thyroid (redirected from thyroid C cell)

thyroid /thy·roid/ (thi´roid)

1. the thyroid gland; see under gland.

2. pertaining to the thyroid gland.

3. scutiform.

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.

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thy·roid (throid)

n.

1. The thyroid gland.

2. The thyroid cartilage.

3. A powdered preparation of the thyroid gland of certain domestic animals, used in the treatment of cretinism and myxedema, in certain cases of obesity, and in skin disorders.

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thyroid adj.

thy·roidal adj.

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Thyroid

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

Mentioned in: Exophthalmos, Gynecomastia, Hypothermia

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thyroid.

See thyroid gland.

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thyroid

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.

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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

see hypothyroidism, hyperthyroidism.

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.

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)

see thyrotropin.

thyroid tumor

mostly follicular adenomas in old-aged dogs, cats and horses; papillary adenomas are rare.

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thyroid, desiccated

Armour Thyroid, Thyrar, Thyroid Strong, Westhroid

Pharmacologic class: Hormone supplement

Therapeutic class: Thyroid hormone

Pregnancy risk category A

FDA Boxed Warning

• Drug shouldn't be used alone or with other agents to treat obesity or weight loss. In euthyroid patients, doses within range of daily hormonal requirements are ineffective for weight loss. Larger doses may cause serious or life-threatening toxicity, particularly when given with sympathomimetic amines (such as those used for anorectic effects).

Action

Regulates cell growth and differentiation and increases metabolic rate of body tissues; effects mediated at cellular level

Availability

Tablets: 15 mg, 30 mg, 60 mg, 90 mg, 120 mg, 180 mg, 240 mg, 300 mg

⊘Indications and dosages

➣ Mild hypothyroidism

Adults: Initially, 60 mg/day P.O.; may increase by 60 mg q 30 days to desired response. Usual maintenance dosage is 60 to 180 mg/day.

➣ Severe hypothyroidism

Adults: Initially, 15 mg/day P.O. daily; may increase to 30 mg/day after 2 weeks and then to 60 mg/day 2 weeks later. Assess after 1 month, and again 1 month later at 60 mg-dose. If necessary, dosage may then increase to 120 mg/day P.O. for 2 months, with assessment repeated. Subsequent assessments and dosage increases may occur up to a maximum of 180 mg/day.

➣ Congenital or severe hypothyroidism

Children: Initially, 15 mg P.O. daily; may increase to 30 mg/day after 2 weeks, with subsequent increases at 2-week intervals. Maintenance dosage may be higher in growing children than in hypothyroid adults.

Dosage adjustment

• Cardiovascular disease
• Elderly patients

Contraindications

• Hypersensitivity to drug or its components
• Adrenal insufficiency
• Thyrotoxicosis

Precautions

Use cautiously in:
• tartrazine sensitivity (some products)
• cardiovascular disease
• elderly patients
• breastfeeding patients.

Administration

• Give before breakfast each day.

Route	Onset	Peak	Duration
P.O.	Unknown	12-48 hr	Unknown

Adverse reactions

CNS: insomnia, tremors, headache

CV: palpitations, angina pectoris, hypertension, tachycardia, arrhythmias, cardiac arrest

GI: nausea, vomiting, diarrhea

GU: menstrual irregularities

Metabolic: heat intolerance, thyroid storm

Musculoskeletal: accelerated bone maturation (in children)

Skin: sweating

Other: weight loss, appetite changes, fever

Interactions

Drug-drug. Anticoagulants, catecholamines, sympathomimetics: increased effects of these drugs

Bile acid sequestrants: decreased thyroid hormone absorption

Digoxin, insulin, oral hypoglycemics: decreased effects of these drugs

Estrogen: decreased thyroid hormone effects

Oral anticoagulants: increased risk of bleeding

Drug-diagnostic tests. Aspartate aminotransferase, creatine kinase, glucose, lactate dehydrogenase, protein-bound iodine: increased levels

Thyroid function tests: decreased values

Drug-herbs. Bugleweed, soy: increased adverse drug reactions

Patient monitoring

☞ Monitor for chest pain. If it occurs, withhold drug and contact prescriber.
• Assess vital signs and temperature frequently.
☞ Monitor thyroid function tests closely. Immediately report evidence of thyroid storm.
• In diabetic patient, monitor blood glucose level closely.
• In children, monitor sleeping pulse rate and morning basal temperature.
• In female on long-term therapy, monitor bone density tests.

Patient teaching

• Tell patient to take each morning before breakfast.
☞ Caution patient not to stop therapy abruptly. Dosage must be tapered.
☞ Advise patient to immediately report chest pain or signs and symptoms of drug toxicity (fever, chest pain, rapid pulse, skipped heartbeats, heat intolerance, excessive sweating, nervousness, emotional instability).
• Instruct patient to tell all prescribers he's taking drug. Caution him not to use over-the-counter preparations without consulting prescriber.
• Tell diabetic patient that drug may alter blood glucose level. Encourage frequent glucose self-monitoring.
• As appropriate, review all other significant and life-threatening adverse reactions and interactions, especially those related to the drugs, tests, and herbs mentioned above.

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thyroid

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

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Patient discussion about thyroid C cell.

Q. Has anyone tried natural hormones for hypo-thyroidism or fibromyalgia? I am on the low normal range for hypo-thyroidism (do not take meds for) and was diagnosed years ago with fibromyalgia. I take Ultram for the pain which also helps my fatigue factor but I still feel so sluggish sometimes and just want to sleep. I'm on an anti-depressant as it is. I've been hearing more about natural hormone therapy for these conditions and was wondering if anyone out there has tried this.

A. The Ultram and the anti-depressants do that and as for the natural hormone treatments they don't really work. The Gulf War that gave me hypo-thyroid and hypo-prolactimia which is the Pituitary Gland acting up. On top of the fibro,fatique,pain and recovering from arsenic poison I was put on hormone treatments and it made things worse. I blew up like a balloon, I was still tired and it never corrected the problem with my glands. I tried everything out there and I wasn't getting any better until now. A friend of mine told me of this product called Vitalitea and that it could help me.I was desperate to get my health back and boy did I. Go to Ai3global.com/greentea and click on product and wellness and read it. Check out the www on the healing properties of quality green tea and not the stuff you by at the local store. My fatique, and chronic pain is gone. My Fibromyalgia is so, so mild. I do fun things again after 7 year of suffering. You won't regret it. It is all natural.

Q. What Are the Symptoms of Hypothyroidism? My friend suffers from hypothyroidism. I have been feeling tired lately and she told me I should get examined too. What are the symptoms of this disease?

A. Hypothyroidism is a situation that can mimic a number of other medical conditions. Therefore, the diagnosis of hypothyroidism is often missed. Among the common symptoms are fatigue (especially due to poor muscle tone), Cold intoleranc(increased sensitivity to cold), constipation, weight gain, dry skin, slow heart rate and more. This can be easily treated with hormonal replacement after proper medical consultation.

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.
http://thyroid.about.com/cs/fibromyalgiacfs/a/fibrothyroid.htm