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Wolff–Chaikoff Effect
The Wolff–Chaikoff effect is a presumed reduction in thyroid hormone levels caused by ingestion of a large amount of iodine. It was discovered by Drs. Jan Wolff and Israel Lyon Chaikoff at the University of California, Berkeley: in 1948, they reported that injection of iodine in rats almost completely inhibited organification (thyroglobulin iodination) in the thyroid gland. However, recent research into the study shows that the thyroid hormone levels of the rats were not checked prior to injections. Patients with Graves' disease are more sensitive than euthyroid patients, and iodine has been used to manage Graves' disease. The Wolff–Chaikoff effect is known as an autoregulatory phenomenon that inhibits organification in the thyroid gland, the formation of thyroid hormones inside the thyroid follicle, and the release of thyroid hormones into the bloodstream. This becomes evident secondary to elevated levels of circulating iodide. The Wolff–Chaikoff effect is an effe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Antithyroid Agent
An antithyroid agent is a hormone antagonist acting upon thyroid hormones. The main antithyroid drugs are carbimazole (in the UK), methimazole (in the US), and propylthiouracil (PTU). A less common antithyroid agent is potassium perchlorate. Graves' disease In Graves' disease, treatment with antithyroid medications must be given for six months to two years, in order to be effective. Even then, upon cessation of the drugs, the hyperthyroid state may recur. Side effects of the antithyroid medications include a potentially fatal reduction in the level of white blood cells. A randomized control trial testing single dose treatment for Graves' found methimazole achieved euthyroid state more effectively after 12 weeks than did propylthiouracil (77.1% on methimazole 15 mg vs 19.4% in the propylthiouracil 150 mg groups). But generally both drugs are considered equivalent. A study has shown no difference in outcome for adding thyroxine to antithyroid medication and continuing ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Lugol's Iodine
Lugol's iodine, also known as aqueous iodine and strong iodine solution, is a solution of potassium iodide with iodine in water. It is a medication and disinfectant used for a number of purposes. Taken by mouth it is used to treat thyrotoxicosis until surgery can be carried out, protect the thyroid gland from radioactive iodine, and to treat iodine deficiency. When applied to the cervix it is used to help in screening for cervical cancer. As a disinfectant it may be applied to small wounds such as a needle stick injury. A small amount may also be used for emergency disinfection of drinking water. Side effects may include allergic reactions, headache, vomiting, and conjunctivitis. Long term use may result in trouble sleeping and depression. It should not typically be used during pregnancy or breastfeeding. Lugol's iodine is a liquid made up of two parts potassium iodide for every one part elemental iodine in water. Lugol's iodine was first made in 1829 by the French physicia ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Potassium Iodide
Potassium iodide is a chemical compound, medication, and dietary supplement. It is a medication used for treating hyperthyroidism, in radiation emergencies, and for protecting the thyroid gland when certain types of radiopharmaceuticals are used. In the third world it is also used for treating skin sporotrichosis and phycomycosis. It is a supplement used by people with low dietary intake of iodine. It is administered orally. Common side effects include vomiting, diarrhea, abdominal pain, rash, and swelling of the salivary glands. Other side effects include allergic reactions, headache, goitre, and depression. While use during pregnancy may harm the baby, its use is still recommended in radiation emergencies. Potassium iodide has the chemical formula K I. Commercially it is made by mixing potassium hydroxide with iodine. Potassium iodide has been used medically since at least 1820. It is on the World Health Organization's List of Essential Medicines. Potassium iodide is av ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Jod-Basedow Phenomenon
The Jod-Basedow effect (also Jod-Basedow syndrome and Jod-Basedow phenomenon) is hyperthyroidism following administration of iodine or iodide, either as a dietary supplement, iodinated contrast medical imaging, or as a medication (mainly Amiodarone). Pathophysiology This phenomenon is thus iodine-induced hyperthyroidism, typically presenting in a patient with endemic goiter (due to iodine deficiency), who relocate to an iodine-abundant geographical area. Also, people who have Graves disease, toxic multinodular goiter, or various types of thyroid adenoma are also at risk of Jod-Basedow effect when receiving iodine, because the thyroid will then not respond to the negative feedback from increased thyroid hormones. The source of iodine may be from the diet, administration of the iodinated contrast for medical imaging, or amiodarone (an antiarrhythmic drug). The hyperthyroidism usually develops over 2 to 12 weeks following iodine administration. In some ways the Jod-Basedow phenome ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thyroglobulin
Thyroglobulin (Tg) is a 660 kDa, dimeric glycoprotein produced by the follicular cells of the thyroid and used entirely within the thyroid gland. Tg is secreted and accumulated at hundreds of grams per litre in the extracellular compartment of the thyroid follicles, accounting for approximately half of the protein content of the thyroid gland. Human TG (hTG) is a homodimer of subunits each containing 2768 amino acids as synthesized (a short signal peptide of 19 aminoacids may be removed from the N-terminus in the mature protein). Thyroglobulin is in all vertebrates the main precursor to thyroid hormones, which are produced when thyroglobulin's tyrosine residues are combined with iodine and the protein is subsequently cleaved. Each thyroglobulin molecule contains approximately 100–120 tyrosine residues, but only a small number (20) of these are subject to iodination by thyroperoxidase in the follicular colloid. Therefore, each Tg molecule forms approximately 10 thyroid hormo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Plummer Effect
