Goitre | |
---|---|
Other names | Goiter |
Diffuse hyperplasia of the thyroid | |
Specialty | Endocrinology |
A goitre, or goiter, is a swelling in the neck resulting from an enlarged thyroid gland. [1] [2] A goitre can be associated with a thyroid that is not functioning properly.
Worldwide, over 90% of goitre cases are caused by iodine deficiency. [3] The term is from the Latin gutturia, meaning throat. Most goitres are not cancerous (benign), though they may be potentially harmful.
A goitre can present as a palpable or visible enlargement of the thyroid gland at the base of the neck. A goitre, if associated with hypothyroidism or hyperthyroidism, may be present with symptoms of the underlying disorder. For hyperthyroidism, the most common symptoms are associated with adrenergic stimulation: tachycardia (increased heart rate), palpitations, nervousness, tremor, increased blood pressure and heat intolerance. Clinical manifestations are often related to hypermetabolism (increased metabolism), excessive thyroid hormone, an increase in oxygen consumption, metabolic changes in protein metabolism, immunologic stimulation of diffuse goitre, and ocular changes (exophthalmos). [4] Hypothyroid people commonly have poor appetite, cold intolerance, constipation, lethargy and may undergo weight gain. However, these symptoms are often non-specific and make diagnosis difficult.[ citation needed ]
According to the WHO classification of goitre by palpation, the severity of goitre is currently graded as grade 0, grade 1, grade 2. [5]
Worldwide, the most common cause for goitre is iodine deficiency, commonly seen in countries that scarcely use iodized salt. Selenium deficiency is also considered a contributing factor. In countries that use iodized salt, Hashimoto's thyroiditis is the most common cause. [6] Goitre can also result from cyanide poisoning, which is particularly common in tropical countries where people eat the cyanide-rich cassava root as the staple food. [7]
Cause | Pathophysiology | Resultant thyroid activity | Growth pattern | Treatment | Incidence and prevalence | Prognosis |
---|---|---|---|---|---|---|
Iodine deficiency | Hyperplasia of thyroid to compensate for decreased efficacy | Can cause hypothyroidism | Diffuse | Iodine | Constitutes over 90% cases of goitre worldwide [3] | Increased size of thyroid may be permanent if untreated for around five years |
Congenital hypothyroidism | Inborn errors of thyroid hormone synthesis | Hypothyroidism | ||||
Goitrogen ingestion | ||||||
Adverse drug reactions | ||||||
Hashimoto's thyroiditis | Autoimmune disease in which the thyroid gland is gradually destroyed. Infiltration of lymphocytes. | Hypothyroidism | Diffuse and lobulated [8] | Thyroid hormone replacement | Prevalence: 1 to 1.5 in a 1000 | Remission with treatment |
Pituitary disease | Hypersecretion of thyroid stimulating hormone, almost always by a pituitary adenoma [9] | Diffuse | Pituitary surgery | Very rare [9] | ||
Graves' disease—also called Basedow syndrome | Autoantibodies (TSHR-Ab) that activate the TSH-receptor (TSHR) | Hyperthyroidism | Diffuse | Antithyroid agents, radioiodine, surgery | Will develop in about 0.5% of males and 3% of females | Remission with treatment, but still lower quality of life for 14 to 21 years after treatment, with lower mood and lower vitality, regardless of the choice of treatment [10] |
Thyroiditis | Acute or chronic inflammation | Can be hyperthyroidism initially, but progress to hypothyroidism | ||||
Thyroid cancer | Usually uninodular | Overall relative 5-year survival rate of 85% for females and 74% for males [11] | ||||
Benign thyroid neoplasms | Usually hyperthyroidism | Usually uninodular | Mostly harmless [12] | |||
Thyroid hormone insensitivity | Secretional hyperthyroidism, Symptomatic hypothyroidism | Diffuse |
Goitre may be diagnosed via a thyroid function test in an individual suspected of having it. [13]
A goitre may be classified either as nodular or diffuse. Nodular goitres are either of one nodule (uninodular) or of multiple nodules (multinodular). [14] Multinodular goiter (MNG) is the most common disorder of the thyroid gland. [15]
Goitre is treated according to the cause. If the thyroid gland is producing an excess of thyroid hormones (T3 and T4), radioactive iodine is given to the patient to shrink the gland. If goitre is caused by iodine deficiency, small doses of iodide in the form of Lugol's iodine or KI solution are given. If the goitre is associated with an underactive thyroid, thyroid supplements are used as treatment. Sometimes a partial or complete thyroidectomy is required. [19]
