Thyroid Hormone: From 1 Different Sources
an iodine-containing substance, synthesized and secreted by the thyroid gland, that is essential for normal metabolic processes and mental and physical development. There are two thyroid hormones, *triiodothyronine and *thyroxine, which are formed from *thyroglobulin. Lack of these hormones gives rise to *cretinism in infants and *myxoedema in adults. Excessive production of thyroid hormones gives rise to *thyrotoxicosis.
A chemical produced in the body by endocrine glands and carried in the blood to other organs where the hormone causes processes to change in the target organ. A chemical messenger.... hormone
A hormone produced by the anterior PITUITARY GLAND which stimulates the formation of follicles in the ovary each menstrual cycle (see OVARIES; MENSTRUATION) and of spermatocytes in the testis (see TESTICLE). It is under hypothalamic control (see HYPOTHALAMUS) and in the female there is feedback inhibition by oestrogens from the developing follicle.... follicle-stimulating hormone
(LH) This is a sugar-bearing protein manufactured by the anterior pituitary. Like a lot of the pituitary hormones, it surges on and off, since constant secretion would overload and deaden receptors. In women, it builds up after menses, stimulating the release of estrogen from the ovaries. Estrogen in turn stimulates the hypothalamus to increase its stimulation of LH from the pituitary, until, a day or two before ovulation, they produce a guitar-amp feedback, and the cells that produce LH start to surge follicle-stimulating hormone (FSH). The egg pops, being replaced by the corpus luteum, which produces progesterone for the next eleven to twelve days. Progesterone inhibits and lowers LH levels, as well as inhibiting levels of estrogen already being produced by the young follicles that will produce next month’s egg. In men, LH is responsible for stimulation of testosterone, although FSH and the testes hormone inhibin are responsible for both the production of sperm and controlling testosterone.... luteinizing hormone
A rare disease that accounts for around 1 per cent of all cancers, cancer of the THYROID GLAND usually presents as an isolated hard nodule in the neck. The rate at which the nodule grows depends upon the patient’s age and type of cancer cell. Pain is not usually a feature, but the increasing size may result in the tumour pressing on vital structures in the neck – for example, the nerves controlling the LARYNX (resulting in hoarseness) and the PHARYNX (causing di?culty in swallowing). If more than one nodule is present, they are likely to be benign, not malignant. Treatment is by surgical removal after which the patient will need to take THYROXINE for the rest of his or her life. Radioactive iodine is usually given after surgery to destroy any residual cancerous cells. If treated early, the outlook is good.... thyroid cancer
Within a few years medical scientists have introduced into the domestic scene a steroid which has changed the whole course of female history. HRT has solved some basic medical problems by making good the loss of oestrogen in a woman’s body when menstruation is finished and her body learns to adjust.
A lack of oestrogen induces hot flushes, night sweats, thinning of the bones (osteoporosis) with possible fractures, and a wide range of physical and emotional disorders.
HRT also prevents the increased frequency of coronary disease which may follow the menopause. With oestrogen only, HRT appears to increase the incidence of cancer of the uterine body. Use of oestrogen and progestogen avoids this.
HRT is available as a tablet, transdermal patch, implant or topical cream. Most women notice temporary improvement in their appearance and hot flushes as long as treatment is continued. HRT is not prescribed by the herbal practitioner. Soya and Hops are a mild alternative.
Side-effects of such treatment include blood pressure rise, weight gain and periods probably continue with a monthly bleed. Elderly women taking HRT for osteoporosis may develop bleeding problems, the risk of blood clot and gall bladder diseases.
Helonias has proved a useful alternative, effective in eliminating excess fluids, reducing hot flushes, and relieving that bloated feeling, thus helping the older woman to live a normal life.
Damiana. 1 heaped teaspoon leaves to each cup boiling water; infuse 5-10 minutes; strain. 1 cup 2-3 times daily for 3-6 weeks.
Sarsaparilla. 1oz (30g) root in 1 pint (500ml) water; simmer gently 20 minutes; strain. 1 cup 2-3 times daily for 3-6 weeks.
Supplementation. Daily. Vitamin E, 400iu. Vitamin B-complex (high potency). Evening Primrose oil capsules, 500mg morning and evening. Dolomite, for Calcium and Magnesium, 2 tablets morning and evening.
