyperthyroidism, develop radiation-induced thyroiditis after the procedure. Radiation therapy for certain cancers, such as lymphoma, head and neck cancers, can also trigger thyroiditis. Those affected may present with symptoms of hyper or hypothyroidism, as well as tenderness in the thyroid area. Treatment may involve beta-blockers to alleviate symptoms of temporary (transient) hyperthyroidism, painkillers and thyroid hormone replacement where necessary.
Acute infectious thyroiditis
This rare type of thyroiditis, also known as suppurative thyroiditis or acute thyroiditis (to be distinguished from subacute thyroiditis), is caused by an infection of the thyroid gland with bacteria or other microbes. The condition is associated with a weakened immune system that may be caused by any number of reasons or, in the case of children, an abnormality in the development of the thyroid gland. Most people affected by acute infectious thyroiditis have a pre-existing thyroid disorder such as Hashimoto's thyroiditis or thyroid cancer.
Symptoms include pain in the front of the neck, soreness in the throat, fever and a rapid heart rate. Thyroid hormone levels tend to be within the normal range. The cause of infection is typically determined using fine-needle aspiration (a type of biopsy), after which a treatment option will be prescribed. Most likely, this will require antibiotics or other antimicrobial agents and, in the case of an abscess, surgical drainage. Without effective and timely treatment, the condition can potentially be life-threatening.
Sometimes also called Riedel’s struma or invasive fibrous thyroiditis, this is a very rare type of thyroiditis. The cause is unclear, though it is thought to be either an autoimmune or primary fibrotic (referring to an excessive build-up of connective tissue) disorder. Riedel’s thyroiditis typically presents with a hard, painless mass in the front of the neck. As the disease progresses, affected people may experience hoarseness, difficulty swallowing and breathing, as well as choking. There may also be hypothyroidism and hypoparathyroidism. Treatment may involve corticosteroids, thyroid hormone replacement and surgery.
Diagnosis of thyroiditis (thyroid tests)
A number of diagnostic methods may be used to confirm that thyroiditis or another thyroid condition is present.
Thyroiditis is typically diagnosed with a thyroid function test. This is a blood test that looks at levels of the following:
- TSH (thyroid stimulating hormone)
- FT4 (free thyroxine)
- FT3 (free triiodothyronine) – only occasionally
The amount of thyroxine (the thyroid’s main hormone) secreted by the thyroid gland is regulated by the pituitary gland (also called the hypophysis, a small hormone gland located at the base of the brain). The pituitary gland secretes TSH according to the amount of T4 (thyroxine) that is needed. T4 is converted into T3 (triiodothyronine), which is the biologically active form of thyroid hormone.
If the level of TSH is high and the FT4 low in a blood test, it indicates hypothyroidism. Conversely, if the level of TSH is low and the FT4 high, hyperthyroidism is indicated. The ranges used vary slightly by country and laboratory.
Where the TSH level is slightly elevated, but the FT4 level is normal, subclinical or mild hypothyroidism is indicated. Because this may progress to full-blown hypothyroidism, follow-up tests may be recommended.
When autoimmune thyroiditis is suspected, a medical practitioner may order further blood tests to see whether thyroid antibodies are present at levels above the reference range. These include thyroid peroxidase antibodies (TPOAb) and thyroglobulin antibodies (TgAb) to confirm Hashimoto’s thyroiditis, and thyroid stimulating hormone receptor antibodies (TSHR Ab), which are also called TSH receptor antibodies (TRAbs), in the case of Graves’ disease.
Radioactive iodine uptake test
In some cases (particularly when hyperthyroidism is present), a radioactive iodine uptake test may be recommended – often together with a thyroid scan (a specialized imaging procedure). In both of these tests, a small amount of a weak radioactive substance is administered. A radioactive iodine uptake test allows the medical practitioner to determine whether the thyroid gland, which naturally takes up iodine, is functioning normally, and why thyroid hormone levels may be out of range. A scan can detect thyroid nodules and inflammation.
This non-invasive test may be ordered to check the thyroid for swelling and nodules. It is also used to check the functioning of the parathyroid glands (four glands that are situated on the back of the thyroid and produce parathyroid hormone, which affects the body’s calcium metabolism).
Fine needle aspiration
If a suspicious thyroid nodule is detected, a fine needle aspiration biopsy may be performed to determine whether it is benign (non-cancerous) or malignant (cancerous).
Treatment depends on the type of thyroiditis, as well as its progression. Pain and inflammation caused by thyroiditis may be treated with aspirin, ibuprofen or other anti-inflammatory painkillers (NSAIDs), with the addition of corticosteroids where necessary.
An underactive thyroid is treated with thyroid hormone replacement. This usually takes the form of levothyroxine (a synthetic/lab-created form of T4), with the dosage determined by the severity of the hypothyroidism, as well as the weight and age of the affected person. Regular thyroid blood tests are necessary to ensure that the levels of thyroid hormone do not become too high (thyrotoxicosis) or remain too low.
An overactive thyroid can be treated in a number of ways. There is no single preferred method – the chosen option usually depends on the type and severity of hyperthyroidism, as well as the age and general health of the affected person.
Treatment methods include antithyroid drugs like methimazole, which block the ability of the thyroid gland to produce thyroid hormone, radioactive iodine, which destroys the thyroid cells that produce thyroid hormone and thyroid surgery (thyroidectomy), where most of the thyroid gland is removed, and the resultant hypothyroidism is treated with levothyroxine. Beta-blockers may be prescribed to lessen the symptoms of hyperthyroidism while treatments are taking effect.
Because treatment will depend on the type of thyroiditis experienced, consultation with a medical professional is very important. Taking over-the-counter medication without advice from a healthcare provider is not recommended.
