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Hyperthyroidism
Classification and external resources
Triiodothyronine (T3, pictured) and thyroxine (T4) are both forms of thyroid hormone. Triiodothyronine, C15[[hydrogen H12]] I3[[nitrogen N]] O4, also known as T3, is a Thyroid Thyroxine, or 353'5'-tetra­iodothyronine (often abbreviated as T4) a form of Thyroid hormones is the major Hormone secreted by the The thyroid hormones, Thyroxine ( T4) and Triiodothyronine ( T3) are Tyrosine -based Hormones produced
ICD-10 E05.
ICD-9 242.9
DiseasesDB 6348
MedlinePlus 000356
eMedicine med/1109 
MeSH D006980

Hyperthyroidism is the term for overactive tissue within the thyroid gland, resulting in overproduction and thus an excess of circulating free thyroid hormones: thyroxine (T4), triiodothyronine (T3), or both. The International Statistical Classification of Diseases and Related Health Problems (most commonly known by the abbreviation ICD) provides codes to classify Diseases The International Statistical Classification of Diseases and Related Health Problems 10th Revision ( ICD -10) is a coding of diseases and signs symptoms abnormal findings E00-E35 - Endocrine diseases (E00-E07 Thyroid gland / Thyroid hormone ( Congenital iodine-deficiency syndrome ( The International Statistical Classification of Diseases and Related Health Problems (most commonly known by the abbreviation ICD) provides codes to classify Diseases The following is a list of codes for International Statistical Classification of Diseases and Related Health Problems. The Diseases Database is a free Website that provides information about the relationships between medical conditions Symptoms, and Medications. MedlinePlus, with the MedlinePlus Medical Encyclopedia, is a website network containing Health information from the world's largest medical Library eMedicine is an online clinical medical knowledge base that was founded in 1996 by Scott Plantz and Richard Lavely two medical doctors Medical Subject Headings ( MeSH) is a huge Controlled vocabulary (or metadata system for the purpose of indexing journal articles and books The thyroid is one of the largest Endocrine glands in the body Thyroxine, or 353'5'-tetra­iodothyronine (often abbreviated as T4) a form of Thyroid hormones is the major Hormone secreted by the Triiodothyronine, C15[[hydrogen H12]] I3[[nitrogen N]] O4, also known as T3, is a Thyroid The term is also often used more loosely to describe any syndrome of excess thyroid hormone (more properly termed hyperthyroxinemia), regardless of the source. Thyrotoxicosis is the term for symptomatic hyperthyroxinemia. Hyperthyroidism is the term for overactive tissue within the Thyroid gland resulting in overproduction and thus an excess of circulating free thyroid hormones Thyroxine Thyroid hormone is important at a cellular level, affecting nearly every type of tissue in the body. It functions as a stimulus to metabolism, and is critical to normal function of the cell. In excess it overstimulates, causing "speeding up" of various body systems, and thus symptoms: Fast heart beat results in palpitations, a fast nervous system in tremor and anxiety symptoms, a fast digestive system in weight loss and diarrhea. A palpitation (medical term ectopic heart beat) is an abnormal awareness of the beating of the Heart, whether it is too slow too fast irregular Tremor is an unintentional somewhat rhythmic muscle movement involving to-and-from movements (oscillations of one or more parts of the body Anxiety is a physiological and psychological state characterized by Cognitive, Somatic, Emotional and Behavioral components In Medicine, diarrhea, also spelled diarrhoea (see spelling differences) is frequent loose or liquid Bowel movements Acute diarrhea Lack of functioning thyroid tissue results in a symptomatic lack of thyroid hormone, termed hypothyroidism. Hypothyroidism is the disease state in humans and animals caused by insufficient production of Thyroid hormone by the Thyroid gland.

Contents

Causes

Functional thyroid tissue producing an excess of thyroid hormone occurs in a number of clinical conditions. The major causes in humans are:

High blood levels of thyroid hormones (most accurately termed hyperthyroxinemia) can occur for a number of other reasons:

Inflammation of the thyroid is called thyroiditis. Graves' disease is a Thyroid disorder characterized by goiter, Exophthalmos, "orange-peel" skin and Hyperthyroidism. A Hürthle cell (also known incorrectly as Askanazy cell. Askanazy cells are interfollicular C-cells is an oncocytic cell in the thyroid that is often associated Toxic multinodular goitre (also known as toxic nodular goitre, toxic nodular struma) is a form of Hyperthyroidism - where there is excess production of Inflammation ( Latin, inflamatio, to set on fire is the complex biological response of vascular tissues to harmful stimuli such as Pathogens Thyroiditis is the inflammation of the thyroid gland The thyroid gland is located on the front of the neck below the Laryngeal prominence, and makes hormones that There are a number of different kinds of thyroiditis including Hashimoto's (immune mediated), subacute (inflammatory), and DeQuervain's (granulomatous). These may be initially associated with secretion of excess thyroid hormone, but often progress to gland dysfunction and thus, an eventual hormone deficiency.

