| hormone, human chorionic gonadotropin | A human hormone made by chorionic cells (in the foetal part of the placenta), hcg is directed at the gonads and stimulates them. Hcg becomes detectable (by immunologic means) within days of the time of fertilization. It therefore forms the foundation of most common pregnancy tests. The level of hcg in maternal serum enters as one component in the double and the triple screens used during pregnancy to assign risks of down syndrome and other foetal disorders. (12 Dec 1998) |
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| hormone, mineralocorticoid | A group of hormones, the most important being aldosterone, that regulate the balance of water and electrolytes (ions such as sodium and potassium) in the body. The mineralocorticoid hormones act specifically on the tubules of the kidney. (12 Dec 1998) |
| hormone, parathormone | Hormone made by the parathyroid gland (behind the thyroid gland in the neck). Parathormone (pronounced para-thor-mone) is critical to calcium and phosphorus balance. Deficiency of parathormone results in abnormally low calcium in the blood (hypocalcaemia). Also call parathyrin. (12 Dec 1998) |
| hormone, parathyrin | See Hormone, parathormone. (12 Dec 1998) |
| hormone, parathyroid | See Hormone, parathormone. (12 Dec 1998) |
| hormone, progesterone | A female hormone, progesterone is the principal progestational hormone. Progestational hormones prepare the uterus (the womb) to receive and sustain the fertilised egg. (12 Dec 1998) |
| hormone receptor assay | A diagnostic test to determine whether a breast cancer's growth is influenced by hormones or if it can be treated with hormones. (09 Oct 1997) |
| hormone replacement therapy | In females, treatment with sex hormones for a number for reasons, including menopause, partial or full hysterectomy, or amenorrhoea.In women, treatment with sex hormones is indicated for a number of reasons, including menopause, partial or full hysterectomy, or amenorrhoea. After menopause, conjugated oestrogens, estradiol, or estrone sulfate are given to reduce pain during intercourse, limit blood vessel effects, and prevent loss of bone mass. After radical hysterectomy, conjugated oestrogens are given for similar reasons. After menopause or partial hysterectomy, progestin is administered at the same time to offset an increased risk of endometrial cancer. In some amenorrhoeas, oestrogen is given to restore menses; if the therapy is unsuccessful, this may indicate the presence of pathology, for instance, pituitary tumour. Benefits for postmenopausal women include a lowered risk of heart attack (oestrogen lowers LDL and raises HDL levels), and prevention of osteoporosis, since the rate of bone loss is directly linked to a drop in oestrogen levels (see perimenopause). Medical opinion about the hazard posed by such therapy remains divided. Some studies have indicated increased incidence of breast cancer; however, a comprehensive 1992 review of the literature contradicted this finding. (05 Mar 2000) |
| hormone, secretin | Hormone made by glands in the small intestine that stimulates pancreatic secretion. The word hormone was coined by the english physiologists wm. M. Bayliss and ernest h. Starling in connection with their discovery of secretin, the first hormone, in 1902. (12 Dec 1998) |
| hormone, t3 | Triiodothyronine, a thyroid hormone. The number 3 is usually in subscript. (12 Dec 1998) |
| hormone,t4 | Thyroxine, a thyroid hormone. The number 4 is usually in subscript. (12 Dec 1998) |
| hormone therapy | Treatment which results in the raising or lowering of hormone levels. Changes in levels can effect some breast cancers, those that need hormones for growth. (16 Dec 1997) |
| hormone, thyroid | Chemical substance made by the thyroid gland which is located in the front of the neck. The thyroid gland uses iodine to make thyroid hormones. The two most important thyroid hormones are thyroxine (t4) and triiodothyronine (t3). (12 Dec 1998) |
| hormone, thyroid stimulating | A hormone produced by the pituitary gland (at the base of the brain) that promotes the growth of the thyroid gland (in the neck) and stimulates it to produce its thyroid hormones. Normally, the rate of thyroid hormone production is controlled by the pituitary. When there are insufficient thyroid hormones in the body for normal functioning of the cells, the pituitary releases tsh. Tsh in turn stimulates the thyroid gland to produce more thyroid hormones. In contrast, when there is excessive amount of thyroid hormones, the pituitary gland stops producing tsh. The tsh level then falls and thyroid hormone production is reduced. This mechanism maintains a relatively constant level of thyroid hormones circulating in the blood. This phenomenon is analogous to a thermostat used for temperature regulation in a room: when the temperature rises, the thermostat shuts the heater off and the room temperature falls back to normal. High levels of thyroid hormones cause the tsh level to fall, resulting in no further stimulation of the thyroid gland. In hyperthyroidism, there are continuously elevated levels of the thyroid hormones. Tsh is also known as thyrotropin. (12 Dec 1998) |
| hormone, thyrotropin | A hormone produced by the pituitary gland (at the base of the brain) that promotes the growth of the thyroid gland (in the neck) and stimulates it. The suffix -tropin indicates an affinity for. Thyrotropin has an affinity for the thyroid. Thyrotropin is known also as thyroid stimulating hormone (tsh). (12 Dec 1998) |