Note: An extensive study of breast cancer risks with HRT revealed a positive link between the risk of cancer and length of use. Risk of the disease increased with all types of women using HRT with every year of use. Pre-menstrual women were more than twice at risk. It would appear that oestrogens cannot be taken without risk. (Centre for Disease Control, Atlanta, USA) See: OESTROGENS. ... hormone replacement therapy (hrt)
These are ‘chemical messengers’ that are dispersed by the blood and act on target organs to produce effects distant from their point of release. The main organs involved in hormone production are the PITUITARY GLAND, PANCREAS, ovary (see OVARIES), testis (see TESTICLE), THYROID GLAND, and ADRENAL GLANDS. The release of many hormones is, ultimately, under the control of the central nervous system via a series of inhibiting and releasing factors from the HYPOTHALAMUS. Hormones are involved in maintaining homeostasis: for example, insulin regulates the concentration of glucose in the blood. They also participate in growth and maturation: for example, growth hormone promotes growth and helps to regulate fat, carbohydrate, and protein metabolism; and the sex hormones promote sexual maturation and reproduction. (See also ENDOCRINE GLANDS.)... hormones
These HORMONES control the development of primary and secondary sexual characteristics. They also regulate sex-related functions – for example, menstruation and the production of sperm and eggs. The three main types of sex hormone are androgens, or male sex hormones (see ANDROGEN); OESTROGENS, or female sex hormones; and progesterones, which are involved in pregnancy (see PROGESTERONE).... sex hormones
The largest cartilage in the LARYNX and forms the prominence of the Adam’s apple in front of the neck.... thyroid cartilage
See ACTH.... adrenocorticotrophic hormone
See ADH.... antidiuretic hormone
(LH-RH) The same substance as Follicle-Stimulating-Hormone Releasing Hormone (FSH-RH), both of which are actually Gonadotrophin-Releasing Hormone (GnRH or GRH). Confused? Imagine being an endocrinologist 20 years ago. These (This) are (is) a peptide secreted into the little portal system that drains from the hypothalamus to the pituitary. If it is surged hourly and not too strongly, the pituitary secretes LH and the ovaries secrete estrogen. If it is surged hourly and strongly, the estrogens rise drastically, the pituitary secretes FSH, you pop an egg, start the corpus luteum and begin progesterone secretion. The surge is now slowed to every four or five hours, not too strongly, and the pituitary secretes LH every four or five hours...and the ovaries make progesterone. The same hypothalamic hormone triggers different pituitary responses based on AMPLITUDE and FREQUENCY.... luteinizing-hormone releasing hormone
ACTH is the commonly used abbreviation for CORTICOTROPIN.... acth (adrenocorticotrophic hormone)
See also CORTICOTROPIN. A hormone which is released into the body during stress. Made and stored in the anterior PITUITARY GLAND, ACTH regulates the production of corticosteroid hormones from the ADRENAL GLANDS, and is vital for the growth and maintenance of the adrenal cortical cells. Its production is in part controlled by the amount of HYDROCORTISONE in the blood and also by the HYPOTHALAMUS. ACTH participates in the FEEDBACK MECHANISM of hormone production and actions involving particularly the hypothalamus and pituitary gland. The hormone is used to test adrenal function and treat conditions such as ASTHMA. (See also CUSHING’S SYNDROME.)... adrenocorticotrophic hormone (acth)
See VASOPRESSIN.... antidiuretic hormone (adh)
See OESTRADIOL.... follicular hormone
See under MENOPAUSE.... hormone replacement therapy(hrt)
A hormone secreted by the anterior PITUITARY GLAND which stimulates OVULATION, maturation of the CORPUS LUTEUM, and the synthesis of progesterone by the ovary (see OVARIES) and testosterone by the testis (see TESTICLE).... luteinising hormone
A natural hormone released by the HYPOTHALAMUS gland in the BRAIN. It stimulates the release of GONADOTROPHINS from the PITUITARY GLAND; these control the production of the sex hormones (see ANDROGEN; OESTROGENS).... luteinising hormone-releasing hormone (lhrh)
... thyroid gland, diseases of
A hormone (see HORMONES) produced and released by the HYPOTHALAMUS which stimulates the release of THYROTROPHINSTIMULATING HORMONE (TSH) by the PITUITARY GLAND.... thyrotrophin-releasing hormone (trh)
A hormone (see HORMONES) manufactured and released by the anterior part of the PITUITARY GLAND which stimulates the THYROID GLAND to manufacture and release thyroid hormones (THYROXINE and TRI-IODOTHYRONINE).... thyrotrophin-stimulating hormone (tsh)
