Thyroid Gland And Thyroid Hormone Synthesis

thyroid gland gland gland secreter secreteral secreter Gland And thyroid gland Hormone tax write-offHypothyroid secretorism is a condition characterized by ab sanely moo substance of the thyroid endocrine secretory electric organ deductive reasoning. This whitethorn be due to a thyroid trouble or any other reason. Thyroid endocrine gland affects growth, development, and many cellular processes. Inadequate thyroid hormone has many consequences for the torsoThyroid gland and thyroid hormone synthesisThyroid gland has two lobes affiliated by an isthmus. It attaches to the thyroid cartilage and trachea. on that pointfore it moves with swal patheticing. Thyroid gland consists of follicles lie by a cuboidal epithelial cell layer. These follicles filled with colloids.Parafollicular cells find in between follicular cells which secrete calcitonine.Thyroid gland synthesizes principally two hormones. They be L- tetraiodothyronine/tetraiodothyronine (T4) and triiodothyronin e (T3).T3 is the active form that acts at the cellular train and T4 is the prohormone.Iodide enters the thyroid follicles primarily by dint of a transporter. Thyroid hormone synthesis put acrosss in the follicular space through a series of reactions, many of which argon peroxides-mediated. Thyroid hormones stored in the colloid in the follicular space that is released from Thymoglobulin by a hydrolysis reaction which occur inside the thyroid cell.E.g. Thyroglobulin (Tgb), monoiodotyrosine (MIT), diiodotyrosine (DIT),Triiodothyronine (T3), tetraiodothyronine (T4).If at that place is hereditary defect of enzyme in supra process, Thyroid hormone synthesis could non occur. So its leads to congenital thyromegaly and often go outs in hypothyroidism.Regulation of the synthesis of thyroid hormonesThyroid hormone synthesis is regulated by another gland located in the brain called pituitary. In snatch the pituitary gland in berth regulated by the thyroid hormone via feedback mechanis m and other gland called hypothalamus. The hypothalamus secretes thyrotropin hormone ( thyrotropin-releasing factor), which give a signal to the pituitary gland to release thyroid stimulating hormone (thyrotropin). thyrotrophin in turn sends a signal to the thyroid gland to release thyroid hormone. If both(prenominal) defect occurs in one of these levels, a neediness of production of thyroid hormones throne cause a inadequateness of thyroid hormone (hypothyroidism).Hypothalamus TRHdown arrowPituitary- thyrotrophindown arrowThyroid- T4 and T3The outrank of thyroid hormone synthesis is regulated by the pituitary gland. If there is an deficient amount of thyroid hormone circulating in the body to conventionality operate oning, the release of thyrotrophic hormone from the pituitary join ond in graze to experience to a greater extent thyroid hormone. However, when there is a large amount of thyroid hormones in circulation, thyrotrophic hormone level decreases and pituitary attempts to reduce the production of thyroid hormone. In people with hypothyroidism make believe low levels of circulating thyroid hormones. physiological effects of thyroid hormones- Cardiovascular system increased cardiac outfit and lovingness rate.- skeletal system increased bone turnover and resorption.- respiratory maintains normal hypoxic and Hypercapnic drive in respiratory centre.- Gastro in tryoutinal increases gut motility.- fall increases red rail line cell 2, 3-BPG facilitating Oxygen release to tissues.- Neuromuscular increases bucket along of muscle contraction and relaxation and muscle protein turnover.-Metabolism of carbohydrates increases hepatic Gluconeogenesis/glycolysis and intestinal glucose Absorption.- Metabolism of lipids increased lipolysis and Cholesterol synthesis and degradation.- Sympathetic nervous tissue increases catecholamine Sensitivity and -adrenergic receptor numbers in heart, skeletal muscle, adipose cells and lymphocytes.Reduces cardiac -adrenergic receptors.If there is a defect in the synthesis or mandate pathways or thyroid lead to many disorders. They ar mainly motley integrity in two parts. They are hyperthyroidism and hypothyroidism. Hyperthyroidism, or an overactive thyroid, is the overrun of thyroid hormones T3 and T4, and to the highest degree often caused by the development of Graves ailment which is an autoresistant illness in which antibodies are make growd which stimulate the thyroid gland produces excessive amounts of thyroid hormones. This disease privy lead to the development of nephrotoxic goiter due to the growth of the thyroid gland in receipt to the absence of negative feedback mechanisms. This is manifested by symptoms such as thyroid goiter, jut out eyes (exopthalmos), palpitations, excessive sweating, diarrhea, weight vent, muscle weakness and un inveterate predisposition to heat. Appetite is increased.Classification of HypothyroidismHypothyroidism is often classified by association with the indicated organ dys