hyperthyroidism

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Hyperthyroidism

 

Definition

Hyperthyroidism is the overproduction of thyroid hormones by an overactive thyroid.

Description

Located in the front of the neck, the thyroid gland produces the hormones thyroxine (T4) and triiodothyronine (T3) that regulate the body's metabolic rate by helping to form protein ribonucleic acid (RNA) and increasing oxygen absorption in every cell. In turn, the production of these hormones are controlled by thyroid-stimulating hormone (TSH) that is produced by the pituitary gland. When production of the thyroid hormones increases despite the level of TSH being produced, hyperthyroidism occurs. The excessive amount of thyroid hormones in the blood increases the body's metabolism, creating both mental and physical symptoms.
The term hyperthyroidism covers any disease which results in overabundance of thyroid hormone. Other names for hyperthyroidism, or specific diseases within the category, include Graves' disease, diffuse toxic goiter, Basedow's disease, Parry's disease, and thyrotoxicosis. The disease is 10 times more common in women than in men, and the annual incidence of hyperthyroidism in the United States is about one per 1,000 women. Although it occurs at all ages, hyperthyroidism is most likely to occur after the age of 15. There is a form of hyperthyroidism called Neonatal Grave's disease, which occurs in infants born of mothers with Graves' disease. Occult hyperthyroidism may occur in patients over 65 and is characterized by a distinct lack of typical symptoms. Diffuse toxic goiter occurs in as many as 80% of patients with hyperthyroidism.

Causes and symptoms

Hyperthyroidism is often associated with the body's production of autoantibodies in the blood which cause the thyroid to grow and secrete excess thyroid hormone. This condition, as well as other forms of hyperthyroidism, may be inherited. Regardless of the cause, hyperthyroidism produces the same symptoms, including weight loss with increased appetite, shortness of breath and fatigue, intolerance to heat, heart palpitations, increased frequency of bowel movements, weak muscles, tremors, anxiety, and difficulty sleeping. Women may also notice decreased menstrual flow and irregular menstrual cycles.
Patients with Graves' disease often have a goiter (visible enlargement of the thyroid gland), although as many as 10% do not. These patients may also have bulging eyes. Thyroid storm, a serious form of hyperthyroidism, may show up as sudden and acute symptoms, some of which mimic typical hyperthyroidism, as well as the addition of fever, substantial weakness, extreme restlessness, confusion, emotional swings or psychosis, and perhaps even coma.

Diagnosis

Physicians will look for physical signs and symptoms indicated by patient history. On inspection, the physician may note symptoms such as a goiter or eye bulging. Other symptoms or family history may be clues to a diagnosis of hyperthyroidism. An elevated body temperature (basal body temperature) above 98.6 °F (37 °C) may be an indication of a heightened metabolic rate (basal metabolic rate) and hyperthyroidism. A simple blood test can be performed to determine the amount of thyroid hormone in the patient's blood. The diagnosis is usually straightforward with this combination of clinical history, physical examination, and routine blood hormone tests. Radioimmunoassay, or a test to show concentrations of thyroid hormones with the use of a radioisotope mixed with fluid samples, helps confirm the diagnosis. A thyroid scan is a nuclear medicine procedure involving injection of a radioisotope dye which will tag the thyroid and help produce a clear image of inflammation or involvement of the entire thyroid. Other tests can determine thyroid function and thyroid-stimulating hormone levels. Ultrasonography, computed tomography scans (CT scan), and magnetic resonance imaging (MRI) may provide visual confirmation of a diagnosis or help to determine the extent of involvement.

Treatment

Treatment will depend on the specific disease and individual circumstances such as age, severity of disease, and other conditions affecting a patient's health.

Antithyroid drugs

Antithyroid drugs are often administered to help the patient's body cease overproduction of thyroid hormones. This medication may work for young adults, pregnant women, and others. Women who are pregnant should be treated with the lowest dose required to maintain thyroid function in order to minimize the risk of hypothyroidism in the infant.

