goiter

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.

Gale Encyclopedia of Medicine. Copyright 2008 The Gale Group, Inc. All rights reserved.

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.

Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.

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]

Farlex Partner Medical Dictionary © Farlex 2012

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.

The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.

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.

McGraw-Hill Concise Dictionary of Modern Medicine. © 2002 by The McGraw-Hill Companies, Inc.

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]

Medical Dictionary for the Health Professions and Nursing © Farlex 2012

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]

Medical Dictionary for the Dental Professions © Farlex 2012