Struma ovarii (a teratoma of the ovary) can produce excess thyroid hormone. A teratoma is a type of neoplasm. The word teratoma comes from Greek and means roughly "monstrous tumor" A teratoma is a type of neoplasm. The word teratoma comes from Greek and means roughly "monstrous tumor"

Consumption of excess thyroid hormone tablets is possible, as is the now rare event of consumption of ground beef contaminated with thyroid tissue, and thus thyroid hormone (termed "hamburger hyperthyroidism").

Amiodarone, a heart medication, can sometimes cause hyperthyroidism by a variety of different mechanisms. Amiodarone is an Antiarrhythmic agent (medication used for irregular heart beat used for various types of tachyarrhythmias (fast forms of irregular heart beat both ventricular

Postpartum thyroiditis occurs in about 7% of women during the year after they give birth. Postpartum thyroiditis is usually a transient phenomenon observed following Pregnancy and may involve Hyperthyroidism, Hypothyroidism or the two sequentially PPT typically has several phases, the first of which is hyperthyroidism. Many times, the hyperthyroidism corrects itself within weeks or months without any treatment necessary.

Signs and symptoms

Major clinical signs include weight loss (often accompanied by a ravenous appetite), anxiety, intolerance to heat, fatigue, hair loss, weakness, hyperactivity, irritability, apathy, depression, polyuria, polydipsia, and sweating. Weight loss, in the context of Medicine or Health or Physical fitness, is a reduction of the total Body weight, due to a mean loss of fluid Anxiety is a physiological and psychological state characterized by Cognitive, Somatic, Emotional and Behavioral components In Physics, heat, symbolized by Q, is Energy transferred from one body or system to another due to a difference in Temperature Major depressive disorder, also known as major depression, unipolar depression, unipolar disorder, clinical depression, or simply depression In Medicine, polyuria is a condition characterized by the passage of large volumes of urine (at least 2 Polydipsia is a medical symptom in which the patient drinks abnormally large amounts of Fluids The word derives from the Greek πολυδιψία, the Additionally, patients may present with a variety of symptoms such as palpitations and arrhythmias (notably atrial fibrillation), shortness of breath (dyspnea), loss of libido, nausea, vomiting, osteoporosis and diarrhea. A palpitation (medical term ectopic heart beat) is an abnormal awareness of the beating of the Heart, whether it is too slow too fast irregular Dysrhythmia redirects here For the American band see Dysrhythmia (band. Atrial fibrillation ( AF or afib) is a Cardiac arrhythmia (abnormal heart rhythm that involves the two upper chambers ( atria) of the Heart Dyspnea or dyspnoea (pronounced disp-nee-ah, IPA /dɪsp'niə/ from Latin dyspnoea, from Greek dyspnoia from Libido in its common usage means Sexual desire however more technical definitions such as those found in the work of Carl Jung, are more general referring to libido Nausea ( Latin: Nausea, Greek:, " Sea-sickness " also called wamble) is the sensation of unease and discomfort Vomiting (also called throwing up, emesis) is the forceful expulsion of the contents of one's Stomach through the Mouth and sometimes the In Medicine, diarrhea, also spelled diarrhoea (see spelling differences) is frequent loose or liquid Bowel movements Acute diarrhea In the elderly, these classical symptoms may not be present and they may present only with fatigue and weight loss leading to apathetic hyperthyroidism. Thyrotoxic crisis comes when the sick person is having stress. Its symptoms are increase of body temperature to over 40 degrees Celsius, tachycardia, arrhythmia, vomiting, diarrhea, dehydration, icterus, coma and death.