A group of hormones produced by the adrenal glands that control the body’s use of nutrients and the excretion of salts and water in the urine.... corticosteroid hormones
A group of hormones released from specialized cells in the stomach, pancreas, and intestine that control various functions of the digestive organs. Gastrin, secretin, and cholecystokinin are the best known of these hormones.... gastrointestinal hormones
These are fats similar to, and usually synthesized from, cholesterol, starting with Acetyl-CoA, moving through squalene, past lanosterol, into cholesterol, and, in the gonads and adrenal cortex, back to a number of steroid hormones. Nearly all of the classic hormones are proteins or smaller peptides; they don’t get inside a cell (the membrane keeps them out); instead, they bind to, and initiate, cell changes from the outside. The exceptions are the thyroxines (from the thyroid) and the steroid hormones. They move into the cell, bind with receptors, and initiate changes in the way a cell regenerates itself or synthesizes new compounds. Because the steroid hormones stimulate cell growth, either by changing the internal structure or increasing the rate of proliferation, they are often called anabolic steroids. Estrogen, an ovarian steroid, when secreted into the bloodstream, will be bound within a short time by internal receptors inside those cells that need estrogen for their growth; the unused portion is partially broken down, mostly in the liver, and partially stored in a less active form by adipose tissue. Since luteinizing hormone from the pituitary is surged in pulses an hour apart, the estrogen is also surged from the reacting ovaries, and by the time more estrogen is available, the binding cells need more; their program of synthesis has run out and needs to be started again. Of course, most steroid hormone reactions are less measured than this, but you get the idea.... steroid hormone
Hormones that stimulate cell activity in the ovaries and testes. Gonadotrophins are essential for fertility. The two most important gonadotrophins are follicle-stimulating hormone (FSH) and luteinizing hormone (LH), which are secreted by the pituitary gland. Another gonadotrophin, HCG (see gonadotrophin, human chorionic), is produced by the placenta during pregnancy. Certain gonadotrophins are used as drugs in the treatment of infertility.... gonadotrophin hormones
A drug that blocks the action of a hormone.... hormone antagonist
A group of blood tests used to evaluate the function of the thyroid gland and to detect or confirm any thyroid disorder. The thyroid hormones T3 and T4 are measured, as well as thyroid-stimulating hormone (TSH), the pituitary gland hormone that stimulates the thyroid gland.... thyroid-function tests
Techniques, such as radionuclide scanning and ultrasound scanning, that are used to provide information about the location, anatomy, and function of the thyroid gland.... thyroid scanning
see Müllerian duct.... anti-müllerian hormone
(CRH) a peptide hypothalamic hormone (of 41 amino acids) stimulating the release of *ACTH (adrenocorticotrophic hormone) from the anterior pituitary. Its own release is suppressed by a *negative feedback loop involving cortisol, and its action is increased by antidiuretic hormone (see vasopressin) and *angiotensin II. It can be administered intravenously as part of the CRH test, during which blood is analysed at 15-minute intervals for one hour for the ACTH response, which is excessive in cases of primary adrenal failure and suppressed in cases of anterior *hypopituitarism.... corticotrophin-releasing hormone
a hormone produced by cells that do not usually produce it. Some tumour cells secrete hormones; for example, small-cell lung cancer cells secrete antidiuretic hormone and cause *hyponatraemia.... ectopic hormone
(GnRH, gonadorelin) a peptide hormone produced in the hypothalamus and transported via the bloodstream to the pituitary gland, where it controls the synthesis and release of pituitary *gonadotrophins. It may be used to test the ability of the pituitary to produce gonadotrophins. *Gonadorelin analogues are used to treat endometriosis, fibroids, some types of infertility, and prostate cancer.... gonadotrophin-releasing hormone
a family of plasma proteins whose function is to bind free hormone molecules to varying degrees and thus reduce their function. Alterations in levels of the binding globulins, for example during pregnancy or ill health, can result in variations in assays of hormone levels in individuals. Examples include thyroid-binding globulin, sex-hormone-binding globulin, and corticosteroid-binding globulin.... hormone-binding globulins
