Thyro Health Dictionary

Thyro: From 1 Different Sources


Thyrotoxicosis

A pathologic thyroid hyperfunction. It is sometimes referred to as exophthalmic goiter. An overt disease, sometimes life-threatening, it is very different from the moderately elevated basal metabolism some constitutional types manifest under stress.... thyrotoxicosis

Thyroid Cancer

A rare disease that accounts for around 1 per cent of all cancers, cancer of the THYROID GLAND usually presents as an isolated hard nodule in the neck. The rate at which the nodule grows depends upon the patient’s age and type of cancer cell. Pain is not usually a feature, but the increasing size may result in the tumour pressing on vital structures in the neck – for example, the nerves controlling the LARYNX (resulting in hoarseness) and the PHARYNX (causing di?culty in swallowing). If more than one nodule is present, they are likely to be benign, not malignant. Treatment is by surgical removal after which the patient will need to take THYROXINE for the rest of his or her life. Radioactive iodine is usually given after surgery to destroy any residual cancerous cells. If treated early, the outlook is good.... thyroid cancer

Thyroid Gland

A highly vascular organ situated in front of the neck. It consists of a narrow isthmus crossing the windpipe close to its upper end, and joining together two lateral lobes which run upwards, one on each side of the LARYNX. The gland is therefore shaped somewhat like a horseshoe, each lateral lobe being about 5 cm (2 inches) long and the isthmus about 12 mm (••• inch) wide, and it is ?rmly bound to the larynx. The weight of the thyroid gland is about 28·5 grams (1 ounce), but it is larger in females than in males and in some women increases in size during MENSTRUATION. It often reaches an enormous size in the condition known as GOITRE (see also THYROID GLAND, DISEASES OF).

Function The chief function of the thyroid gland is to produce a hormone (see HORMONES) rich in iodine – THYROXINE, which controls the rate of body METABOLISM. Thus, if it is de?cient in infants they fail to grow and suffer LEARNING DISABILITY, a condition formerly known as CRETINISM. If the de?ciency develops in adult life, the individual becomes obese, lethargic, and develops a coarse skin, a condition known as hypothyroidism (see under THYROID GLAND, DISEASES OF). Overactivity of the thyroid, or hyperthyroidism, results in loss of weight, rapid heart action, anxiety, overactivity and increased appetite. (See THYROID GLAND, DISEASES OF – Thyrotoxicosis.)

The production of the thyroid hormone is controlled by a hormone of the PITUITARY GLAND – the thyrotrophic hormone.... thyroid gland

Thyroidectomy

Surgical removal of the THYROID GLAND. Partial thyroidectomy – removal of part of the gland – is sometimes done in patients with hyperthyroidism (see under THYROID GLAND, DISEASES OF) when drug treatment has failed to control the disorder.... thyroidectomy

Thyroiditis

See under THYROID GLAND, DISEASES OF.... thyroiditis

Thyroxine

(T4) A crystalline substance, containing IODINE, isolated from the THYROID GLAND and possessing the properties of thyroid extract. It has also been synthesised. It is used in patients with defective function of the thyroid, such as myxoedema (see THYROID GLAND, DISEASES OF

– Hypothyroidism).... thyroxine

Thyroglobulin

The iodine-containing protein that is stored in the thyroid gland. It is converted into circulating thyroxines when the thyroid is stimulated by TSH (Thyroid Stimulating Hormone) from the pituitary (in turn stimulated by the hypothalamus, where thyroxine levels are actually monitored). See: T4... thyroglobulin

Thyroid Cartilage

The largest cartilage in the LARYNX and forms the prominence of the Adam’s apple in front of the neck.... thyroid cartilage

Thyroid Gland, Diseases Of

... thyroid gland, diseases of

Thyrotrophin-releasing Hormone (trh)

A hormone (see HORMONES) produced and released by the HYPOTHALAMUS which stimulates the release of THYROTROPHINSTIMULATING HORMONE (TSH) by the PITUITARY GLAND.... thyrotrophin-releasing hormone (trh)

Thyrotrophin-stimulating Hormone (tsh)

A hormone (see HORMONES) manufactured and released by the anterior part of the PITUITARY GLAND which stimulates the THYROID GLAND to manufacture and release thyroid hormones (THYROXINE and TRI-IODOTHYRONINE).... thyrotrophin-stimulating hormone (tsh)

Hashimoto’s Thyroiditis

An autoimmune disorder in which the body’s immune system develops antibodies against its own thyroid gland cells. As a result, the thyroid gland cannot produce enough thyroid hormones, a condition known as hypothyroidism. The principal symptoms of Hashimoto’s thyroiditis are tiredness, muscle weakness, and weight gain, and the thyroid gland becomes enlarged.

Diagnosis is confirmed by blood tests.