Radioactive iodine

Radioactive iodine is often prescribed to damage cells that make thyroid hormone. The cells need iodine to make the hormone, so they will absorb any iodine found in the body. The patient may take an iodine capsule daily for several weeks, resulting in the eventual shrinkage of the thyroid in size, reduced hormone production and a return to normal blood levels. Some patients may receive a single larger oral dose of radioactive iodine to treat the disease more quickly. This should only be done for patients who are not of reproductive age or are not planning to have children, since a large amount can concentrate in the reproductive organs (gonads).

Surgery

Some patients may undergo surgery to treat hyperthyroidism. Most commonly, patients treated with thyroidectomy, in the form of partial or total removal of the thyroid, suffer from large goiter and have suffered relapses, even after repeated attempts to address the disease through drug therapy. Some patients may be candidates for surgery because they were not good candidates for iodine therapy, or refused iodine administration. Patients receiving thyroidectomy or iodine therapy must be carefully monitored for years to watch for signs of hypothyroidism, or insufficient production of thyroid hormones, which can occur as a complication of thyroid production suppression.

Alternative treatment

Consumption of foods such as broccoli, brussel sprouts, cabbage, cauliflower, kale, rutabagas, spinach, turnips, peaches, and pears can help naturally suppress thyroid hormone production. Caffeinated drinks and dairy products should be avoided. Under the supervision of a trained physician, high dosages of certain vitamin/mineral combinations can help alleviate hyperthyroidism.

Prognosis

Hyperthyroidism is generally treatable and carries a good prognosis. Most patients lead normal lives with proper treatment. Thyroid storm, however, can be life-threatening and can lead to heart, liver, or kidney failure.

Prevention

There are no known prevention methods for hyperthyroidism, since its causes are either inherited or not completely understood. The best prevention tactic is knowledge of family history and close attention to symptoms and signs of the disease. Careful attention to prescribed therapy can prevent complications of the disease.

Resources

Organizations

Thyroid Foundation of America. 350 Ruth Sleeper Hall-RSL 350, Parkman St., Boston, MA. 02114. (800) 832-8321. 〈http://www.clark.net/pub/tfa〉.

Other

"Endocrine Disorder and Endocrine Surgery." Endocrine Web Page. http://www.endocrineweb.com.

Key terms

Goiter — Chronic enlargement of the thyroid gland.
Gonads — Organs that produce sex cells—the ovaries and testes.
Palpitations — Rapid and forceful heartbeat.
Radioisotope — A chemical tagged with radioactive compounds that is injected during a nuclear medicine procedure to highlight organ or tissue.
Thyroidectomy — Removal of the thyroid gland.

hyperthyroidism

 [hi″per-thi´roi-dizm]
excessive functional activity of the thyroid gland; see also thyrotoxicosis. It affects women far more frequently than men, with peak incidence between 30 and 50 years of age, and is commonly part of Graves' disease, a syndrome that may include goiter and exophthalmos. It is also seen in association with thyroiditis, thyroid cancer, molar pregnancy, hyperemesis gravidarum, and toxic multinodular goiter. Several different physiologic mechanisms may cause increased hyperthyroidism: increased synthesis and secretion of thyroid hormones, excessive release of the hormones, or ingestion of excessive amounts of the hormones. adj., adj hyperthy´roid.
Symptoms. Manifestations vary from mild symptoms of weakness, insomnia, weight loss, and tremulousness to extreme tachycardia, palpitations, exertional dyspnea, and ankle edema. The hyperthyroid patient's metabolic rate is greatly accelerated, speeding up bodily processes. Severity of symptoms is related to patient age, length of illness, and level of excess thyroid hormone in circulation.