The discovery of iodine's importance in thyroid function and its role in preventing goiter marked a significant medical breakthrough. The introduction of iodized salt in the early 20th century became a key public health initiative, effectively reducing the prevalence of goiter in previously affected regions. This measure was one of the earliest and most successful examples of mass preventive health campaigns. [20]
Goitre is more common among women, but this includes the many types of goitre caused by autoimmune problems, and not only those caused by simple lack of iodine. [22]
Iodine mainly accumulates in the sea and in the topsoil. Before iodine enrichment programs, goiters were common in areas with repeated flooding or glacial activities, which erodes the topsoil. It is endemic in populations where the intake of iodine is less than 10 μg per day. [23]
Examples of such regions include the alpine regions of Southern Europe (such as Switzerland), the Himalayans, the Great Lakes basin, etc. As reported in 1923, all the domestic animals have goiter in some of the glacial valleys of Southern Alaska. It was so severe in Pemberton Meadows that it was difficult to raise young animals there. [24]
Chinese physicians of the Tang dynasty (618–907) were the first to successfully treat patients with goitre by using the iodine-rich thyroid gland of animals such as sheep and pigs—in raw, pill, or powdered form. [25] This was outlined in Zhen Quan's (d. 643 AD) book, as well as several others. [25] One Chinese book, The Pharmacopoeia of the Heavenly Husbandman, asserted that iodine-rich sargassum was used to treat goitre patients by the 1st century BC, but this book was written much later. [25]
In the 12th century, Zayn al-Din al-Jurjani, a Persian physician, provided the first description of Graves' disease after noting the association of goitre and a displacement of the eye known as exophthalmos in his Thesaurus of the Shah of Khwarazm, the major medical dictionary of its time. [26] [27] The disease was later named after Irish doctor Robert James Graves, who described a case of goitre with exophthalmos in 1835. The German Karl Adolph von Basedow also independently reported the same constellation of symptoms in 1840, while earlier reports of the disease were also published by the Italians Giuseppe Flajani and Antonio Giuseppe Testa, in 1802 and 1810 respectively, [28] and by the English physician Caleb Hillier Parry (a friend of Edward Jenner) in the late 18th century. [29]
Paracelsus (1493–1541) was the first person to propose a relationship between goitre and minerals (particularly lead) in drinking water. [30] Iodine was later discovered by Bernard Courtois in 1811 from seaweed ash. [31]
Goitre was previously common in many areas that were deficient in iodine in the soil. For example, in the English Midlands, the condition was known as Derbyshire Neck. In the United States, goitre was found in the Appalachian, [32] [33] Great Lakes, Midwest, and Intermountain regions. The condition is now practically absent in affluent nations, where table salt is supplemented with iodine. However, it is still prevalent in India, China, [34] Central Asia, and Central Africa.
Goitre had been prevalent in the alpine countries for a long time. Switzerland reduced the condition by introducing iodized salt in 1922. The Bavarian tracht in the Miesbach and Salzburg regions, which appeared in the 19th century, includes a choker, dubbed Kropfband (struma band) which was used to hide either the goitre or the remnants of goitre surgery. [35]
In various regions around the world, particularly in mountainous areas, the prevalence of goiter was linked to iodine deficiency in the diet. For example, the Alps, the Himalayas, and the Andes had high rates of goiter due to the iodine-poor soil. In these regions, iodine deficiency led to widespread hormonal imbalances, particularly affecting thyroid function. [36]
In the 1920s wearing bottles of iodine around the neck was believed to prevent goitre. [37]
The coat of arms and crest of Die Kröpfner, of Tyrol, showed a man "afflicted with a large goitre", an apparent pun on the German for the word ("Kropf"). [41]
In some historical contexts, goiters were so prevalent that they became normalized within the culture. For instance, in certain Alpine regions, large goiters were sometimes considered a sign of beauty. Conversely, in other areas, individuals with goiters faced social stigma, which could lead to marginalization and discrimination. [42]
Goiter, resulting primarily from iodine deficiency, has historically been a widespread condition with significant health and social implications. Advances in nutrition and public health have greatly reduced its prevalence, but understanding its historical context helps in appreciating the development of endocrinology and public health measures.