Treatment is by thyroid hormone replacement therapy, which is life-long.... hashimoto’s thyroiditis

Thyroglossal Disorders

A set of congenital defects caused by failure of the thyroglossal duct to disappear during embryonic development. In embryos, this duct runs from the base of the tongue to the thyroid gland. Abnormal development may cause the duct to persist in its entirety or partly as a cyst. A cyst usually becomes infected and swollen, which may lead to formation of a fistula. The cyst and any remaining parts of the duct are removed.... thyroglossal disorders

Thyroid-function Tests

A group of blood tests used to evaluate the function of the thyroid gland and to detect or confirm any thyroid disorder. The thyroid hormones T3 and T4 are measured, as well as thyroid-stimulating hormone (TSH), the pituitary gland hormone that stimulates the thyroid gland.... thyroid-function tests

Thyroid Scanning

Techniques, such as radionuclide scanning and ultrasound scanning, that are used to provide information about the location, anatomy, and function of the thyroid gland.... thyroid scanning

Thyrocalcitonin

n. see calcitonin.... thyrocalcitonin

Thyroid Gland, Disorders Of

Disorders of the thyroid gland may cause hyperthyroidism, hypothyroidism, or enlargement or distortion of the gland. Myxoedema, Graves’ disease, and Hashimoto’s thyroiditis are common disorders. Goitre may sometimes occur with no accompanying abnormality of thyroid function. In rare cases, the gland is absent at birth, producing severe cretinism. Sometimes it develops in an abnormal position in the neck, causing, in rare cases, difficulty in swallowing or breathing.

A genetic disorder may impair the thyroid’s ability to secrete hormones and goitre may result. Thyroid infection is uncommon and leads to thyroiditis. Viral infection can cause extreme pain and temporary hyperthyroidism. Hormonal changes during puberty or pregnancy may cause a degree of goitre temporarily. Hyperthyroidism due to excessive production of by the pituitary gland is rare but can occur as a result of a pituitary tumour.

Because iodine is necessary for the production of thyroid hormone, its deficiency may lead to goitre. Severe iodine deficiency in children may cause myxoedema. (See also thyroid cancer.)

thyroid hormones The 3 hormones produced by the thyroid gland are thyroxine (T4) and triiodothyronine (T3), which regulate metabolism, and calcitonin, which helps to regulate calcium levels in the body.... thyroid gland, disorders of

Thyrocele

n. a swelling of the thyroid gland. See goitre.... thyrocele

Thyrohyoid

adj. relating to the thyroid cartilage and hyoid bone. The thyrohyoid ligaments form part of the *larynx; contraction of the thyrohyoid muscle raises the larynx.... thyrohyoid

Thyroid Acropachy

a rarely seen but well-documented alteration in the shape of the nails resembling *clubbing but unique to Graves’ disease (see thyrotoxicosis). It is often associated with formation of new bone seen on X-rays of the hands and wrists, which is said to resemble bubbles along the surface of the bones.... thyroid acropachy

Thyroid Antibodies

autoantibodies directed against the cells of the thyroid gland, which serve as a marker of autoimmune thyroid disease. There are two main types: antibodies directed against the thyroid peroxidise (TPO) enzyme; and anti-thyroglobulin, directed against the thyroid colloid (see thyroid gland). The highest level of thyroid antibodies is found in *Hashimoto’s disease.... thyroid antibodies

Thyroid Crisis

(thyroid storm) a life-threatening condition due to an acute and severe exacerbation of previously undiagnosed or inadequately treated *thyrotoxicosis. It often follows infections, childbirth, nonthyroid surgery, or trauma but can occur without an obvious cause. The presenting features are a fever, severe agitation, nausea and vomiting, diarrhoea, and abdominal pains. An accelerated heart rate and irregularity of the heart rhythm can cause heart failure, and psychotic episodes or coma can result. Blood tests will reveal hyperthyroidism and may also show altered liver function, high blood sugar, high calcium levels, a high white blood cell count, and often anaemia. Treatment is with intravenous fluids, oxygen, antithyroid drugs (such as *carbimazole or *propylthiouracil), high-dose iodide solution (see Lugol’s solution), high-dose steroids, and beta blockers. The patient must be cooled and given antipyretics, such as paracetamol. Any underlying cause must also be treated.... thyroid crisis

Thyroid Hormone

an iodine-containing substance, synthesized and secreted by the thyroid gland, that is essential for normal metabolic processes and mental and physical development. There are two thyroid hormones, *triiodothyronine and *thyroxine, which are formed from *thyroglobulin. Lack of these hormones gives rise to *cretinism in infants and *myxoedema in adults. Excessive production of thyroid hormones gives rise to *thyrotoxicosis.... thyroid hormone

Thyroid-stimulating Hormone

(TSH, thyrotrophin) a hormone, synthesized and secreted by the anterior pituitary gland under the control of *thyrotrophin-releasing hormone, that stimulates activity of the thyroid gland. Raised levels of TSH are found in primary *hypothyroidism. Normal or low TSH levels in the presence of a low serum thyroxine are found in secondary hypothyroidism and the *euthyroid sick syndrome.... thyroid-stimulating hormone

Thyroid Storm

see thyroid crisis.... thyroid storm

Thyroplasty

n. a surgical procedure performed on the thyroid cartilage of the larynx to alter the characteristics of the voice.... thyroplasty

Thyrotomy

n. surgical incision of either the thyroid cartilage in the neck or of the thyroid gland itself.... thyrotomy

Thyrotoxic Periodic Paralysis

a condition in which attacks of sudden weakness and flaccidity occur in patients with *thyrotoxicosis, seen most often in males of Asian descent. The attacks last from hours to days; they can be prevented by potassium supplements and subsequent treatment of the thyrotoxicosis.... thyrotoxic periodic paralysis

Thyrotrophin

n. see thyroid-stimulating hormone.... thyrotrophin

Thyrotrophin-releasing Hormone

(TRH) a hormone from the hypothalamus (in the brain) that acts on the anterior pituitary gland to stimulate the release of *thyroid-stimulating hormone. A preparation of TRH (protirelin) may be given by intravenous injection to test thyroid gland function and to estimate reserves of thyroid-stimulating hormone in the pituitary.... thyrotrophin-releasing hormone



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