The best screening test for hyperthyroidism is the thyroid-stimulating hormone (TSH) test (or assay). Other laboratory tests that may be performed include assessments of free triiodothyronine and free thyroxine, the triiodothyronine resin uptake test, and radioimmunoassay for triiodothyronine. Selected cases, such as hyperthyroidism during pregnancy, may warrant evaluation of thyroid antibodies. A radioactive iodine uptake test or thyroid scan may also be useful evaluations.
Treatment. General measures of support for the patient suffering from hyperthyroidism include physical and emotional rest and a high caloric, nutritional diet supplemented with vitamins and calcium. The choice of additional medications and/or surgical intervention will depend on the age of the patient, the cause of the hyperthyroidism, and the patient's response to selected therapies.
Radioactive iodine (radioiodine) is usually the drug of choice; either 125I or 131I may be used. Clinical Guidelines have been developed by the American Association of Clinical Endocrinologists and the American College of Endocrinology. They note that some clinicians are hesitant to use radioactive iodine in treatment of any woman of childbearing age, but there is no evidence to back up such fears. However, treatment with radioactive iodine is contraindicated during pregnancy and on the nursing mother, and a waiting period of six months is advised after the end of treatment before initiation of pregnancy. Some patients may require treatment with antithyroid drugs before radioactive iodine. Careful monitoring of the patient is required as thyroid function diminishes. Many patients experience hypothyroidism following treatment; it may occur immediately or may be delayed until a considerable time later.

The dosage depends on the size of the gland and its sensitivity to radiation. The radioactive iodine is administered orally, usually in one small dose. Some individuals receiving these small doses may require two or even three doses. Radioactive iodine takes several months to achieve the desired effect, and symptoms usually improve after about four weeks. Antithyroid medication and beta-blockers may be necessary to control the symptoms associated with hyperthyroidism during this initial time period. All patients receiving radioactive iodine must be observed for signs of thyroid crisis resulting from radiation-induced thyroiditis.
Antithyroid Drugs. The antithyroid drugs, especially propylthiouracil, are prescribed in pregnancy and in cases where remission of the disease is a goal. The prime candidates for this therapy are patients with small goiters and mild symptoms. It is important that the patient take the medication in the prescribed time and strictly according to schedule. Propylthiouracil produces agranulocytosis, which can develop quickly. For this reason patients receiving this drug must be instructed to report to the physician any sore throat, fever, or rash, so that white blood cell counts can be done and the patient's condition evaluated.

Iodine preparations often are given routinely for 10 to 14 days prior to surgery to reduce the vascularity of the thyroid. Another important use of antithyroid drugs is in treatment of thyroid crisis. Iodine preparations such as a saturated solution of potasssium iodide have only a temporary effect.
Surgery. Subtotal thyroidectomy is now rarely done as a treatment for hyperthyroidism. It is reserved for special circumstances, such as a pregnant woman who cannot tolerate antithyroid medications or a patient with a large, nodular goiter. It may also be done on a patient who refuses treatment with radioactive iodine.
Patient Care. Patients with hyperthyroidism are subject to a variety of complex and long-term problems of physical and mental health. Among the nursing diagnoses commonly seen in these patients are agitation and irritability related to increased metabolic rate; anxiety and psychologic stress related to frequent diagnostic testing and its outcomes and to ongoing treatments; nutritional imbalance: less than body requirements, related to elevated metabolic rate; alteration in comfort related to heat intolerance and diaphoresis; potential for injury related to thyroid crisis; and disturbance in self-concept related to uncontrollable emotional outbursts, weight loss, and chronic nature of the illness.

Because of the increased irritability, it is helpful to keep environmental stimuli at a minimum. Patients should be approached in a calm and unhurried manner and their wishes regarding visitors during hospitalization respected. To assure as much rest and sleep as possible, meals and treatments are scheduled so that the patient has periods of uninterrupted rest. When at home or work, the patient is encouraged to take time for rest. Physical and mental rest are important because stress can act as a stimulus to and cause increased activity of the thyroid.

