Bromocriptine Health Dictionary

A noncancerous tumour of the pituitary gland that causes overproduction of prolactin. In women, this may result in galactorrhoea, amenorrhoea, or infertility. In men, it may cause impotence and gynaecomastia. In either sex, it may cause headaches, diabetes insipidus, and, if the tumour presses on the optic nerves, loss of the outer visual field. Diagnosis is made from blood tests and CT scanning or MRI of the brain. Treatment may involve removal of the tumour, radiotherapy, or giving the drug bromocriptine.... prolactinoma

A disorder caused by the increased secretion of growth hormone by an ADENOMA of the anterior PITUITARY GLAND. It results in excessive growth of both the skeletal and the soft tissues. If it occurs in adolescence before the bony epiphyses have fused, the result is gigantism; if it occurs in adult life the skeletal overgrowth is con?ned to the hands, feet, cranial sinuses and jaw. Most of the features are due to overgrowth of the cartilage of the nose and ear and of the soft tissues which increase the thickness of the skin and lips. Viscera such as the thyroid and liver are also affected. The overgrowth of the soft tissues is gradual.

The local effects of the tumour commonly cause headache and, less frequently, impairment of vision, particularly of the temporal ?eld of vision, as a result of pressure on the nerves to the eye. The tumour may damage the other pituitary cells giving rise to gonadal, thyroid or adrenocortical insu?ciency. The disease often becomes obvious in persons over about 45 years of age; they may also complain of excessive sweating, joint pains and lethargy. The diagnosis is con?rmed by measuring the level of growth hormone in the serum and by an X-ray of the skull which usually shows enlargement of the pituitary fossa.

Treatment The most e?ective treatment is surgically to remove the pituitary adenoma. This can usually be done through the nose and the sphenoid sinus, but large adenomas may need a full CRANIOTOMY. Surgery cures about 80 per cent of patients with a microadenoma and 40 per cent of those with a large lesion; the rate of recurrence is 5–10 per cent. For recurrences, or for patients un?t for surgery or who refuse it, a combination of irradiation and drugs may be helpful. Deep X-ray therapy to the pituitary fossa is less e?ective than surgery but may also be helpful, and recently more sophisticated X-ray techniques, such as gamma knife irradiation, have shown promise. Drugs – such as BROMOCRIPTINE, capergoline and quiangoline, which are dopamine agonists – lower growth-hormone levels in acromegaly and are particularly useful as an adjunct to radiotherapy. Drugs which inhibit growth-hormone release by competing for its receptors, octeotride and lanreotride, also have a place in treatment.

See www.niddk.nih.gov/health/endo/pubs/ acro/acro.htm

www.umm.edu/endocrin/acromegaly.htm... acromegaly

This is a syndrome in women, characterised by irregular intermittent bouts of generalised swelling. Sometimes the ?uid retention is more pronounced before the menstrual period (see MENSTRUATION). The eyelids are pu?y and the face and ?ngers feel sti? and bloated. The breasts may feel swollen and the abdomen distended, and ankles may swell. The diurnal weight gain may exceed 4 kg. The underlying disturbance is due to increased loss of ?uid from the vascular compartment, probably from leakage of protein from the capillaries increasing the tissue osmotic pressure. Recent evidence suggests that a decrease in the urinary excretion of DOPAMINE may contribute, as this has a natriuretic action (see NATRIURESIS). This may explain why drugs that are dopamine antagonists, such as chlorpromazine, may precipitate or aggravate cyclical oedema. Conversely, bromocriptine, a dopamine agonist, may improve the oedema.... cyclical oedema

Organs whose function it is to secrete into the blood or lymph, substances known as HORMONES. These play an important part in general changes to or the activities of other organs at a distance. Various diseases arise as the result of defects or excess in the internal secretions of the di?erent glands. The chief endocrine glands are:

Adrenal glands These two glands, also known as suprarenal glands, lie immediately above the kidneys. The central or medullary portion of the glands forms the secretions known as ADRENALINE (or epinephrine) and NORADRENALINE. Adrenaline acts upon structures innervated by sympathetic nerves. Brie?y, the blood vessels of the skin and of the abdominal viscera (except the intestines) are constricted, and at the same time the arteries of the muscles and the coronary arteries are dilated; systolic blood pressure rises; blood sugar increases; the metabolic rate rises; muscle fatigue is diminished. The super?cial or cortical part of the glands produces steroid-based substances such as aldosterone, cortisone, hydrocortisone, and deoxycortone acetate, for the maintenance of life. It is the absence of these substances, due to atrophy or destruction of the suprarenal cortex, that is responsible for the condition known as ADDISON’S DISEASE. (See CORTICOSTEROIDS.)