see luteinizing hormone.... interstitial-cell-stimulating hormone
see prolactin.... lactogenic hormone
(luteotrophin) see prolactin.... luteotrophic hormone
(MSH) a peptide hormone produced and secreted by the anterior pituitary gland. In humans it stimulates production and dispersal of melanin in the melanocytes. Alpha-melanocyte-stimulating hormone (?-MSH), which is released by neurons in the hypothalamus, suppresses appetite and regulates energy balance. It also stimulates sexual activity and is involved in regulation of heart rate and blood pressure.... melanocyte-stimulating hormone
(PTH-RP) a protein that is secreted by certain malignant tumours and is the main cause of malignant *hypercalcaemia. PTH-RP, which has effects similar to *parathyroid hormone, stimulates generalized bone resorption and excessive calcium reabsorption in the kidney tubules. It is most commonly produced by lung tumours, squamous-cell carcinomas of other organs, melanomas, and tumours of the breast, liver, pancreas, bladder, and prostate.... parathyroid hormone-related protein
any steroid hormone, produced mainly by the ovaries or testes, that is responsible for controlling sexual development and reproductive function. *Oestrogens and *progesterone are the female sex hormones; *androgens are the male sex hormones.... sex hormone
(SIADH) a condition of inappropriately high plasma levels of ADH (see vasopressin) with associated water retention, dilutional *hyponatraemia, and the production of highly concentrated urine. Renal, adrenal, thyroid, and hepatic function are normal, as is the volume of circulating blood (euvolaemia). It is caused by a variety of pathological conditions, usually intrathoracic and intracerebral, and also by a number of drugs, including antidepressants, chemotherapy agents, and some of the older antidiabetic agents. The treatment involves fluid restriction, treatment (or removal) of the underlying cause (or drug), and, in severe cases, administration of *demeclocycline to reduce the effects of ADH on the kidney. Very rarely, hypertonic saline is given.... syndrome of inappropriate secretion of antidiuretic hormone
a rarely seen but well-documented alteration in the shape of the nails resembling *clubbing but unique to Graves’ disease (see thyrotoxicosis). It is often associated with formation of new bone seen on X-rays of the hands and wrists, which is said to resemble bubbles along the surface of the bones.... thyroid acropachy
autoantibodies directed against the cells of the thyroid gland, which serve as a marker of autoimmune thyroid disease. There are two main types: antibodies directed against the thyroid peroxidise (TPO) enzyme; and anti-thyroglobulin, directed against the thyroid colloid (see thyroid gland). The highest level of thyroid antibodies is found in *Hashimoto’s disease.... thyroid antibodies
(TSH, thyrotrophin) a hormone, synthesized and secreted by the anterior pituitary gland under the control of *thyrotrophin-releasing hormone, that stimulates activity of the thyroid gland. Raised levels of TSH are found in primary *hypothyroidism. Normal or low TSH levels in the presence of a low serum thyroxine are found in secondary hypothyroidism and the *euthyroid sick syndrome.... thyroid-stimulating hormone
see thyroid crisis.... thyroid storm
(TRH) a hormone from the hypothalamus (in the brain) that acts on the anterior pituitary gland to stimulate the release of *thyroid-stimulating hormone. A preparation of TRH (protirelin) may be given by intravenous injection to test thyroid gland function and to estimate reserves of thyroid-stimulating hormone in the pituitary.... thyrotrophin-releasing hormone
(thyroid storm) a life-threatening condition due to an acute and severe exacerbation of previously undiagnosed or inadequately treated *thyrotoxicosis. It often follows infections, childbirth, nonthyroid surgery, or trauma but can occur without an obvious cause. The presenting features are a fever, severe agitation, nausea and vomiting, diarrhoea, and abdominal pains. An accelerated heart rate and irregularity of the heart rhythm can cause heart failure, and psychotic episodes or coma can result. Blood tests will reveal hyperthyroidism and may also show altered liver function, high blood sugar, high calcium levels, a high white blood cell count, and often anaemia. Treatment is with intravenous fluids, oxygen, antithyroid drugs (such as *carbimazole or *propylthiouracil), high-dose iodide solution (see Lugol’s solution), high-dose steroids, and beta blockers. The patient must be cooled and given antipyretics, such as paracetamol. Any underlying cause must also be treated.... thyroid crisis
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