Information about tests and prescribed treatments should be provided to the patient and family. Caloric intake is increased to a daily intake of 3000 calories, and may require supplemental feeding to maintain desired body weight. Consultation with a dietitian can help improve the patient's understanding of and compliance with the prescribed diet. Patients and their families need to understand the nature of the illness, its effect on emotions, and the importance of complying with the regimen of care. They should report regularly to professional caregivers for support and guidance.

hy·per·thy·roid·ism

(hī-per-thī'royd-izm),
An abnormality of the thyroid gland in which secretion of thyroid hormone is usually increased and no longer under regulatory control of hypothalamic-pituitary centers; characterized by a hypermetabolic state, usually with weight loss, tremulousness, elevated plasma levels of thyroxin and/or triiodothyronine, and sometimes exophthalmos; may progress to severe weakness, wasting, hyperpyrexia, and other manifestations of thyroid storm; often associated with Graves disease.
See also: thyrotoxicosis.

hyperthyroidism

/hy·per·thy·roid·ism/ (-thi´roid-izm) excessive thyroid gland activity, marked by increased metabolic rate, goiter, and disturbances in the autonomic nervous system and in creatine metabolism.hyperthy´roid

hyperthyroidism

(hī′pər-thī′roi-dĭz′əm)
n.
1. Excessive production of thyroid hormones.
2. Excessive activity of the thyroid gland, characterized by increased basal metabolism.

hyperthyroidism

[-thī′roidiz′əm]
Etymology: Gk, hyper + thyreos, shield, eidos, form
a condition characterized by hyperactivity of the thyroid gland. The gland is usually enlarged, secreting greater than normal amounts of thyroid hormones, and the metabolic processes of the body are accelerated. Nervousness, exophthalmos, tremor, constant hunger, weight loss, fatigue, heat intolerance, palpitations, and diarrhea may develop. Antithyroid drugs, such as propylthiouracil or methimazole, are usually prescribed. Radioactive iodine may be prescribed in certain cases. Surgical ablation of the gland is sometimes necessary. Untreated hyperthyroidism may lead to death from cardiac failure. See also Graves' disease, thyroid storm.

hyperthyroidism

Thyroid excess Endocrinology A state characterized by excess thyroid activity, due to ↑ secretion of thyroid hormones and ↓ response of hypothalamic–long and pituitary–short feedback loops Etiology Graves' disease, iatrogenic, toxic nodular goiter, thyroiditis, neonatal hyperthyroidism, exogenous iodide, factitious illness, malignancy struma ovarii Clinical ↑ O2 consumption, ↑ basal metabolic rate, exophthalmos, nervousness, asthenia, weight loss Lab ↑ T3 and/or T4 Management Antithyroid drugs–methimazole, carbimazole, propylthiouracil, radioiodine, surgery. See Apathetic hyperthyroiditis, Factitious hyperthyroiditis, Subclinical hyperthyroiditis, Thyroid storm. Cf Hypothyroidism.

hy·per·thy·roid·ism

(hī'pĕr-thī'royd-izm)
An abnormality of the thyroid gland in which secretion of thyroid hormone is usually increased and is no longer under regulatory control of hypothalamic-pituitary centers; characterized by a hypermetabolic state, usually with weight loss, tremulousness, elevated plasma levels of thyroxin and/or triiodothyronine; often associated with exophthalmos (as found in Graves disease).

hyperthyroidism

Overactivity of the thyroid gland. See THYROTOXICOSIS.

hyperthyroidism

a medical condition in which overproduction of the thyroid hormone causes nervousness, sensitivity to heat and insomnia.

hyperthyroidism

; thyrotoxicosis high blood levels of thyroxine due to intrinsic thyroid disease (e.g. autoimmune or inflammatory disease; benign thyroid tumour); more common in women than men (5:1 ratio); characterized by irritability, hyperkinesis and tremor, warm vasodilated extremities with palmar and plantar erythema, exophthalmos and lid lag, goitre, pretibial myxoedema, onycholysis, proximal myopathy, weight loss, atrial fibrillation and tachycardia; treated by thyroid radioablation, antithyroid drugs (e.g. carbimazole) and/or thyroidectomy

hyperthyroidism,

n the overproduction of triiodothyronine and/or tetraiodothyronine by the thyroid gland. Symptoms include sweating, weakness, nervousness, loss of weight, frequent and loose defecation, increased sensitivity to heat, fatigue, and irritability. Graves' disease, an autoimmune disorder, is the most common cause of hyperthyroidism.