Other thyroid conditions
Also known as diffuse toxic goiter and Basedow’s disease, Graves’ disease is an autoimmune condition in which the thyroid gland is stimulated to produce too much thyroid hormone, causing hyperthyroidism or thyrotoxicosis. Like Hashimoto’s disease, it seems to have a genetic component and is more prevalent among women than men. Graves’ disease is one of the most common causes of hyperthyroidism.
People affected by Graves’ disease may present with painless enlargement of the thyroid gland, symptoms of hyperthyroidism and high levels of thyroid antibodies. In addition, there may be symptoms of Graves’ ophthalmopathy, where the eyes are affected by a gritty sensation, pain or pressure. There may also be swollen eyelids, light sensitivity, double vision or bulging eyes, among other symptoms. Graves’ ophthalmopathy is seen in approximately 30 percent of people affected by Graves’ disease. There may also be reddening and thickening of the skin, most often on the shins or tops of the feet. This is called Graves’ dermopathy or pretibial myxedema, and is rare.
The hyperthyroidism is treated with antithyroid medication, radioactive iodine or thyroid surgery. Where permanent hypothyroidism results, levothyroxine is prescribed to replace the thyroid hormone and is typically taken for life.
Thyroid nodules are lumps in the thyroid gland. They may be solid or filled with fluid. Nodules may be too small to detect without a physical examination, thyroid ultrasound or thyroid scan, or large enough that they are visible and, in rare cases, even obstruct breathing or swallowing.
The majority of thyroid nodules do not cause any symptoms. However, some produce extra thyroxine, which can cause symptoms of hyperthyroidism as thyroid hormone levels go out of range.
Thyroid nodules may be caused by iodine deficiency (rare in the United States, more common in many regions of Europe), overgrowth of normal thyroid tissue (thyroid adenomas) or Hashimoto’s disease, among other conditions.
A thyroid nodule may also be a sign of thyroid cancer. However, most thyroid nodules are benign (non-cancerous growths). It is estimated that only two to three out of 20 thyroid nodules are cancerous.
If a thyroid nodule is non-cancerous (benign) and not causing any symptoms, treatment may not be necessary. Medical practitioners may simply opt to perform regular examinations and thyroid function tests to monitor its progress. Large nodules, and those that cause symptoms, may be removed surgically or treated with radioactive iodine (if they are producing thyroxine).
Thyroid cancer is relatively rare, but rates seem to be increasing. It is thought that this is due to advances in technology which allow medical practitioners to detect small thyroid cancers that may previously have gone unnoticed. Most cases of thyroid cancer are treatable and can be cured, allowing those affected to live a normal life.
Early symptoms of thyroid cancer are rarely noticeable. However, in some cases, firm, painless nodules may be noted. Later symptoms may include rapid growth of a goiter, throat hoarseness or pain that does not go away, difficulty swallowing or breathing, pain in the front of the neck and an unexplained cough.
There are four main types of thyroid cancer:
- Papillary (the most common type)
- Follicular (the second most common type)
- Medullary (rare, may run in families)
- Anaplastic (rare, an aggressive type of thyroid cancer)
Treatment depends on the type of thyroid cancer and may involve full (or, in rare cases, partial) removal of the thyroid gland during thyroid surgery, radioactive iodine therapy, radiotherapy and chemotherapy. Levothyroxine is prescribed to prevent hypothyroidism after treatment, and is taken for life.
Q: Is there a special thyroid diet?
A: There is no specific thyroid diet that is recommended for people affected by thyroid disorders. A healthy, balanced diet is generally sufficient. It is not advisable to take special supplements without first consulting a medical practitioner.
Some foods and supplements can, however, interfere with the absorption of levothyroxine, so those taking this medication should keep in mind the following:
- After taking calcium-rich foods or supplements, wait four hours before taking levothyroxine
- After taking iron tablets, wait two hours before taking levothyroxine
- Wait as long as possible after taking levothyroxine before eating soya or soy products
In addition, kelp and iodine supplements should be avoided unless otherwise recommended by a healthcare provider, as they can potentially aggravate thyroid disorders. A healthy, varied diet usually provides sufficient amounts of iodine.
Vegetables of the Brassica family, such as cabbage, broccoli and kale, may be implicated in the development of a goiter in some people, but only in very rare cases where consumption is extremely high. It is not a problem under normal dietary conditions.
Q: What is thyroid hair loss?
A: This is the phrase used to describe the loss of hair that may occur in severe, prolonged hypothyroidism or hyperthyroidism. The hair loss tends to affect the entire scalp, as opposed to small areas, and the hair may appear sparse. There may also be loss of eyebrow hair. Thyroid hair loss is unusual in mild thyroid disorders.
The hair typically grows back once the thyroid disorder has been successfully treated. However, this may take a few months, and regrowth is not always complete. Partial hair loss is listed as a possibility during the first few months of treatment with levothyroxine. In rare cases, antithyroid drugs may also be associated with hair loss.
Q: What precautions need to be taken with the thyroid in pregnancy?
A: Normal levels of thyroid hormone in an expectant mother are essential for the healthy development of the baby. People with pre-existing thyroid conditions may need to adjust the dosage of their medication during pregnancy, with regular thyroid function tests to ensure that their thyroid hormone levels are within the optimal range.
In some parts of the world, such as Germany, pregnant people may be encouraged to take iodine supplements to compensate for deficiencies in the soil and the lack of fortification of food products. A doctor will be able to advise on whether supplementation is necessary.
People who develop symptoms of hyperthyroidism or hypothyroidism while pregnant need to seek immediate medical care. If symptoms of postpartum thyroiditis are present after the delivery of the baby, the mother should consult with a medical practitioner. This condition may be mistaken for postpartum depression.
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