Ovaries and testicles The ovary (see OVARIES) secretes at least two hormones – known, respectively, as oestradiol (follicular hormone) and progesterone (corpus luteum hormone). Oestradiol develops (under the stimulus of the anterior pituitary lobe – see PITUITARY GLAND below, and under separate entry) each time an ovum in the ovary becomes mature, and causes extensive proliferation of the ENDOMETRIUM lining the UTERUS, a stage ending with shedding of the ovum about 14 days before the onset of MENSTRUATION. The corpus luteum, which then forms, secretes both progesterone and oestradiol. Progesterone brings about great activity of the glands in the endometrium. The uterus is now ready to receive the ovum if it is fertilised. If fertilisation does not occur, the corpus luteum degenerates, the hormones cease acting, and menstruation takes place.

The hormone secreted by the testicles (see TESTICLE) is known as TESTOSTERONE. It is responsible for the growth of the male secondary sex characteristics.

Pancreas This gland is situated in the upper part of the abdomen and, in addition to the digestive enzymes, it produces INSULIN within specialised cells (islets of Langerhans). This controls carbohydrate metabolism; faulty or absent insulin production causes DIABETES MELLITUS.

Parathyroid glands These are four minute glands lying at the side of, or behind, the thyroid (see below). They have a certain e?ect in controlling the absorption of calcium salts by the bones and other tissues. When their secretion is defective, TETANY occurs.

Pituitary gland This gland is attached to the base of the brain and rests in a hollow on the base of the skull. It is the most important of all endocrine glands and consists of two embryologically and functionally distinct lobes.

The function of the anterior lobe depends on the secretion by the HYPOTHALAMUS of certain ‘neuro-hormones’ which control the secretion of the pituitary trophic hormones. The hypothalamic centres involved in the control of speci?c pituitary hormones appear to be anatomically separate. Through the pituitary trophic hormones the activity of the thyroid, adrenal cortex and the sex glands is controlled. The anterior pituitary and the target glands are linked through a feedback control cycle. The liberation of trophic hormones is inhibited by a rising concentration of the circulating hormone of the target gland, and stimulated by a fall in its concentration. Six trophic (polypeptide) hormones are formed by the anterior pituitary. Growth hormone (GH) and prolactin are simple proteins formed in the acidophil cells. Follicle-stimulating hormone (FSH), luteinising hormone (LH) and thyroid-stimulating hormone (TSH) are glycoproteins formed in the basophil cells. Adrenocorticotrophic hormone (ACTH), although a polypeptide, is derived from basophil cells.

The posterior pituitary lobe, or neurohypophysis, is closely connected with the hypothalamus by the hypothalamic-hypophyseal tracts. It is concerned with the production or storage of OXYTOCIN and vasopressin (the antidiuretic hormone).

PITUITARY HORMONES Growth hormone, gonadotrophic hormone, adrenocorticotrophic hormone and thyrotrophic hormones can be assayed in blood or urine by radio-immunoassay techniques. Growth hormone extracted from human pituitary glands obtained at autopsy was available for clinical use until 1985, when it was withdrawn as it is believed to carry the virus responsible for CREUTZFELDT-JAKOB DISEASE (COD). However, growth hormone produced by DNA recombinant techniques is now available as somatropin. Synthetic growth hormone is used to treat de?ciency of the natural hormone in children and adults, TURNER’S SYNDROME and chronic renal insu?ciency in children.

Human pituitary gonadotrophins are readily obtained from post-menopausal urine. Commercial extracts from this source are available and are e?ective for treatment of infertility due to gonadotrophin insu?ciency.