Congenital iodine deficiency syndrome (CIDS), also called cretinism, is a medical condition present at birth marked by impaired physical and mental development, due to insufficient thyroid hormone production (hypothyroidism) often caused by insufficient dietary iodine during pregnancy. It is one cause of underactive thyroid function at birth, called congenital hypothyroidism. If untreated, it results in impairment of both physical and mental development. Symptoms may include: goiter, poor length growth in infants, reduced adult stature, thickened skin, hair loss, enlarged tongue, a protruding abdomen, delayed bone maturation and puberty in children, mental deterioration, neurological impairment, impeded ovulation, and infertility in adults.
Hyperthyroidism is the condition that occurs due to excessive production of thyroid hormones by the thyroid gland. Thyrotoxicosis is the condition that occurs due to excessive thyroid hormone of any cause and therefore includes hyperthyroidism. Some, however, use the terms interchangeably. Signs and symptoms vary between people and may include irritability, muscle weakness, sleeping problems, a fast heartbeat, heat intolerance, diarrhea, enlargement of the thyroid, hand tremor, and weight loss. Symptoms are typically less severe in the elderly and during pregnancy. An uncommon but life-threatening complication is thyroid storm in which an event such as an infection results in worsening symptoms such as confusion and a high temperature; this often results in death. The opposite is hypothyroidism, when the thyroid gland does not make enough thyroid hormone.
The thyroid, or thyroid gland, is an endocrine gland in vertebrates. In humans, it is in the neck and consists of two connected lobes. The lower two thirds of the lobes are connected by a thin band of tissue called the isthmus (pl.: isthmi). The thyroid gland is a butterfly-shaped gland located in the neck below the Adam's apple. Microscopically, the functional unit of the thyroid gland is the spherical thyroid follicle, lined with follicular cells (thyrocytes), and occasional parafollicular cells that surround a lumen containing colloid. The thyroid gland secretes three hormones: the two thyroid hormones – triiodothyronine (T3) and thyroxine (T4) – and a peptide hormone, calcitonin. The thyroid hormones influence the metabolic rate and protein synthesis and growth and development in children. Calcitonin plays a role in calcium homeostasis. Secretion of the two thyroid hormones is regulated by thyroid-stimulating hormone (TSH), which is secreted from the anterior pituitary gland. TSH is regulated by thyrotropin-releasing hormone (TRH), which is produced by the hypothalamus.
Graves' disease, also known as toxic diffuse goiter or Basedow’s disease, is an autoimmune disease that affects the thyroid. It frequently results in and is the most common cause of hyperthyroidism. It also often results in an enlarged thyroid. Signs and symptoms of hyperthyroidism may include irritability, muscle weakness, sleeping problems, a fast heartbeat, poor tolerance of heat, diarrhea and unintentional weight loss. Other symptoms may include thickening of the skin on the shins, known as pretibial myxedema, and eye bulging, a condition caused by Graves' ophthalmopathy. About 25 to 30% of people with the condition develop eye problems.
Hypothyroidism is a disorder of the endocrine system in which the thyroid gland does not produce enough thyroid hormones. It can cause a number of symptoms, such as poor ability to tolerate cold, extreme fatigue, muscle aches, constipation, slow heart rate, depression, and weight gain. Occasionally there may be swelling of the front part of the neck due to goitre. Untreated cases of hypothyroidism during pregnancy can lead to delays in growth and intellectual development in the baby or congenital iodine deficiency syndrome.
A thyroidectomy is an operation that involves the surgical removal of all or part of the thyroid gland. In general surgery, endocrine or head and neck surgeons often perform a thyroidectomy when a patient has thyroid cancer or some other condition of the thyroid gland or goiter. Other indications for surgery include cosmetic, or symptomatic obstruction. Thyroidectomy is a common surgical procedure that has several potential complications or sequelae including: temporary or permanent change in voice, temporary or permanently low calcium, need for lifelong thyroid hormone replacement, bleeding, infection, and the remote possibility of airway obstruction due to bilateral vocal cord paralysis. Complications are uncommon when the procedure is performed by an experienced surgeon.
Hashimoto's thyroiditis, also known as chronic lymphocytic thyroiditis and Hashimoto's disease, is an autoimmune disease in which the thyroid gland is gradually destroyed. A slightly broader term is autoimmune thyroiditis, identical other than that it is also used to describe a similar condition without a goiter.
