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2. pertaining to the thyroid gland.
4. a preparation of thyroid gland from domesticated food animals, containing levothyroxine and liothyronine and used as replacement therapy in the diagnosis and treatment of hypothyroidism and the prevention and treatment of goiter and thyroid carcinoma; administered orally.
thyroid crisis a sudden and dangerous increase of the symptoms of thyrotoxicosis, seen in patients with severe hyperthyroidism or in the period immediately following a thyroidectomy. (However, good postoperative care and the use of radioiodine ablation techniques have greatly reduced the incidence of this once common postoperative complication.) Called also thyroid or thyrotoxic storm.

Thyroid crisis is a serious event that can be fatal if not brought under control. All of the body processes are accelerated to dangerously high levels. The pulse may rise to 200 beats per minute, and there is concurrent rise in the respiratory rate. The temperature control center loses control, bringing about a rapid and steady increase in body temperature. Pulmonary edema and congestive heart failure can also occur.

Treatment is aimed at correction of the hyperthyroidism, control of the symptoms, and prevention of further crisis by treating the underlying cause. Medications are employed to block synthesis of thyroid hormones, block their release, and inhibit conversion of triiodothyronine to thyroxine. plasmapheresis. plasma exchange, or hemodialysis may be necessary to remove the hormones from the circulation.

Supportive care includes administration of oxygen and measures to control hyperthermia, such as the use of ice packs or a hyperthermia blanket. Intravenous hydration is important to prevent shock. The use of glucocorticoids is associated with improved survival rates. propranolol, sympatholytics, and guanethidine are often used, as well as other medications that treat symptoms.
thyroid function test a test of the functioning of the thyroid gland, such as its proper production of thyroid hormones. See radioiodineuptake test, thyroid-stimulating hormone test, thyrotropin-releasing hormone test, and triiodothyronine resin uptake test.
thyroid gland the largest of the endocrine glands, consisting of two lateral lobes connected by an isthmus; a third pyramidal lobe sometimes extends up from the isthmus. The thyroid gland is located in the front and sides of the neck just below the thyroid cartilage and produces hormones that are vital in maintaining normal growth and metabolism (see thyroid hormones). It also serves as a storehouse for iodine.

Diagnostic tests for thyroid disorders include radioimmunoassay for T3, T4, and thyroid-stimulating hormone (TSH), free thyroxine serum concentration, and free thyroxine index (FTI). These and other thyroid function tests can be distorted by preparations and foods containing iodine, and by oral contraceptives, phenytoin (Dilantin), and several other drugs. The thyroid scan is useful in detecting nodules and active thyroid tissue and, combined with radioactive iodine uptake, measures the ability of the thyroid gland to take in ingested iodine.

Persons who received radiation to the head and neck as children are at higher than normal risk for development of thyroid abnormalities. Of these disorders about one-third are carcinomas of the thyroid. Other problems related to radiation early in life include adenomas and other malignant and benign tumors, hypo- and hyperthyroidism, and thyroiditis. The American Thyroid Association suggests periodic laboratory testing and physical assessment of persons at high risk in order to detect these abnormalities when they are more amenable to treatment.
Thyroid gland.
thyroid hormones iodothyronines secreted by the thyroid gland, principally thyroxine (tetraiodothyronine or T4) and triiodothyronine (T3). The serum level of T4 is normally 45 to 50 times the level of T3. However, T3 is several times more active than T4, and most T3 is produced by metabolism of T4 in peripheral tissues. The pharmaceutical names for T4 and T3 are levothyroxine and liothyronine, respectively. Thyroid hormones influence many metabolic processes. They stimulate the cellular production of heat; stimulate protein synthesis; regulate many aspects of carbohydrate metabolism; stimulate lipid synthesis, mobilization, and degradation; stimulate the synthesis of coenzymes from vitamins; and may affect the response of tissues to epinephrine and norepinephrine.

Secretion of thyroid hormones is regulated by the hypothalamus-pituitary-thyroid control system. Internal environmental conditions, such as low thyroid hormone and norepinephrine serum levels, or external factors, such as cold and stress, activate the hypothalamus, which secretes thyrotropin-releasing hormone (TRH). This hormone acts on the pituitary gland and brings about the release of thyroid-stimulating hormone (TSH). The TSH then stimulates the release of thyroid hormones such as T3 and T4 from the thyroid gland. When sufficient levels of serum thyroxine and other thyroid hormones have been reached, there is negative feedback to the hypothalamus and TRH is no longer secreted. See also hypothyroidism and hyperthyroidism.
thyroid-stimulating hormone test a thyroid function test in which thyrotropin (thyroid-stimulating hormone) is administered intramuscularly and the thyroid gland is monitored over time with scintiscanning or radioimmunoassays for a response or areas of decreased responsiveness. Called also TSH test and TSH stimulation test.