lickTypeOriginPrimaryThyroid glandThe to the highest degree prevalent forms are Hashimotos thyroiditis which is an autoimmune disease and squeeze out be occur in radioiodine therapy for hyperthyroidism.SecondaryPituitary glandOccurs if the pituitary gland does not release enough thyroid-stimulating hormone (TSH) to stimulate the thyroid gland to produce enough thyroid hormones. Although not every case of second-string hypothyroidism has a clear-cut case, it is comm scarcely caused by damage to the pituitary gland, as by a tumor, radiation, or surgery. Secondary hypothyroidism accounts for less than 5% or 10% of hypothyroidism cases.TertiaryHypothalamusResults when the hypothalamus fails to produce sufficientThyrotropin-releasing hormone (TRH). TRH prompts the pituitary gland to produce thyroid-stimulating hormone (TSH). Hence whitethorn also be barriered hypothalamic-pituautoimmuneAtrophic (autoimmune) hypothyroidism. The closely p revalent cause of hypothyroidism and the associated with antithyroid auto antibodies leads to lymphoid infiltration Cancer and unconstipatedtually atrophy and fibrosis. It has been six Times to a greater extent common in women and the incidence increaseswith age. This nooky be associated with other autoimmune Diseases such as mischievous anemia, vitiligo and other endocrine disorders. In nigh cases, intermittent Hypothyroidism occurs when recovering from illness, antibodies which block the TSH receptor can any(prenominal)times be involvedin the etiology.Hashimotos thyroiditis.This form of autoimmune thyroiditis, again, more common in women and the most common in the late. The average age is atrophic changes with regeneration, star(p) to the formation of goiter. This may be usually firm and base hit scarce can vary from soft to hard. TPO antibodies very high amount ( coulomb0 IU / L). Patients can be euthyroid or hypothyroid, except they can pass throughthe initial phase of the toxic Hashi toxicity, Levothyroxine therapy. The goiter may reduce the even if the patient does not Hypothyroid.Postpartum thyroiditis.Typically, this is a temporary phenomenon Observed afterward pregnancy. It can cause hyperthyroidism, Hypothyroidism or the two sequences. It is believed to cause changes in the immune system necesnecessary.In case of pregnancy, and histologically lymphocytic thyroiditis.The process is usually self-limiting, all when when Conventional antibodies are there is a strong chance this affair of permanent hypothyroidism. Postpartum Thyroiditis may be misdiagnosed as postnatal effect. Thyroid function test is done to detect this situation.Defects in hormone synthesis atomic number 53 deficiency. Dietary iodine deficiency still exists in some areas as endemic goiter where goiter, occasionally massive is common. Patients may be euthyroid or hypothyroidism attending on the severity of iodine deficiency. The mechanism is considered borderline hypothy roidismleading to TSH stimulation and thyroid enlargement against iodine deficiency continues. Iodine deficiency is this still a problem in the Netherlands, the Western peaceable and South. East Asia for example, the mountainous regions of the Himalayas and Africa. some(prenominal) countries affected by iodine deficiency, for example, chinaware and Kazakhstan take measures providing iodinein salt, but others, such as Russia, hire not yet done so. Of The 500 million with iodine deficiency in India around 2 million suffering from cretinism.Dyshormonogenesis is a grand disease is due to genetics. Defects in the synthesis of thyroid hormones, patients Develop hypothyroidism with goiter. one particular family Form is associated with sensorineural hearing loss due to the removal Mutation of chromosome 7, resulting in a defect Transporter Pendrin (Pendred syndrome author).Hypothyroidism causes many symptoms. The term myxedema refers to the accumulation of mucopolysaccharides.In the subcutaneous tissue. The perfect pictures are Slow in working, dry hairsbreadth, thick- kowtowned, deep region, Weight gain, cold intolerance, bradycardia, and constipation. These features make the diagnosis easy. Milder symptoms, however, more common and difficult to distinguish from other causes Nonspecific tiredness. Many of the cases on the biochemical detectionScreeningParticular difficulties in diagnosis may occur in certain circumstances- Children with hypothyroidism may not classical Properties, but often have a slow growth rate, poor people School performance and sometimes arrests of pubertal Development.- Young women with hypothyroidism may not visual aspect obvious signs. Hypothyroidism is excluded in all Patients with oligomenorrhea / amenorrhea, Menorrhagia, infertility and hyperprolactinemia.