Iodised salt is table salt mixed with a minute amount of various salts of the element iodine. The ingestion of iodine prevents iodine deficiency. Worldwide, iodine deficiency affects about two billion people and is the leading preventable cause of intellectual and developmental disabilities. Deficiency also causes thyroid gland problems, including endemic goitre. In many countries, iodine deficiency is a major public health problem that can be cheaply addressed by purposely adding small amounts of iodine to the sodium chloride salt.
Iodine deficiency is a lack of the trace element iodine, an essential nutrient in the diet. It may result in metabolic problems such as goiter, sometimes as an endemic goiter as well as congenital iodine deficiency syndrome due to untreated congenital hypothyroidism, which results in developmental delays and other health problems. Iodine deficiency is an important global health issue, especially for fertile and pregnant women. It is also a preventable cause of intellectual disability.
The Jod-Basedow effect is hyperthyroidism following administration of iodine or iodide, either as a dietary supplement, for iodinated contrast medical imaging, or as a medication.
Thyroid disease is a medical condition that affects the function of the thyroid gland. The thyroid gland is located at the front of the neck and produces thyroid hormones that travel through the blood to help regulate many other organs, meaning that it is an endocrine organ. These hormones normally act in the body to regulate energy use, infant development, and childhood development.
Thyroiditis is the inflammation of the thyroid gland. The thyroid gland is located on the front of the neck below the laryngeal prominence, and makes hormones that control metabolism.
Toxic multinodular goiter (TMNG), also known as multinodular toxic goiter (MNTG), is an active multinodular goiter associated with hyperthyroidism.
Endocrine diseases are disorders of the endocrine system. The branch of medicine associated with endocrine disorders is known as endocrinology.
A thyroid adenoma is a benign tumor of the thyroid gland, that may be inactive or active as a toxic adenoma.
Thyroid nodules are nodules which commonly arise within an otherwise normal thyroid gland. They may be hyperplastic or tumorous, but only a small percentage of thyroid tumors are malignant. Small, asymptomatic nodules are common, and often go unnoticed. Nodules that grow larger or produce symptoms may eventually need medical care. A goitre may have one nodule – uninodular, multiple nodules – multinodular, or be diffuse.
Iodine deficiency is a widespread problem in western, southern and eastern parts of China, as their iodized salt intake level is much lower than the average national level. Iodine deficiency is a range of disorders that affect many different populations. It is estimated that IDDs affect between 800 million and 2 billion people worldwide; countries have spent millions of dollars in implementing iodized salt as a means to counteract the iodine deficiencies prevalent today. With China accounting for "40% of the total population", it bears a large portion of those who are iodine deficient.
Thyroid disease in pregnancy can affect the health of the mother as well as the child before and after delivery. Thyroid disorders are prevalent in women of child-bearing age and for this reason commonly present as a pre-existing disease in pregnancy, or after childbirth. Uncorrected thyroid dysfunction in pregnancy has adverse effects on fetal and maternal well-being. The deleterious effects of thyroid dysfunction can also extend beyond pregnancy and delivery to affect neurointellectual development in the early life of the child. Due to an increase in thyroxine binding globulin, an increase in placental type 3 deioidinase and the placental transfer of maternal thyroxine to the fetus, the demand for thyroid hormones is increased during pregnancy. The necessary increase in thyroid hormone production is facilitated by high human chorionic gonadotropin (hCG) concentrations, which bind the TSH receptor and stimulate the maternal thyroid to increase maternal thyroid hormone concentrations by roughly 50%. If the necessary increase in thyroid function cannot be met, this may cause a previously unnoticed (mild) thyroid disorder to worsen and become evident as gestational thyroid disease. Currently, there is not enough evidence to suggest that screening for thyroid dysfunction is beneficial, especially since treatment thyroid hormone supplementation may come with a risk of overtreatment. After women give birth, about 5% develop postpartum thyroiditis which can occur up to nine months afterwards. This is characterized by a short period of hyperthyroidism followed by a period of hypothyroidism; 20–40% remain permanently hypothyroid.
Amiodarone induced thyrotoxicosis (AIT) is a form of hyperthyroidism due to treatment with antiarrhythmic drug, amiodarone.
Feline hyperthyroidism is an endocrine disorder in which the thyroid gland produces too much thyroid hormone. Hyperthyroidism is the most common endocrinopathy of cats. The complete pathogenesis is not fully understood.
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