1. Resembling a shield; denoting a gland (thyroid gland) and a cartilage of the larynx (thyroid cartilage) having such a shape.
2. The cleaned, dried, and powdered thyroid gland obtained from one of the domesticated animals used for food and containing 0.17-0.23% of iodine; formerly widely used in the treatment of hypothyroidism, cretinism, and myxedema, in some cases of obesity, and in skin disorders.
[G. thyreoeidēs, fr. thyreos, an oblong shield, + eidos, form]


/thy·roid/ (thi´roid)
1. the thyroid gland; see under gland.
2. pertaining to the thyroid gland.
4. a preparation of thyroid gland from domesticated food animals, containing levothyroxine and liothyronine and used as replacement therapy in the diagnosis and treatment of hypothyroidism and the prophylaxis and treatment of goiter and thyroid carcinoma.


1. The thyroid gland.
2. The thyroid cartilage.
3. A dried, powdered preparation of the thyroid gland of certain domestic animals, used in treatment of hypothyroid conditions.
4. An artery, vein, nerve, or other part associated with the thyroid gland or thyroid cartilage.

thy′roid′ adj.
thy·roi′dal adj.



adjective Relating to the thyroid gland noun
1. Thyroid gland extract.
2. Thyroid gland, see there.


Resembling a shield; denoting a gland (thyroid gland) and a cartilage of the larynx (thyroid cartilage) having such a shape.
[G. thyreoeidēs, fr. thyreos, an oblong shield, + eidos, form]


A gland in the neck overlying the windpipe that regulates the speed of metabolic processes by producing a hormone, thyroxin.


shield-shaped gland in anterior neck; secretes thyroid hormone (thyroxine, i.e. T4 and T3) and calcitonin


1. resembling a shield.
2. the thyroid gland (see below) secreting thyroid hormones (see below).
3. a pharmaceutical preparation of cleaned, dried, powdered thyroid gland, obtained from those domesticated animals used for food by humans.

accessory thyroid
an additional thyroid located anywhere from the larynx to diaphragm, e.g. intrapericordial aorta; may be sufficient to supply the patient's need of thyroid hormone. Most common in dogs.
thyroid C cell
see c cell.
thyroid cartilage
the shield-shaped cartilage of the larynx.
thyroid diverticulum
primordium of the thyroid gland; appears as an outgrowth of the foregut between the first two pharyngeal pouches. This tube of epithelial cells grows ventrally into mesenchyme; the tube becomes the thyroglossal duct, the tip divides into two lobes, the thyroid glands.
thyroid dysfunction
ectopic thyroid
migration of thyroid diverticulum tissue to aberrant sites occurs, e.g. thyroid tissue in the thymus. These cause no apparent abnormality.
thyroid extract
a pharmaceutical substance derived from thyroid glands, used in the treatment of hypothyroidism. See thyroid (3) (above).
thyroid function tests
used to assess the functional capacity of the thyroid glands; most commonly employed in dogs and cats. Include plasma T4, plasma T3, free T4 radioiodine uptake, and TSH response tests.
thyroid gland
the largest of the endocrine glands, situated in the neck caudal to the larynx. It produces hormones (see below) that are vital in maintaining normal growth and metabolism. It also serves as a storehouse for iodine.
Enlarge picture
Microscopic appearance of the thyroid gland. By permission from Guyton R, Hall JE, Textbook of Medical Physiology, Saunders, 2000
thyroid hormones
iodothyronines secreted by the thyroid gland, principally thyroxine (tetraiodothyronine, T4) and tri-iodothyronine (T3); derived from iodination of tyrosyl residues in thyroglobulin. The pharmaceutical names for T4 and T3 are levothyroxine and liothyronine, respectively. Regulate basal metabolic rate.
thyroid parafollicular cell
see c cell.
thyroid radioiodine uptake
used as a thyroid function test but superseded these days by estimates of T4 (thyroxine).
thyroid-stimulating hormone (TSH)
thyroid tumor
mostly follicular adenomas in old-aged dogs, cats and horses; papillary adenomas are rare.

Patient discussion about thyroid

Q. Anyone know if there is a connection between Fibromyalgia and your Thyroid gland? I have Fibromyalgia and I read that if your diagnosed with this you can have Thyroid problems also. If anyone knows out there please inform me. Many thanks.

A. Below is an interesting article on the subject. A significant percentage of the estimated 20 million people with hypothyroidism end up also being diagnosed with fibromyalgia. Some experts believe that like most cases of hypothyroidism, fibromyalgia is also autoimmune in nature. Others believe that fibromyalgia may be one manifestation of an under active metabolism – hypometabolism – and is therefore one variation on thyroid dysfunction.

