goiter

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Goiter

 

Definition

Goiter refers to any visible enlargement of the thyroid gland.

Description

The thyroid gland sits astride the trachea (windpipe) and is shaped like a butterfly. It makes thyroxin, a hormone that regulates the metabolic activity of the body, rather like the gas pedal on a car. Too much thyroxin increases the metabolism, causing weight loss, temperature elevation, nervousness, and irritability. Too little thyroxin slows the metabolism down, deepens the voice, causes weight gain and water retention, and retards growth and mental development in children. Both conditions also alter hair and skin growth, bowel function, and menstrual flow.
Curiously, the thyroid gland is often enlarged whether it is making too much hormone, too little, or sometimes even when it is functioning normally. The thyroid is controlled by the pituitary gland, which secretes thyroid stimulating hormone (TSH) in response to the amount of thyroxin it finds in the blood. TSH increases the amount of thyroxin secreted by the thyroid and also causes the thyroid gland to grow.
  • Hyperthyroid goiter-If the amount of stimulating hormone is excessive, the thyroid will both enlarge and secrete too much thyroxin. The result—hyperthyroidism with a goiter. Graves' disease is the most common form of this disorder.
  • Euthyroid goiter—The thyroid is the only organ in the body to use iodine. If dietary iodine is slightly inadequate, too little thyroxin will be secreted, and the pituitary will sense the deficiency and produce more TSH. The thyroid gland will enlarge enough to make sufficient thyroxin.
  • Hypothyroid goiter—If dietary iodine is severely reduced, even an enlarged gland will not be able to make enough thyroxin. The gland will keep growing under the influence of TSH, but it may never be able to make enough thyroxin.

Causes and symptoms

Excess TSH (or similar hormones), cysts, and tumors will enlarge the thyroid gland. Of these, TSH enlarges the entire gland while cysts and tumors enlarge only a part of it.
The only symptom from a goiter is the large swelling just above the breast bone. Rarely, it may constrict the trachea (windpipe) or esophagus and cause difficulty breathing or swallowing. The rest of the symptoms come from thyroxin or the lack of it.

Diagnosis

The size, shape, and texture of the thyroid gland help the physician determine the cause. A battery of blood tests are required to verify the specific thyroid disease. Functional imaging studies using radioactive iodine determine how active the gland is and what it looks like.

Treatment

Goiters of all types will regress with treatment of the underlying condition. Dietary iodine may be all that is needed. However, if an iodine deficient thyroid that has grown in size to accommodate its deficiency is suddenly supplied an adequate amount of iodine, it could suddenly make large amounts of thyroxin and cause a thyroid storm, the equivalent of racing your car motor at top speed.
Hyperthyroidism can be treated with medications, therapeutic doses of radioactive iodine, or surgical reduction. Surgery is much less common now than it used to be because of progress in drugs and radiotherapy.

Prognosis

Although goiters diminish in size, the thyroid may not return to normal. Sometimes thyroid function does not return after treatment, but thyroxin is easy to take as a pill.

Prevention

Euthyroid goiter and hypothyroid goiter are common around the world because many regions have inadequate dietary iodine, including some places in the United States. International relief groups are providing iodized salt to many of these populations. Because mental retardation is a common result of hypothyroidism in children, this is an extremely important project.

Resources

Organizations

International Council for the Control of Iodine Deficiency Disorders. 43 Circuit Road, Chester Hill, MA, 02167. (207) 335-2221. 〈http://www.tulane.edu/∼icec/icciddhome.htm〉.
Micronutrient Initiative (c/o International Development Research Centre). 250 Albert St., Ottawa, Ontario, Canada K1G 3H9. (613) 236-6163, ext. 2050. 〈http://www.idrc.ca/mi/index.htm〉.