- the elderly show many clinical features that are difficult Distinct from normal aging. investigating of chief(a) hypothyroidismThe Serum TSH is the examination of choice, a high TSH level Confirmed primary hypothyroidism. A low relinquish T4 level confirms the hypothyroidism is (and is also essential for TSH to close a deficiency and clinical hypothyroidism is strongly suspectedand TSH is normal or low).Thyroid and other organ-specific antibodies are present.Other exceptions are the following- Anemia, usually normochromic and normocytic In type but can macrocytic (sometimes this is by Associated pernicious anemia) or microcytic (in women, By menorrhagia)- increased serum aspartate transferase levels, from Muscle and / or liver- increased serum creatine kinase levels, with associated myopathy- hyper cholesterolemia and hypertriglyceridemia- Hyponatremia due to an increase in ADH and reduced ingenuous piddle clearance. intercessionReplacement therapy with levothyroxine (thyroxine, that is to say, T4) is Data for life. The lay outing dose will depend upon the severity of the failure and the age and condition of the patient, oddly their cardiac funct ion 100g per day during the Young and fit, 50g (up to 100g after 2-4 weeks) for the small, old or weak. Patients with ischemic heart disease Illness an even lower initial dose, especially if the Hypothyroidism is a voiceless and prolonged. Most makesWould then start with daily 25g and execute serial ECG, increasing the dose at 3 to 4-week intervals as angina pectoris Not occur or worsen and the ECG is not Deteriorate.monitorThe goal is to recover well at bottom T4 and TSH The normal range. The sufficiency of the backup man is reviewed Clinical and thyroid function tests after at least(prenominal) 6 weeks at a constant dose. If serum TSH the Great Compromiser high, the dose of T4 Should is increased in increments of 25-50 g the tests Repeated 6-8 week intervals until TSH returns to normal. Complete suppression of TSH should be avoided atrial fibrillation and the guess of osteoporosis. The usual The Maintenance dose is 100 to 150 g administered as a single daily Dose. An annual thyroid function test is pep uped this is usually done in the first line, often assisted and in reception to the district thyroid registers.Clinical improvement T4 cannot start 2 weeks or more and complete resolution of symptoms 6 months. The desire for lifelong therapy should be emphasized and the possibility of other autoimmune endocrine disease development, in particular Addisons disease or pernicious anemia,Should be considered. During pregnancy, an increase of T4 Dosage of about 25-50g is often necessary to maintain normal TSH and the need for deputy during optimal. Pregnancy is highlighted by the finding of the reduction of Cognitive function in children of mothers with elevated TSH during pregnancy. A fewer patients with primary hypothyroidism grumbleincomplete symptomatic response to T4 replacement. Combination T4 and T3 replacement is advocated in this Context, but randomized clinical trials show no consistent Benefit from the feel of life symptoms. Borderli ne hypothyroidism or Compensated euthyroidism Patients are often seen with a low-normal serum T4 levels and discountly elevated TSH values. Sometimes this follows surgery or radioactive iodine therapy when it can be reasonably seen as compensatory. Treatment with levothyroxine is normally recommended where the TSH is consistently above 10 mu / L, or if accomplishable symptoms, high titers of thyroid Antibodies or lipid abnormalities are present.When the TSH is only marginally increased, the tests must be repeated trine to six Months later. innovation to overt hypothyroidism is more common in men or TPO antibodies are present inPractice, vague symptoms in patients with marginal Elevated TSH (less than 10 mu / L) noble-mindedly responds to portion outment, However, a therapeutic trial of substitution may be required to confirm that the symptoms are not related to the thyroid gland.It is also is considered to be the best time (TSH level normalization, the ideal case, the former) Pregnancy, in order to avoid the side effects of the fetus.Myxedema torpor toilsome hypothyroidism, especially in the elderly, may be with confusion and even coma. Myxedema coma is very rare. Low temperature is often there, the patient may have severe heart failure, hypoventilation, hypoglycemia, and hyponatriemia.The best interference Controversial, there is no data, most doctors recommend T3 oral or intravenous injection, a dose of 2, and 5-5 grams every 8 hours then, such as the above-mentioned increase. High-dose intravenous cannot be used. Other measures, although there is no proof of Include- Oxygen (by ventilation if necessary)- monitoring of cardiac output and pressure- Gradual warming- Hydrocortisone 100 mg intravenously 8-hour- Glucose infusion to avoid hypoglycemia.Myxedema madness Depression is common in hypothyroidism but rarely with severe hypothyroidism in the elderly can the patient be said demented or psychotic, sometimes with big(a) delusions. This may occur sh ortly after starting T4 replacement.Screening for hypothyroidism- the incidence of congenital hypothyroidism is Approximately 1 in 3500 births. untreated, severe Hypothyroidism produces permanent neurologic and Intellectual damage (cretinism). Routine screening of the newborn with a bloodstain, same Guthrie test, a high TSH level as an indicator of primary detecting Hypothyroidism is efficient and cost effective cretinism is prevented if T4 is started within the first few months of life.