Q. Is there any natural herb for a sluggish thyroid My uncle is suffering with thyroid for the past 8 months and the treatment he underwent is not successful. Is there any natural herb for a sluggish thyroid?

A. first of all the thyroid gland is situated in the front of the neck, just below the larynx(voice box)it consist of two lobes,one one each side of the trachea(windpipe)joined by a narrower portion of tissue called the isthmus---the thyroid grand produces hormones that regulate metabolism(the chemical activitie in cells that release energy from nutrients or uses energy to create other substances,such as proteins)the thyroid gland regulates the level of calcium in the body.insufficient thyroid hormones prduction is known as hypothyroidism(sluggish thyroid)symtoms include tirednes/dry skin/hair loss/weight gain/constipation/and sensitivity to cold.--because iodine is necessary for the production of thyroid hormones/calcium-ASk your DR before trying natural meds-because they ma interfere with what your uncle is taking now?--and you need to find out from your DR WHY is his thyroid sluggish--mrfoot56--peace

Q. I was told to have my thyroid test and now after the result they have told me to go for MRI I am 23 years old lady……I was told to have my thyroid test and now after the result they have told me to go for MRI……..and I know one of my friend had same type of symptoms and after thyroid test she was on her medicines and now she is well…they say it may be fibromyalgia or sclerosis …why they want me to go for MRI…..there seems to be something serious?

A. i think the MRI is to detect any signs of sclerosis. they try to get a differential diagnosis so they look for sclerosis or any other pathological sign. they didn't find anything in the Thyroid?

More discussions about thyroid
References in periodicals archive ?
Nadir gorulen bu dermatozun olusumuna neden olan tetikleyici faktor tam olarak bilinmemekle birlikte diyabetes mellitus, tiroid hastaliklari, hipertansiyon, atopi, artrit, irritabl kolon, ulseratif kolit, endometriyozis, hepatit B ve C virusu enfeksiyonu, yaygin sarkoptes skabiei infestasyonu, edinsel immun yetmezlik sendromu, sifiliz, cesitli medikasyonlar ve malignitelerle iliskili olarak gorulebilecegi bildirilmistir (3,7,9).
Kan numunelerinden Hs-CRP NT ProBNP sedimantasyon, lokosit sayisi, tiroid hormonlari ve fibrinojen seviyeleri olculdu.
Tiroid ultrasonografisinde; tiroid bezinde parankimde hipoekojenite ve heterojen yapi saptanip, tiroid boyutlarinda artma goruldu, istenen endokrin konsultasyonu sonucunda "otoimmun tiroidit" tanisi konuldu.
Laboratuvar incelemelerinde; aclik kan glukozu, beibrek fonksiyonlari, karaciger fonksiyon testleri, tiroid fonksiyon testleri, estradiol (E2), prolaktin, progesteron, kortizol, DHEAS, buyume hormonu ve ACTH, degerleri normal sinirlardaydi.
Yapilan hemogram, biyokimya ve tiroid fonksiyon testleri normal olarak tespit edildi.
Transfuzyon oncesi alinan kanlarindan hemoglobin, aclik kan sekeri, ferritin, alanin aminotransferaz, aspartat aminotransferaz, kalsiyum, fosfor, alkalen fosfataz, tiroid stimulan hormon, serbest tiroksin, intakt paratiroid hormon degerlerine bakildi.
Laboratuvar incelemesinde, idrar tetkikleri, serum elektrolitleri, karaciger, bobrek, tiroid ve paratiroid fonksiyonlari ile ilgili biyokimyasal testleri normal sinirlar icinde bulundu.
Tiroid kanseri, melanoma, osteosarkoma, meninjiom, yumusak doku sarkomlari ve hematolojik maliniteler WS ile birlikteligi en sik rapor edilen maliniteler arasinda yer almaktadir (1), (9).
3 P53 1 61 K + (M, S) 2 54 E + (M) %2-8 3 64 E + (M) - 4 67 K + (M) 5 58 E + (M) - 6 60 E + (M) 7 50 E + (M) 8 55 E + (M) 9 55 E + (M) 10 56 E + (M) - 11 40 K + (M) 12 61 E + (M) - 13 77 E + (M) %20 14 80 E + (M) 15 68 E + (M) 16 80 K + (M) 17 75 K + (S) + % 10-20 18 53 E + (M) 19 69 K + (M) 20 75 E + (M) 21 60 E + (M) - 22 65 E + - %50 (M,S) 23 80 K + (M) - 24 78 K + (M) 25 60 E + (M) E: Erkek, K: Kadin, Z: zaylf boyanma, M: Membranoz boyanma, S: Sitoplazmik boyanma, EMA; Epitelyal membranoz antijen, TTF-i: Tiroid transkripsiyon faktor 1 (Kalretin degerlendirmesinde nukleer boyanma pozitif kabul edilmistir) Grafik 1.