Neurological manifestations are tremor, chorea, myopathy, and periodic paralysis. Tremor is an unintentional somewhat rhythmic muscle movement involving to-and-from movements (oscillations of one or more parts of the body Chorea sancti viti (Latin for " St Vitus' dance " is an abnormal involuntary movement disorder one of a group of neurological disorders called Dyskinesias In Medicine, a myopathy is a neuromuscular Disease in which the Muscle fibers do not function for any one of many reasons resulting in Muscular weakness Periodic paralysis is a group of rare genetic diseases that lead to weakness or paralysis (rarely death from common triggers such as cold heat high Carbohydrate meals not Stroke of cardioembolic origin due to coexisting atrial fibrillation may be mentioned as one of the most serious complications of hyperthyroidism. A stroke is the rapidly developing loss of brain functions due to a disturbance in the blood vessels supplying blood to the brain Atrial fibrillation ( AF or afib) is a Cardiac arrhythmia (abnormal heart rhythm that involves the two upper chambers ( atria) of the Heart

As to other autoimmune disorders related with thyrotoxicosis, an association between thyroid disease and myasthenia gravis has been well recognized. Myasthenia gravis (literally "serious muscle-weakness" from Greek μύς "muscle" "weakness" and Latin gravis The thyroid disease, in this condition, is often an autoimmune one and approximately 5% of patients with myasthenia gravis also have hyperthyroidism. Myasthenia gravis rarely improves after thyroid treatment and the relationship between the two entities is as yet unknown. Some very rare neurological manifestations that are reported to be dubiously associated with thyrotoxicosis are pseudotumor cerebri, amyotrophic lateral sclerosis and a Guillain-Barré-like syndrome. Idiopathic intracranial hypertension (IIH sometimes called benign intracranial hypertension (BIH or pseudotumor cerebri (PTC is a Neurological disorder Amyotrophic Lateral Sclerosis ( ALS, sometimes called Maladie de Charcot, or in the United States Lou Gehrig's Disease) is a progressive Guillain-Barré syndrome ( GBS) (in French ɡilɛ̃ baˈʁe in English ˈɡiːlæn ˈbɑreɪ /ɡiːˈæn bəˈreɪ/ etc

Minor ocular signs, which may be present in any type of hyperthyroidism, are eyelid retraction ("stare") and lid-lag. These "fear-like" eye-signs result from thyroid hormone's exacerbation of the action of norepinephrine. In hyperthyroid stare (Dalrymple sign) the eyelids are retracted upward more than normal (the normal position is at the superior corneoscleral limbus, where the "white" of the eye begins at the upper border of the iris). Dalrymple sign is widened Palpebral (eyelid opening or eyelid spasm seen in Thyrotoxicosis (as seen in Graves' disease but also other hyperthyroid In lid-lag (von Graefe's sign), when the patient tracks an object downward with their eyes, the eyelid fails to follow the downward moving iris, and the same type of upper globe exposure which is seen with lid retraction occurs, temporarily. Von Graefe's sign ( lid lag sign) is the immobility or lagging of the upper Eyelid on downward rotation of the Eye, indicating exophthalmic These signs disappear with treatment of the hyperthyroidism, or treatment by certain anti-adrenergic drugs.

Neither of these ocular signs should be confused with exophthalmos (protrusion of the eyeball) which occurs in one thyroid-related disease (Graves' disease), but which is not caused by the hyperthyroid state in that disease, and is unrelated to it. Exophthalmos is a bulging of the Eye anteriorly out of the orbit. Graves' disease is a Thyroid disorder characterized by goiter, Exophthalmos, "orange-peel" skin and Hyperthyroidism. This forward movement of the eyes is due to the inflammation in the retro-orbital fat. Exophthalmos, when present, may exacerbate hyperthyroid lid-lag and stare, however. [1]

Diagnosis

A diagnosis may be suspected on history and physical examination, and is confirmed with blood tests.

Measuring the level of thyroid-stimulating hormone (TSH) in the blood is usually all that is required. Thyroid-stimulating hormone (also known as TSH or thyrotropin) is a Peptide hormone synthesized and secreted by Thyrotrope cells in the A low TSH indicates that the pituitary gland is being inhibited by increased levels of T4 and/or T3 in the blood, and is therefore a reliable marker of hyperthyroidism. Rarely, a low TSH indicates primary failure of the pituitary, or temporary inhibition of the pituitary due to another illness (sick euthyroid syndrome) and so checking the T4 and T3 is still clinically useful.