Key terms

Cyst — A liquid-filled structure developing abnormally in the body.
Euthyroid — Having the right amount of thyroxin stimulation.
Hyperthyroid — Having too much thyroxin stimulation.
Hypothyroid — Having too little thyroxin stimulation.
Pituitary gland — The master gland, located in the middle of the head, that controls most of the other glandss by secreting stimulating hormones.
Radiotherapy — The use of ionizing radiation, either as x rays or radioactive isotopes, to treat disease.
Thyroxin — The hormone secreted by the thyroid gland.

goiter

 [goi´ter]
enlargement of the thyroid gland, causing a swelling in the front part of the neck; called also struma. adj., adj goit´rous. If there is evidence of pressure against the throat, or the possibility of a malignancy, the goiter may be removed surgically. Simple endemic goiter is usually caused by lack of iodine in the diet. In graves' disease, goiter is accompanied by excessive thyroid hormones in the blood and symptoms of hyperthyroidism.
aberrant goiter goiter of a supernumerary thyroid gland.
adenomatous goiter that caused by adenoma or multiple colloid nodules of the thyroid gland.
Basedow goiter a colloid goiter that has become hyperfunctioning after administration of iodine.
colloid goiter one that is large and soft and has distended spaces filled with colloid.
cystic goiter one with cysts formed by mucoid or colloid degeneration.
diffuse toxic goiter exophthalmic goiter.
endemic goiter goiter occurring widely in a geographic region where the food or water is deficient in iodine. Treatment consists of iodine replacement; although this will not cure the condition, it can stop it from enlarging, and iodine administered in advance will prevent development of goiter.
exophthalmic goiter any type accompanied by exophthalmos.
fibrous goiter goiter in which the thyroid capsule and stroma are hyperplastic.
follicular goiter parenchymatous goiter.
intrathoracic goiter one with part of the enlarged gland in the thoracic cavity.
iodide goiter that occurring in reaction to iodides at high concentrations, due to inhibition of iodide organification.
multinodular goiter one with circumscribed nodules within the gland.
nontoxic goiter that occurring sporadically and not associated with hyperthyroidism or hypothyroidism.
parenchymatous goiter one with increase in follicles and proliferation of epithelium.
perivascular goiter one that surrounds a large blood vessel.
retrovascular goiter one with processes behind a large blood vessel.
substernal goiter one whose lower part lies beneath the sternum.
suffocative goiter one that causes dyspnea due to pressure.
toxic multinodular goiter hyperthyroidism arising in a multinodular goiter, usually of long standing.
vascular goiter one due chiefly to dilatation of the blood vessels of the thyroid gland.

goi·ter

(goy'tĕr),
A chronic enlargement of the thyroid gland, not due to a neoplasm, occurring endemically in certain localities, especially regions where glaciation occurred and the soil is low in iodine, and sporadically elsewhere.
Synonym(s): struma (1)
[Fr. from L. guttur, throat]

goiter

/goi·ter/ (goi´ter) enlargement of the thyroid gland, causing a swelling in the front part of the neck.goi´trous
aberrant goiter  goiter of a supernumerary thyroid gland.
adenomatous goiter  that caused by adenoma or multiple colloid nodules of the thyroid gland.
Basedow's goiter  a colloid goiter which has become hyperfunctioning after administration of iodine.
colloid goiter  a large, soft goiter with distended spaces filled with colloid.
diffuse toxic goiter  Graves' disease.
diving goiter  one that is movable, sometimes above and sometimes below the sternal notch.
exophthalmic goiter  one accompanied by exophthalmos.
fibrous goiter  one in which the thyroid capsule and stroma are hyperplastic.
follicular goiter  parenchymatous g.
intrathoracic goiter  one in which a portion is in the thoracic cavity.
iodide goiter  that occurring in reaction to iodides at high concentrations, due to inhibition of iodide organification.
lingual goiter  enlargement of the upper end of the thyroglossal duct, forming a tumor at the posterior part of the dorsum of the tongue.
lymphadenoid goiter  Hashimoto's disease.
multinodular goiter  goiter with circumscribed nodules within the gland.
nontoxic goiter  that occurring sporadically and not associated with hyperthyroidism or hypothyroidism.
parenchymatous goiter  one marked by increase in follicles and proliferation of epithelium.
simple goiter  simple hyperplasia of the thyroid gland.
suffocative goiter  one which causes dyspnea by pressure.
wandering goiter  diving g.

goiter

(goi′tər)
n.
A noncancerous enlargement of the thyroid gland, visible as a swelling at the front of the neck, that is often associated with iodine deficiency. Also called struma.