- screening of elderly patients for thyroid dysfunction a low pick-up rate and is controversial and not on-line(prenominal)ly recommended. However, patients who have undergone Thyroid surgery or radioactive iodine should receive Regular thyroid function tests, should be as those who Lithium or amiodarone therapy.Signs and symptomsearly hypothyroidism is often asymptomatic, can have very mild symptoms. Subclinical hypothyroidism normal levels of thyroid hormones, thyroxin (T4) and triiodo thyronine (T3), moderate to high thyroid-stimulating hormone, thyroid stimulating hormone (TSH) conditions. TSH and low free T4 at a higher level the symptoms are more obvious in clinical hypothyroidism.Hypothyroidism may be associated with the following symptoms other(a) cold intolerance, increased sensitivity to cold Constipation weight gain, body of water retention bradycardia (low heart rate less than 65 times per minute) grind decreased sweating Muscle cramps and joint pain dry, itchy skin thin, brittle nails Quick thoughts depression muscle tension difference (hypotonia) distaff infertility and problems in the menstrual cycleHyperprolactinemia and galactorrhea elevated serum cholesterolLate goiter slow speech and a hoarse, breaking voice deepening of the voice can also be noticed. Reinke edema. Dry tumescent skin, especially in the face Thinning of the outer third of the eyebrows (sign of Hertoghe) catamenial cycle abnormalities Low basal body temperature thyroid related depressi onUncommonImpaired memoryImpaired cognitive function (brain fog) and inattentiveness.A slow heart rate with ECG changes including low voltage signals. hurt cardiac output and decreased contractilityReactive ( post-prandial) hypoglycemiaHair lossslow reflexesAnemia caused by stricken hemoglobin synthesis (decreased EPO levels), impaired intestinal iron and folate preoccupation or B12 deficiency from pernicious anemiaYellowing of the skin due to impaired conversion of beta-carotene to vitamin A (carotoderma) problem swallowing(dysphagia)Shortness of breath with a shallow and slow respiratory pattern(dyphnea)increase need for sleepIrritability and mood instabilityImpaired nephritic function with decreased glomerular filtration ratemyxedema madness (a rare presentation)Decreased libido due to impairment of testicular testosterone synthesisImpairment of peck sensation and anosmiaPuffy face, hands and feet (late, less common symptoms)Gynecomastia(enlarge breast tissue) exhalation of hearingDiagnosisthyroid function testthe only constitution test diagnosis of primary hypothyroidism is thyroid stimulating hormone (TSH) and free thyroxin (T4) level. However, these levels can be varying without thyroid disease.High TSH levels, the thyroid gland does not produce enough thyroid hormone levels (primarily thyroxin (T4) and a small amount of iodine Thyroid three original leucine (T3)). However, measuring just TSH can diagnose secondary and tertiary thyroid function loss, resulting in the following recommended a blood test, if the TSH is normal hypothyroidism remains skepticalFree triiodothyronine (ft3)Free thyroxin (ft4)Total T3Total T4Additionally, the following measurements may be neededFree T3 from 24-hour urine catchAntithyroid antibodies for evidence of autoimmune diseases that may be damaging the thyroid glandSerum cholesterol which may be elevated in hypothyroidismProlactin as a widely available test of pituitary functionTesting for anemia, including ferrit inBasal body temperatureExams and TestsA physical examination may reveal a littler than normal thyroid gland, although sometimes the gland is normal size or even enlarged (goiter). The examination may also reveal brittle nailsCoarse facial featuresPale or dry skin, which may be cool to the touchSwelling of the arms and legsThin and brittle hairA chest x-ray may show an enlarged heart. laboratory tests to determine thyroid function includeTSH testT4 testLab tests may also revealAnemia on a complete blood count (CBC)Increased cholesterol levelsIncreased liver enzymesIncreased prolactinLow sodiumTreatmentthe treatment of hypothyroidism is anticlockwise forms of thyroxin (thyroid hormone) (L-T4) and triiodo thyroxin liothyronine (L-T3). Thyroxin is a name, and in the USA, the most common form of thyroxin tablets. Thyroxin is a doctor of the most common drugs, wherein a synthetic thyroid hormone predetermined. This medicine can improve symptoms of thyroid deficiency such as speech delay , lack of energy, weight gain, hair loss, dry skin, cold feeling. This will also jock in the treatment of goiter. It can also be used to treat certain types of thyroid cancer, surgery and other medicines. Both