Measuring specific antibodies, such as anti-TSH-receptor antibodies in Graves' disease, or anti-thyroid-peroxidase in Hashimoto's thyroiditis, may also contribute to the diagnosis. Antibodies (also known as immunoglobulins, abbreviated Ig) are Gamma globulin Proteins that are found in Blood or other Bodily

Thyroid scintigraphy is a useful test to distinguish between causes of hyperthyroidism, and this entity from thyroiditis. Nuclear medicine is a branch of Medicine and Medical imaging that uses the nuclear properties of matter in diagnosis and therapy

Treatment

The major and generally accepted modalities for treatment of hyperthyroidism in humans involve initial temporary use of suppressive thyrostatics medication, and possibly later use of permanent surgical or radioisotope therapy. All approaches may cause under active thyroid function (hypothyroidism) which is easily managed with levothyroxine supplementation. Levothyroxine, also known as L-thyroxine, synthetic T4, or 353'5'-tetraiodo-L-thyronine, is a synthetic form

Temporary medical therapy

Thyrostatics

Thyrostatics are drugs that inhibit the production of thyroid hormones, such as carbimazole (used in UK) and methimazole (used in US), and propylthiouracil. Carbimazole is used to treat Hyperthyroidism. Carbimazole is a Pro-drug as after absorption it is converted to the active form Methimazole. Methimazole (also known as Tapazole) is an antithyroid drug similar in action to Propylthiouracil, and part of the Thioamide Propylthiouracil ( PTU) or 6-N-Propylthiouracil (PROP is a Thioamide drug used to treat Hyperthyroidism by decreasing the amount of Thyrostatics are believed to work by inhibiting the iodination of thyroglobulin by thyroperoxidase, and thus, the formation of tetra-iodothyronine (T4). Propylthiouracil also works outside the thyroid gland, preventing conversion of (mostly inactive) T4 to the active form T3. Because thyroid tissue usually contains a substantial reserve of thyroid hormone, thyrostatics can take weeks to become effective, and the dose often needs to be carefully titrated over a period of months.

A very high dose is often needed early in treatment, but if too high a dose is used persistently, patients can develop symptoms of hypothyroidism. Hypothyroidism is the disease state in humans and animals caused by insufficient production of Thyroid hormone by the Thyroid gland.

Beta-blockers

Many of the common symptoms of hyperthyroidism such as palpitations, trembling, and anxiety are mediated by increases in beta adrenergic receptors on cell surfaces. Beta blockers are a class of drug which offset this effect, reducing rapid pulse associated with the sensation of palpitations, and decreasing tremor and anxiety. Beta blockers (sometimes written as β-blocker) are a class of drugs used for various indications but particularly for the management of Cardiac arrhythmias This doesn't help the underlying problem of excess thyroid hormone, but makes the symptoms much more manageable, particularly as definitive treatment with thryostatic drugs can take a number of months to work. Propranolol in the UK, and Metoprolol in the US, are most frequently used to augment treatment for hyperthyroid patients. Propranolol ( INN) is a non-selective Beta blocker mainly used in the treatment of Hypertension. Metoprolol is a selective β1 receptor blocker used in treatment of several diseases of thecardiovascular system especially Hypertension.

Permanent treatments

Surgery as an option predates the use of the less invasive radioisotope therapy, but is still required in cases where the thyroid gland is enlarged and causing compression to the neck structures, or the underlying cause of the hyperthyroidism may be cancerous in origin.

Surgery

Surgery (to remove the whole thyroid or a part of it) is not extensively used because most common forms of hyperthyroidism are quite effectively treated by the radioactive iodine method. Surgery (from the χειρουργική cheirourgikē, via chirurgiae meaning "hand work" is a medical specialty that uses operative manual and instrumental However, some Graves' disease patients who cannot tolerate medicines for one reason or another, patients who are allergic to iodine, or patients who refuse radioiodine opt for surgical intervention. Also, some surgeons believe that radioiodine treatment is unsafe in patients with unusually large gland, or those whose eyes have begun to bulge from their sockets, claiming that the massive dose of iodine needed will only exacerbate the patient's symptoms. The procedure is quite safe - some surgeons even perform partial thyroidectomies on an out-patient basis.

Radioiodine

In Iodine-131 (Radioiodine) Radioisotope Therapy, radioactive iodine is given orally (either by pill or liquid) on a one-time basis to destroy the function of a hyperactive gland. Iodine-131 (131I, also called radioiodine, is a Radioisotope of Iodine which has medical and pharmaceutical uses Radiation therapy (or radiotherapy) is the medical use of Ionizing radiation as part of Cancer treatment to control Malignant Patients who do not respond to the first dose are sometimes given an additional radioactive iodine treatment in a larger dose. The iodine given for ablative treatment is different from the iodine used in a scan. Radioactive iodine is given after a routine iodine scan, and uptake of the iodine is determined to confirm hyperthyroidism. The radioactive iodine is picked up by the active cells in the thyroid and destroys them. Since iodine is only picked up by thyroid cells (and picked up more readily by over-active thyroid cells), the destruction is local, and there are no widespread side effects with this therapy. Radioactive iodine ablation has been safely used for over 50 years, and the only major reasons for not using it are pregnancy and breast-feeding.