ophthalmopathy, thyroid 

Disease of the thyroid gland which leads to ocular manifestations. There are two main types: mild and severe. The mild type occurs in Graves' disease in which most or some of the typical signs may be present and to a different extent (e.g. retraction of the eyelids, exophthalmos, defective eye movements and optic neuropathy). The severe type is much less common and affects the sexes equally in middle age. All the signs of Graves' disease are present but are more pronounced with the addition of oedema of the eyelids and of the conjunctiva, conjunctival injection, enlargement of the extraocular muscles and in a few cases there is also optic neuropathy due to compression of the optic nerve or its blood supply with consequent visual loss, colour vision impairment and often diplopia. Syn. dysthyroid eye disease; thyroid eye disease. See accommodative insufficiency; superior limbic keratoconjunctivitis; optic neuropathy.

hy·per·thy·roid·ism

(hī'pĕr-thī'royd-izm)
An abnormality of the thyroid gland in which secretion of thyroid hormone is usually increased and no longer under regulatory control of hypothalamic-pituitary centers; characterized by a hypermetabolic state, usually with weight loss, tremulousness, elevated plasma levels of thyroxin and/or triiodothyronine, and sometimes exophthalmos.

hyperthyroidism (hī´pərthī´roid-iz´əm),

n (Parry's disease), a condition with abnormalities of calorigenic mechanisms, body tissues, blood, and body fluids and of the circulatory, muscular, and nervous systems resulting from an excessive elaboration of thyroid hormone. Manifestations include increased sweating, increased appetite, intolerance to heat, weight loss, increased protein-bound iodine (PBI), early shedding of primary teeth and early eruption of permanent teeth, tachycardia, palpitation, tremors, nervousness, muscular weakness, diarrhea, increased excretion of calcium and phosphorus, hypocholesterolemia, creatinuria, and osteoporosis. May occur as the result of primary hyperplasia, hyperfunctioning nodular goiters, functional benign tumor, or adenoma of the thyroid gland. See also goiter, exophthalmic.

hyperthyroidism

excessive functional activity of the thyroid gland. Rare in animals except in aged dogs and cats where it is associated with functional thyroid neoplasms.
Affected animals show increased thirst, weight loss despite an increased appetite, restlessness and cardiac arrhythmias.

apathetic hyperthyroidism
a small percentage of hyperthyroidic cats show lethargy, depression and anorexia; may be due to associated dysfunction.

Patient discussion about hyperthyroidism

Q. I had my blood test as I was feeling dizzy and my heart rate was raised & I was diagnosed with hyperthyroidism I had my blood test as I was feeling dizzy and my heart rate was raised & I was diagnosed with hyperthyroidism. It had just started when I was taking herbs for depression and anxiety. I am not taking herbs now and still feeling dizzy. Has anyone had any problem with Chinese herbs?

A. My mom had hyperthyroidism, but not with herbs. Until she told the exact things to the doctor, her treatment was difficult and once she revealed the medicine history to the doctor she was very well treated. Similarly I expect from you to tell your doctor about the herbs you are taking and you must tell this to your Chinese medicine practitioner as well. There are chances that you may have high level of thyroid and these herbs just boosted them or increased them as Chinese medicine do not have high side effects. Please open to your doctor during investigation and treatment.

More discussions about hyperthyroidism
References in periodicals archive ?
Initially a rare disease, feline hyperthyroidism has mushroomed to epidemic proportions in some regions of the United States, according to Leslie Bullock, a veterinarian studying the disease at Tufts University in Boston.
Feline hyperthyroidism is a disorder that occurs when the feline thyroid gland produces an excess of thyroid hormone.
While these findings are not evidence that PBDEs cause feline hyperthyroidism, they indicate a potential link that cat owners should keep in mind.

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