synthetic and animate being thyroid tablets available, and may be required in patients with the additional thyroid hormone. Daily doses of thyroid hormone, doctors can monitor blood pressure, in order to help ensure that the correct dose. Thyroxin is the best 30-60 minutes onward breakfast, because some foods can reduce acculturation. Calcium can interfere with absorption levothryoxine. Compared with water, the coffee can be reduced about 30% of the absorption of thyroxin. Some patients may be anti-thyroxin, in fact, they do not have good absorption sheet to solve the problem by spraying. There are several different treatment options for thyroid replacement therapyT4 only such treatment manners include supplementary levothyroxin separately, a synthetic form. This is the current standard treatment of mainstream medicine.A junto of T4 and T3 in This treatment method involves the combination simultaneously manage two synthetic L-T4 and L-T3.Dried thyroid bow outDried thyroid extract is an animal thyroid extract the most common is from porcine sources. It is also a combination therapy, containing a natural form of L-T4 and L-T3.Dealing with controversialT4 T3 generation has been investigating the potence benefits, but has proved to be no conclusive combination therapy benefit. testing ground Medicine Practice Guidelines in 2002, the the clinical biochemical state of the U.S. subject area Academy of Sciences during pregnancy L-T4 dose should be increased (usually 50 micrograms / day) retained at 0.5 2.0 mIU / L and serum serum TSH FT4 within the normal reference interval the upper third. Doctors tend to assume that if your TSH is in the normal range, sometimes defined as high as 5.5 MIU / L has no effect on fertility. But there is an approximately 1.0 MIU / L, TSH level in healthy pregnant womenSubclinical hypothyroidismthere are a series of biochemical and point thyroxin treatment, the typical treatment of hypothyroidism symptoms views. Reference range has been debated. As of 2003, the American Association of Clinical Endocrinologists (ACEE) that within the normal range of 0.3-3.0 MIU / L.There is always an excess risk of hyperthyroidism. Some studies suggest that subclinical hypothyroidism does not require treatment. In 2007, the Cochrane Collaboration, a meta-analysis run aground that, in addition to the no benefit of thyroid hormone replacement lipids and left ventricular function in 2002 meta-analysis checks whether subclinical hypothyroidism may increase the risk of heart disease increase, some of the parameters previously thought, a slight increase, and recommended to be updated for the current recommendations for further research with the end point of coronary thrombosis heart disease.Replacement therapythe connect ion has been a slow release combination of T3 and T4, supporters will be able to thyroid dysfunction symptoms and functional character of life. This is still a matter of debate, refused by the traditional checkup community.Remember, the consequential thing when are taking thyroid hormone are do not stop taking the drugs, and when you feel better. Continue the medication completely guidance of a doctor. If you change the brand of thyroid drugs, let your doctor know. Your levels may need to be checked.Some dietary changes can change your body absorb thyroid drugs. Contact your doctor, if you eat a handle of soy products, or in the high-fiber diet. Thyroid medicine best on an empty stomach, and if any other drugs before one hour. do not take the thyroid hormone supplement fiber, calcium, iron, multivitamins, aluminum hydroxide, sulfuric panelling agent, colestipol, or in combination with a bile acid drugs.You start taking replacement therapy, the doctor tells you, if you have any symptoms of increased thyroid activity (hyperthyroidism), such asPalpitationsRapid weight loss self-consciousness or shakinessSweatingMyxedema coma is a medical emergency the thyroid hormone the body becomes very low. Intravenous replacement thyroid hormone and steroids. Some patients may need support therapy (oxygen, airing assistance, fluid replacement) and intensive care.Outlook (prognosis)in most cases, thyroid levels to normal, and hold treatment. However, thyroid hormone replacement for the rest of life.Myxedema coma can result in death.Possible complicationsHypothyroidism, myxedema coma, the most severe form is rare. This can be caused by infection, illness, exposure to cold, or certain medications in untreated hypothyroidism.The symptoms and signs of myxedema coma include room temperature Reduce breathing low blood pressure hypoglycemia unresponsiveOther complications include tenderness disease Increased risk of infection Infertility abortionUntreated hypothyroidism are a t increased risk gave birth to birth defects heart disease, the higher the level of LDL (bad cholesterol) heart failureToo a great deal thyroid hormone treatment are at risk of angina or a heart attack, as well as the risk of osteoporosis(the bone thinning).