A common outcome following radioiodine is a swing to the easily treatable hypothyroidism, and this occurs in 78% of those treated for Graves' thyrotoxicosis and in 40% of those with toxic multinodular goitre or solitary toxic adenoma. Hypothyroidism is the disease state in humans and animals caused by insufficient production of Thyroid hormone by the Thyroid gland. [2] Use of higher doses of radioiodine reduces the incidence of treatment failure, with the higher response to treatment consisting mostly of higher rates of hypothyroidism. [3] There is increased sensitivity to radioiodine therapy in thyroids appearing on ultrasound scans as more uniform (hypoechogenic), due to densely packed large cells, with 81% later becoming hypothyroid, compared to just 37% in those with more normal scan appearances (normoechogenic). [4]

Veterinary medicine

Cats

In veterinary medicine, hyperthyroidism is one of the most common endocrine conditions affecting older domesticated cats. The disease has become significantly more common since the first reports of feline hyperthyroidism in the 1970s. In cats, one cause of hyperthyroidism tends to be benign tumors, but the reason those cats develop such tumors continues to be researched.

However, recent research published in Environmental Science & Technology, a publication of the American Chemical Society, suggests that many cases of feline hyperthyroidism are associated with exposure to environmental contaminants called polybrominated diphenyl ethers (PBDEs), which are present in flame retardants in many household products, particularly furniture and some electronic products.

The study from which the report was based, was conducted jointly by researchers at the EPA's National Health and Environmental Effects Laboratory and Indiana University. In the study, which involved 23 pet cats with feline hyperthyroidism, PDBE blood levels were three times as high as those in younger, non-hyperthyroid cats. Ideally, PBDE and related endocrine disruptors that seriously damage health would not be present in the blood of any animals or humans.

Most recently, mutations of the thyroid stimulating hormone receptor have been discovered which cause a constitutive activation of the thyroid gland cells. Many other factors may play a role in the pathogenesis of the disease such as goitrogens (isoflavones such as genistein, daidzein and quercertin) and iodine and selenium content in the diet.

The most common presenting symptoms are: rapid weight loss, tachycardia (rapid heart rate), vomiting, diarrhea, increased consumption of fluids (polydipsia) and food, and increased urine production (polyuria). Weight loss, in the context of Medicine or Health or Physical fitness, is a reduction of the total Body weight, due to a mean loss of fluid Vomiting (also called throwing up, emesis) is the forceful expulsion of the contents of one's Stomach through the Mouth and sometimes the In Medicine, diarrhea, also spelled diarrhoea (see spelling differences) is frequent loose or liquid Bowel movements Acute diarrhea Polydipsia is a medical symptom in which the patient drinks abnormally large amounts of Fluids The word derives from the Greek πολυδιψία, the In Medicine, polyuria is a condition characterized by the passage of large volumes of urine (at least 2 Other symptoms include hyperactivity, possible aggression, heart murmurs, a gallop rhythm, an unkempt appearance, and large, thick nails. Murmurs are abnormal Heart sounds that are produced as a result of turbulent blood flow which is sufficient to produce audible noise A gallop rhythm refers to a (usually abnormal rhythm of the heart on Auscultation. About 70% of afflicted cats also have enlarged thyroid glands (goiter). A goitre ( BrE) or goiter ( AmE) ( Latin struma) also called a bronchocele, is a swelling in the neck (just below the

The same three treatments used with humans are also options in treating feline hyperthyroidism (surgery, radioiodine treatment, and anti-thyroid drugs). Drugs must be given to cats for the remainder of their lives, but may be the least expensive option, especially for very old cats. Radioiodine treatment and surgery often cure hyperthyroidism. Some veterinarians prefer radioiodine treatment over surgery because it does not carry the risks associated with anesthesia. Anesthesia, or anaesthesia (see spelling differences; from Greek grc αν- an-, "without" and grc αἲσθησις Radioiodine treatment, however, is not available in all areas for cats. The reason is that this treatment requires nuclear radiological expertise and facilities, since the animal's urine is radioactive for several days after the treatment, requiring special inpatient handling and facilities usually for a total of 3 weeks (first week in total isolation and the next two weeks in close confinement). [5] Surgery tends to be done only when just one of the thyroid glands is affected (unilateral disease); however following surgery, the remaining gland may become over-active. As in people, one of the most common complications of the surgery is hypothyroidism. Hypothyroidism is the disease state in humans and animals caused by insufficient production of Thyroid hormone by the Thyroid gland.