goi′trous (-trəs) adj.

goiter

[goi′ter]
Etymology: L, guttur, throat
an enlarged thyroid gland, usually evident as a pronounced swelling in the neck. The enlargement may be associated with hyperthyroidism, hypothyroidism, or normal levels of thyroid function. It may be cystic or fibrous, containing nodules or an increased number of follicles. The goiter may surround a large blood vessel, or a part of the enlarged gland may be situated beneath the sternum or in the thoracic cavity. Treatment may include total or subtotal surgical removal, the administration of antithyroid drugs or radioiodine, or use of thyroid hormone to block the pituitary mechanism that releases thyroid-stimulating hormone. After thyroidectomy, maintenance therapy with thyroid hormone may be required. Also spelled goitre. See specific goiters. goitrous, adj.
enlarge picture
Goiter

goiter

guttur, Latin, throat Endocrinology A nonneoplastic thyroid enlargement of any cause, which may be euthyroid, hypothyroid, or hyperthyroid, endemic or sporadic, simple–colloid or multinodular; goiters are most often due to ↑ pituitary secretion of TSH, stimulated by ↓ levels of circulating thyroid hormone; congenital goiter occurs in the rare Pendred syndrome–accompanied by deafness or with in utero exposure to antithyroid drugs or iodides; acquired goiter is idiopathic or may be due to goitrogens–eg, lithium carbonate, amiodarone; endemic goiter is subdivided into:
1. A nervous system syndrome, with ataxia, spasticity, deaf-mutism and mental retardation.
2. A myxedematous syndrome characterized by poor growth, mental and sexual development and myxedema; in nodular goiters the lack of available iodine induces hyperplasia with excess colloid being stored in nodular, enlarged follicles; goiters are common in Graves disease in hyperactive middle-aged ♀ and are multinodular and 'hot', displaying hyperactivity on a gallium-67 scan Goitrogenic foods & medications Large amounts of iodine are in seaweed, expectorants–eg SSKI, Lugol's solution–for cough, asthma, COPD, amiodarone–Cardorone, an iodine-rich medication used for arrhythmias. See Toxic multinodular goiter.

goi·ter

(goy'tĕr)
A chronic enlargement of the thyroid gland, not due to a neoplasm, occurring endemically in some localities, especially regions where glaciation occurred and depleted the soil of iodine, and sporadically elsewhere.
Synonym(s): struma, goitre.
[Fr. from L. guttur, throat]

goiter

(goyt'er) [Fr. goitre fr L. guttur, throat]
Enlarge picture
GOITER
Enlargement of the thyroid gland . An enlarged thyroid gland may be caused by thyroiditis, benign thyroid nodules, malignancy, iodine deficiency, or any condition that causes hyperfunction or hypofunction of the gland. Synonym: struma See: illustration

aberrant goiter

A supernumerary goiter.

acute goiter

A goiter that grows rapidly.

adenomatous goiter

An outdated term for multinodular goiter.

colloid goiter

A goiter in which there is a great increase of the follicular contents.

congenital goiter

A goiter present at birth.

cystic goiter

A goiter in which a cyst or cysts are formed, possibly resulting from the degeneration of tissue or liquefaction within an adenoma.

diffuse goiter

A goiter in which the thyroid tissue is diffuse, in contrast to its nodular form as in adenomatous goiter.

diving goiter

A movable goiter, located either below or above the sternal notch.

endemic goiter

Goiter development in certain geographic localities, esp. where the iodine content in food and water is deficient. Goiters are more prevalent in fresh water and lake areas and less so on the seacoast, owing to the lack of iodine in fresh water. The treatment consists of iodine taken orally or in iodized salt.

exophthalmic goiter

Goiter associated with exopthalmos, as in Graves ophthalmopathy.
Synonym: thyroid cachexia

fibrous goiter

A goiter with a hyperplastic capsule.

intrathoracic goiter

A goiter in which a portion of the thyroid tissue lies within the thoracic cavity.

lingual goiter

The abnormal finding of thyroid glandular tissue within the tongue.

multinodular goiter

A goiter having many circumscribed nodules.