The Plummer effect is one of several physiological feedforward mechanisms taking place in follicular cells of the healthy thyroid gland and preventing the development of thyrotoxicosis in situations of extremely high supply with iodine. History In 1923 the American physician Henry Stanley Plummer discovered that high-dose iodine may be effective in the treatment of Graves’ disease. Today, “Plummering”, i.e. therapy with Lugol's iodine solution, is one of several emergency measures in the management of severe thyrotoxicosis. Mechanism Via the Plummer effect, a high iodine concentration inhibits the proteolysis of thyroglobulin and the release of pre-formed thyroid hormones from thyroid follicles. Therefore, its mechanism differs from that of the Wolff–Chaikoff effect, where iodine inhibits the uptake of iodine in thyroid cells and the formation of thyroid hormones, and of the dehalogenase inhibition effect, where high iodine levels block deiodinases and other deha ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Amiodarone
Amiodarone is an antiarrhythmic medication used to treat and prevent a number of types of cardiac dysrhythmias. This includes ventricular tachycardia (VT), ventricular fibrillation (VF), and wide complex tachycardia, as well as atrial fibrillation and paroxysmal supraventricular tachycardia. Evidence in cardiac arrest, however, is poor. It can be given by mouth, intravenously, or intraosseously. When used by mouth, it can take a few weeks for effects to begin. Common side effects include feeling tired, tremor, nausea, and constipation. As amiodarone can have serious side effects, it is mainly recommended only for significant ventricular arrhythmias. Serious side effects include lung toxicity such as interstitial pneumonitis, liver problems, heart arrhythmias, vision problems, thyroid problems, and death. If taken during pregnancy or breastfeeding it can cause problems in the fetus. It is a class III antiarrhythmic medication. It works partly by increasing the time before a he ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Hypothyroidism
Hypothyroidism (also called ''underactive thyroid'', ''low thyroid'' or ''hypothyreosis'') is a disorder of the endocrine system in which the thyroid gland does not produce enough thyroid hormone. It can cause a number of symptoms, such as poor ability to tolerate cold, a feeling of tiredness, constipation, slow heart rate, depression, and weight gain. Occasionally there may be swelling of the front part of the neck due to goiter. Untreated cases of hypothyroidism during pregnancy can lead to delays in growth and intellectual development in the baby or congenital iodine deficiency syndrome. Worldwide, too little iodine in the diet is the most common cause of hypothyroidism. Hashimoto's thyroiditis is the most common cause of hypothyroidism in countries with sufficient dietary iodine. Less common causes include previous treatment with radioactive iodine, injury to the hypothalamus or the anterior pituitary gland, certain medications, a lack of a functioning thyroid at bi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Thyroidectomy
A thyroidectomy is an operation that involves the surgical removal of all or part of the thyroid gland. In general surgery, endocrine or head and neck surgeons often perform a thyroidectomy when a patient has thyroid cancer or some other condition of the thyroid gland (such as hyperthyroidism) or goiter. Other indications for surgery include cosmetic (very enlarged thyroid), or symptomatic obstruction (causing difficulties in swallowing or breathing). Thyroidectomy is a common surgical procedure that has several potential complications or sequelae including: temporary or permanent change in voice, temporary or permanently low calcium, need for lifelong thyroid hormone replacement, bleeding, infection, and the remote possibility of airway obstruction due to bilateral vocal cord paralysis. Complications are uncommon when the procedure is performed by an experienced surgeon. The thyroid produces several hormones, such as thyroxine (T4), triiodothyronine (T3), and calcitonin. After ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Basal Metabolic Rate
Basal metabolic rate (BMR) is the rate of food energy, energy expenditure per unit time by endotherm, endothermic animals at rest. It is reported in energy units per unit time ranging from watt (joule/second) to ml O2/min or joule per hour per kg body mass J/(h·kg). Proper measurement requires a strict set of criteria to be met. These criteria include being in a physically and psychologically undisturbed state and being in a Thermal neutral zone, thermally neutral environment while in the post-absorptive state (i.e., not actively digesting food). In Bradymetabolism, bradymetabolic animals, such as fish and reptiles, the equivalent term standard metabolic rate (SMR) applies. It follows the same criteria as BMR, but requires the documentation of the temperature at which the metabolic rate was measured. This makes BMR a variant of standard metabolic rate measurement that excludes the temperature data, a practice that has led to problems in defining "standard" rates of metabolism for ma ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Methimazole
Thiamazole, also known as methimazole, is a medication used to treat hyperthyroidism. This includes Graves disease, toxic multinodular goiter, and thyrotoxic crisis. It is taken by mouth. Full effects may take a few weeks to occur. Common side effects include itchiness, hair loss, nausea, muscle pain, swelling, and abdominal pain. Severe side effects may include low blood cell counts, liver failure, and vasculitis. Use is not recommended during the first trimester of pregnancy due to the risk of congenital anomalies, but it may be used in the second trimester or third trimester. It may be used during breastfeeding. Those who developed significant side effects may also have problems with propylthiouracil. Thiamazole is a thioamide and works by decreasing the production of thyroid hormones. Thiamazole was approved for medical use in the United States in 1950. It is on the World Health Organization's List of Essential Medicines. It is available as a generic medication. It i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