Dogs

Hyperthyroidism is very rare in dogs (occurring in less than 1 or 2% of dogs), who instead tend to have the opposite problem: hypothyroidism. Hypothyroidism is the disease state in humans and animals caused by insufficient production of Thyroid hormone by the Thyroid gland. When hyperthyroidism does appear in dogs, it tends to be due to over-supplementation of the thyroid hormone during treatment for hypothyroidism. Symptoms usually disappear when the dose is adjusted.

Occasionally dogs will have functional carcinoma in the thyroid; more often (about 90% of the time) this is a very aggressive tumor that is invasive and easily metastasizes or spreads to other tissues (esp. the lungs), making prognosis very poor. lung is the essential Respiration organ in air-breathing Animals including most Tetrapods a few Fish and a few Snails The most primitive While surgery is possible, it is often very difficult due to the invasiveness of the mass in surrounding tissue including the arteries, the esophagus, and windpipe. Arteries are Blood vessels that carry blood away from the Heart. The esophagus or oesophagus (see American and British English spelling differences) sometimes known as the gullet, is an organ in The traceartes, or windpipe, is a tube that has an inner diameter of about 20-25 mm and a length of about 10-16 cm in humans It may only be possible to reduce the size of the mass, thus relieving symptoms and also allowing time for other treatments to work.

If a dog does have a benign functional carcinoma (appears in 10% of the cases), treatment and prognosis is no different from that of the cat. The only real difference is that dogs tend to appear to be asymptomic, with the exception of having an enlarged thyroid gland appearing as a lump on the neck.

See also

Footnotes

  1. ^ Faculty of Medicine & Dentistry (2006). Carbimazole is used to treat Hyperthyroidism. Carbimazole is a Pro-drug as after absorption it is converted to the active form Methimazole. Hypothyroidism is the disease state in humans and animals caused by insufficient production of Thyroid hormone by the Thyroid gland. Goitrogens are substances that suppress the function of the Thyroid gland by interfering with Iodine uptake which can as a result cause an enlargement of the thyroid Graves' ophthalmopathy, also known as Graves' thyroid-associated or dysthyroid orbitopathy or exophthalmos, is an Graves' disease is a Thyroid disorder characterized by goiter, Exophthalmos, "orange-peel" skin and Hyperthyroidism. Course-Based Physical Examination - Endocrinology -- Endocrinology Objectives (Thyroid Exam). Undergraduate Medical Education. University of Alberta. Retrieved on 2007-01-28. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 1077 - Walk to Canossa: The Excommunication of Henry IV Holy Roman Emperor is lifted
  2. ^ Berglund J, Christensen SB, Dymling JF, Hallengren B (1991). "The incidence of recurrence and hypothyroidism following treatment with antithyroid drugs, surgery or radioiodine in all patients with thyrotoxicosis in Malmö during the period 1970-1974". J. Intern. Med. 229 (5): 435–42. PMID 1710255.  
  3. ^ Esfahani AF, Kakhki VR, Fallahi B, et al (2005). "Comparative evaluation of two fixed doses of 185 and 370 MBq 131I, for the treatment of Graves' disease resistant to antithyroid drugs". Hellenic journal of nuclear medicine 8 (3): 158–61. PMID 16390021.  
  4. ^ Markovic V, Eterovic D (2007). "Thyroid echogenicity predicts outcome of radioiodine therapy in patients with Graves' disease". J. Clin. Endocrinol. Metab. 92 (9): 3547–52. doi:10.1210/jc.2007-0879. A digital object identifier ( DOI) is a permanent identifier given to an Electronic document. PMID 17609305.  
  5. ^ Susan Little (2006). Feline Hyperthyroidism (PDF). Winn Feline Foundation. Retrieved on 2007-01-28. Year 2007 ( MMVII) was a Common year starting on Monday of the Gregorian calendar in the 21st century. Events 1077 - Walk to Canossa: The Excommunication of Henry IV Holy Roman Emperor is lifted

External links

For Humans
For Felines

Dictionary

hyperthyroidism

-noun

  1. (medicine) The excessive production of hormones by the thyroid.
  2. (pathology) The pathological condition resulting from these excess hormones.
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