The adrenocorticotrophic hormone is extracted from animal pituitary glands and has been available therapeutically for many years. It is used as a test of adrenal function, and, under certain circumstances, in conditions for which corticosteroid therapy is indicated (see CORTICOSTEROIDS). The pharmacologically active polypeptide of ACTH has been synthesised and is called tetracosactrin. Thyrotrophic hormone is also available but it has no therapeutic application.

HYPOTHALAMIC RELEASING HORMONES which affect the release of each of the six anterior pituitary hormones have been identi?ed. Their blood levels are only one-thousandth of those of the pituitary trophic hormones. The release of thyrotrophin, adrenocorticotrophin, growth hormone, follicle-stimulating hormone and luteinising hormone is stimulated, while release of prolactin is inhibited. The structure of the releasing hormones for TSH, FSH-LH, GH and, most recently, ACTH is known and they have all been synthesised. Thyrotrophin-releasing hormone (TRH) is used as a diagnostic test of thyroid function but it has no therapeutic application. FSH-LH-releasing hormone provides a useful diagnostic test of gonadotrophin reserve in patients with pituitary disease, and is now used in the treatment of infertility and AMENORRHOEA in patients with functional hypothalamic disturbance. As this is the most common variety of secondary amenorrhoea, the potential use is great. Most cases of congenital de?ciency of GH, FSH, LH and ACTH are due to defects in the hypothalamic production of releasing hormone and are not a primary pituitary defect, so that the therapeutic implication of this synthesised group of releasing hormones is considerable.

GALACTORRHOEA is frequently due to a microadenoma (see ADENOMA) of the pituitary. DOPAMINE is the prolactin-release inhibiting hormone. Its duration of action is short so its therapeutic value is limited. However, BROMOCRIPTINE is a dopamine agonist with a more prolonged action and is e?ective treatment for galactorrhoea.

Thyroid gland The functions of the thyroid gland are controlled by the pituitary gland (see above) and the hypothalamus, situated in the brain. The thyroid, situated in the front of the neck below the LARYNX, helps to regulate the body’s METABOLISM. It comprises two lobes each side of the TRACHEA joined by an isthmus. Two types of secretory cells in the gland – follicular cells (the majority) and parafollicular cells – secrete, respectively, the iodine-containing hormones THYROXINE (T4) and TRI-IODOTHYRONINE (T3), and the hormone CALCITONIN. T3 and T4 help control metabolism and calcitonin, in conjunction with parathyroid hormone (see above), regulates the body’s calcium balance. De?ciencies in thyroid function produce HYPOTHYROIDISM and, in children, retarded development. Excess thyroid activity causes thyrotoxicosis. (See THYROID GLAND, DISEASES OF.)... endocrine glands

Prolactin is the pituitary hormone (see PITUITARY GLAND) which initiates lactation. The development of the breasts during pregnancy is ascribed to the action of OESTROGENS; prolactin starts them secreting. If lactation does not occur or fails, it may be started by injection of prolactin.

The secretion of prolactin is normally kept under tonic inhibition by the secretion of DOPAMINE which inhibits prolactin. This is formed in the HYPOTHALAMUS and secreted into the portal capillaries of the pituitary stalk to reach the anterior pituitary cells. Drugs that deplete the brain stores of dopamine or antagonise dopamine at receptor level will cause HYPERPROLACTINAEMIA and hence the secretion of milk from the breast and AMENORRHOEA. METHYLDOPA and RESERPINE deplete brain stores of dopamine and the PHENOTHIAZINES act as dopamine antagonists at receptor level. Other causes of excess secretion of prolactin are pituitary tumours, which may be minute and are then called microadenomas, or may actually enlarge the pituitary fossa and are then called macroadenomas. The most common cause of hyperprolactinaemia is a pituitary tumour. The patient may present with infertility – because patients with hyperprolactinaemia do not ovulate – or with amenorrhea and even GALACTORRHOEA.

