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| MeshID = D006966 | | | MeshID = D006966 | |
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| {{GS}} | | {{GS}} |
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| {{Hyperprolactinemia}} | | {{Hyperprolactinemia}} |
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| ==Causes==
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| Hyperprolactinaemia may be caused by either disinhibition (e.g. compression of the pituitary stalk or reduced dopamine levels) or excess production from a [[prolactinoma]] (a pituitary gland [[adenoma]] tumour). A prolactin level of 1000–5000mIU/L could be from either mechanism, but >5000mIU/L is likely due to an adenoma with macroadenomas (large tumours over 10 mm diameter) having levels of up to 100,000mIU/L. Hyperprolactinemia inhibits [[gonadotropin-releasing hormone]] (GnRH) by increasing the release of [[dopamine]] from the [[arcuate nucleus]] of the [[hypothalamus]] (dopamine inhibits GnRH secretion), thus inhibiting gonadal steroidogenesis, which is the cause of many of the symptoms described below:
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| ===Physiological causes===
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| Physiological causes (i.e. as result of normal body functioning): [[pregnancy]], [[breastfeeding]], [[stress (medicine)|stress]], sleep.
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| ===Prescription drugs===
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| Use of prescription drugs are the most common cause of hyperprolactinaemia. Prolactin secretion in the pituitary is normally suppressed by the brain chemical, [[dopamine]]. Drugs that block the effects of dopamine at the pituitary or deplete dopamine stores in the brain may cause the pituitary to secrete prolactin. These drugs include the major [[tranquilizers]] ([[phenothiazine]]s), [[trifluoperazine]] ([[Stelazine]]), ,and [[haloperidol]] ([[Haldol]]); some [[antipsychotic]] medications; [[metoclopramide]] ([[Reglan]]), used to treat [[Gastroesophageal reflux disease|gastroesophageal reflux]] and the nausea caused by certain cancer drugs; and less often, [[methyldopa|alpha-methyldopa]] and [[reserpine]], used to control [[hypertension]]. Finally [[Estrogen|oestrogens]] and [[thyrotropin-releasing hormone|TRH]].
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| ===Diseases===
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| Prolactinoma or other tumors arising in or near the pituitary—such as those that cause [[acromegaly]] or [[Cushing's syndrome]]—may block the flow of dopamine from the brain to the prolactin-secreting cells, likewise division of the [[pituitary stalk]] or hypothalamic disease. Other causes include [[chronic renal failure]], [[hypothyroidism]] and [[sarcoidosis]]. Some women with [[polycystic ovary syndrome]] may have mildly elevated prolactin levels.
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| Apart from diagnosing hyperprolactinaemia and [[hypopituitarism]], prolactin levels are often determined by physicians in patients who have suffered a [[seizure]], when there is doubt whether this was an [[epileptic seizure]] or a [[non-epileptic seizure]]. Shortly after epileptic seizures, prolactin levels often rise, while they are normal in non-epileptic seizures.
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| ===Idiopathic===
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| In many patients elevated levels remain unexplained and may represent a form of hypothalamic-pituitary dysregulation.
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| ==Symptoms==
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| In women, a high blood level of prolactin often causes [[hypoestrogenism]] with anovulatory [[infertility]] and a decrease in [[menstruation]]. In some women, menstruation may disappear altogether ([[amenorrhea]]). In others, mensturation may become irregular or menstrual flow may change. Women who are not pregnant or nursing may begin producing [[breast milk]]. Some women may experience a loss of [[libido]] (interest in sex). [[Intercourse]] may become painful because of vaginal dryness.
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| In men, the most common symptoms of prolactinoma are [[impotence]], decreased [[libido]], [[erectile dysfunction]], and [[infertility]]. Because men have no reliable indicator such as [[menstruation]] to signal a problem, many men with hyperprolactinemia being caused by an adenoma may delay going to the doctor until they have [[headaches]] or eye problems caused by the enlarged pituitary pressing against nearby eye nerves. They may not recognize a gradual loss of sexual function or [[libido]]. Only after treatment do some men realize they had a problem with sexual function.
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| Because of hypoestrogenism, hyperprolactinaemia can lead to [[osteoporosis]].
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| ==Diagnosis==
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| A doctor will test for prolactin blood levels in women with unexplained milk secretion ([[galactorrhea]]) or irregular [[menses]] or [[infertility]], and in men with impaired sexual function and, in rare cases, milk secretion. If prolactin is high, a doctor will test [[thyroid]] function and ask first about other conditions and medications known to raise prolactin secretion. Whilst a plain [[X-ray]] of the bones surrounding the pituitary may reveal the presence of a large macro-adenoma, the small micro-adenoma will not be apparent. Magnetic resonance imaging ([[MRI]]) is the most sensitive test for detecting pituitary tumors and determining their size. [[MRI]] scans may be repeated periodically to assess tumor progression and the effects of therapy. [[Computed Tomography]] (CT scan) also gives an image of the pituitary, but it is less sensitive than the MRI.
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| In addition to assessing the size of the pituitary tumor, doctors also look for damage to surrounding tissues, and perform tests to assess whether production of other pituitary hormones is normal. Depending on the size of the tumor, the doctor may request an eye exam with measurement of visual fields.
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| ==Historical eponyms== | | ==Historical eponyms== |