nodular goiter

A goiter that contains nodules.

parenchymatous goiter

A usually diffuse goiter characterized by multiplication of cells lining the follicles or alveoli. Colloid is usually reduced and the follicular cavities assume various sizes and are often obliterated by the infoldings of their walls. Fibrous tissue may increase markedly. The iodine content of the gland is low.

perivascular goiter

A goiter surrounding a large blood vessel.

retrovascular goiter

A goiter that develops behind a large blood vessel.

simple goiter

A goiter unaccompanied by constitutional symptoms.

substernal goiter

An enlargement of the lower part of the thyroid isthmus.

suffocative goiter

A goiter that causes shortness of breath owing to pressure.

toxic goiter

An exophthalmic goiter or a goiter in which there is an excessive production of the thyroid hormone.

vascular goiter

A goiter due to distention of the blood vessels of the thyroid gland.

goiter,

n distended thyroid gland, usually manifested as a noticeable bulge in the neck.
Enlarge picture
Goiter.

goi·ter

(goy'tĕr)
Chronic enlargement of the thyroid gland, not due to a neoplasm, occurring endemically in certain localities, where soil is low in iodine.
Synonym(s): struma (1) .
[Fr. from L. guttur, throat]

goiter (goi´tur),

n an enlargement of the thyroid gland.
goiter, colloid,
n (endemic goiter, iodine deficiency goiter, simple goiter) a visible enlargement of the thyroid gland without obvious signs of hypofunction or hyperfunction of the gland resulting from inadequate intake or from an increased demand for iodine.
goiter, endemic,
n See goiter, colloid.
goiter, exophthalmic,
n a disease of the thyroid gland consisting of hyperthyroidism, exophthalmos, and goiterous enlargement of the thyroid gland. A diffuse primary hyperplasia of the thyroid gland of obscure origin; may occur at any age. It produces nervousness, muscular weakness, heat intolerance, tremor, loss of weight, lid lag, and absence of winking and may lead to thyrotoxic heart disease and thyroid crisis.
goiter, iodine deficiency,
n See goiter, colloid.
goiter, nodular, nontoxic,
n the recurrent episodes of hyperplasia and involution of colloid goiter, which result in a multinodular goiter. Symptoms are related to pressure.
goiter, simple,
n See goiter, colloid.

goiter, goitre

enlargement of the thyroid gland, causing a swelling in the front part of the neck.

adenomatous goiter
multilobular goiters cause thyroid enlargement in cats.
colloid goiter
is characterized by the presence of a large soft thyroid gland with its glandular space distended with colloid. Most cases occur in neonatal lambs, calves and kids which show a high rate of stillbirths and weakness and a high mortality rate. Enlarged thyroid glands and alopecia are good indicants of the existence of a nutritional deficiency of iodine, the usual cause of goiter in animals.
dyshormonogenetic goiter
an impairment in thyroglobulin synthesis is thought to be the cause of inherited, congenital goiter recorded in sheep, cattle and goats. The thyroid gland is enlarged, there is a high neonatal mortality, a silky wool in sheep and a rough, sparse haircoat in goats. Called also inherited goiter.
goitrogen-induced goiter
there are a number of goitrogens in the environment of grazing animals. Their effect is almost entirely on the newborn. Common agents are low level intakes of cyanogenetic glycosides, e.g. in white clover, the glucosinolates in Brassica spp. plants, and mimosine in Leucaena leucocephala.
hyperplastic goiter
diffuse hyperplasia is the standard response to dietary iodine deficiency and to poisoning by plant goitrogens. It may also be caused by persistent exposure of the fetus to a high iodine intake of the dam. See also iodide goiter (below). Neonates are the usual subjects and the disease is manifested by clinical goiter, often sufficient to cause dystocia, and weak neonates with a high rate of stillbirths and deaths soon after birth.
inherited goiter
see dyshormonogenetic goiter (above).
iodide goiter
that occurring in reaction to iodides at high concentrations, due to inhibition of iodide organification.
nodular goiter
an endocrinologically inactive nodular enlargement of the thyroids in old dogs and horses. In old cats similar goiters sometimes develop functional adenomas.