BROMOCRIPTINE is a dopamine agonist. Treatment with bromocriptine will therefore control hyperprolactinaemia, restoring normal menstruation and ovulation and suppressing galactorrhoea. If the cause of hyperprolactinaemia is an adenomatous growth in the pituitary gland, surgical treatment should be considered.... prolactin

Excessive growth (especially in height), resulting from overproduction of growth hormone during childhood or adolescence by a tumour of the pituitary gland (see pituitary tumours). Untreated, the tumour may compress other hormone-producing cells in the pituitary gland, causing symptoms of hormone deficiency (see hypopituitarism). The condition may be treated with drugs such as bromocriptine that block the release of growth hormone, or by surgery or radiotherapy to remove or destroy the tumour. See also acromegaly.... gigantism

n. a dopamine receptor agonist (see dopamine) that is now rarely used alone, or as an adjunct to *levodopa combined with benserazide or carbidopa, to treat Parkinson’s disease. It has other uses and effects similar to those of *bromocriptine.... cabergoline

n. a drug that stimulates *dopamine receptors in the brain and is now rarely used in the treatment of Parkinson’s disease. Possible side-effects include confusion, hallucinations, sleepiness, heart irregularity, nausea, breathing difficulties, and double vision (see also bromocriptine).... pergolide

Spontaneous, persistent production of milk by a woman who is not pregnant or lactating (see lactation), or, very rarely, by a man.

Lactation is initiated by a rise in the level of prolactin, a hormone produced by the pituitary gland. Galactorrhoea is caused by excessive secretion of prolactin due to a pituitary tumour or otherendocrine disease, such as hypothyroidism. Some antipsychotic drugs may also cause excessive secretion. Treatment with bromocriptine suppresses prolactin production, but the underlying cause may also need treatment. galactosaemia A rare, inherited condition in which the body is unable to convert the sugar galactose into glucose due to the absence of a liver enzyme. It causes no symptoms at birth, but jaundice, diarrhoea, and vomiting soon develop and the baby fails to gain weight. Untreated, the condition results in liver disease, cataract, and learning difficulties. The diagnosis is confirmed by urine and blood tests. The major source of galactose is the milk sugar lactose. Lactosefree milk must be used throughout life. gallbladder A small, pear-shaped sac situated under the liver that stores bile. Bile, produced by the liver, passes into the gallbladder via the hepatic and cystic ducts. It is released into the intestine via the common bile duct.... galactorrhoea

A term that is used to indicate the number of pregnancies a womanhas undergone that have resulted in the birth of a baby capable of survival. parkinsonism Any neurological disorder characterized by a mask-like face, rigidity, and slow movements. The most common type is Parkinson’s disease.

Parkinson’s disease A neurological disorder that causes muscle tremor, stiffness, and weakness. The characteristic signs are trembling, rigid posture, slow movements, and a shuffling, unbalanced walk. The disease is caused by degeneration of, or damage to, cells in the basal ganglia of the brain, reducing the amount of dopamine (which is needed for control of movement). It occurs mainly in elderly people and is more common in men.

The disease usually begins as a slight tremor of 1 hand, arm, or leg, which is worse when the hand or limb is at rest. Later, both sides of the body are affected, causing a stiff, shuffling, walk; constant trembling of the hands, sometimes accompanied by shaking of the head; a permanent rigid stoop; and an unblinking, fixed expression. The intellect is unaffected until late in the disease.

There is no cure.

Drug treatment is used to minimize symptoms in later stages.

Levodopa, which the body converts into dopamine, is usually the most effective drug.

It may be used in combination with benserazide or carbidopa.

The effects of levodopa gradually wear off.

Drugs that may be used in conjunction with it, or as substitutes for it, include amantadine and bromocriptine.

Surgical operations on the brain are occasionally performed.

Untreated, the disease progresses over 10 to 15 years, leading to severe weakness and incapacity.

About one third of sufferers eventually develop dementia.... parity

Growths in the pituitary gland. Pituitary tumours are rare, and mostly noncancerous, but tumour enlargement can put pressure on the optic nerves, causing visual defects.

The causes of pituitary tumours are unknown. They may lead to inadequate hormone production, causing problems such as cessation of menstrual periods or reduced sperm production. They may also cause the gland to produce excess hormone. Overproduction of growth hormone causes gigantism or acromegaly; too much thyroid-stimulating hormone (TSH) can lead to hyperthyroidism. Investigations include blood tests, X-rays, MRI of the pituitary, and usually also vision tests. Treatment may be by surgical removal of the tumour, radiotherapy, hormone replacement, or a combination of these techniques. The drug bromocriptine may be used; it can reduce production of certain hormones and shrink some tumours.... pituitary tumours