Prolactin. Hyperprolactinemia

What is?

The hormone prolactin is the hormone responsible for stimulating the secretion of breast milk. Prolactin is secreted almost exclusively by cells which are called lactotrope, found in the anterior pituitary gland in the brain. These cells are subject to the inhibitory effect of a substance called dopamine producing brain hypothalamus, so that when more dopamine is released and vice versa least prolactin secreted.

Is impaired by excess production and secretion of this hormone, termed hyperprolactinemia, defined as an increase in most blood prolactin (PRL) (in women of 20 ng / mL in males and greater than 16 ng / mL).

Women of childbearing age (premenopausal)

In premenopausal women (childbearing age) symptoms of this disorder are correlated with the magnitude of hyperprolactinemia:

• If the values ​​of the age PRL 50ng / ml usually occurs: oligomenorrhea or long menstrual cycles (> 45-60 days), amenorrhea or absence of menstruation, galactorrhea or milk nipple discharge (it is shown only in 30-40 % of cases), infertility, hot flashes, vaginal dryness and osteopenia or amenorrhea or absence of menstruation, galactorrhea or milk nipple discharge (shown only in 30-40% of cases), infertility, hot flashes, vaginal dryness and osteopenia or osteoporosis .
• If PRL values ​​are between 20 and 50 ng / ml insufficient production of progesterone cause a short luteal phase or proiomenorreas (short menstrual cycles, around 21-24 days), and infertility appear, even though there are no abnormalities in the menstrual cycle .

Postmenopausal women

In postmenopausal women, hyperprolactinemia is recognized only in rare cases where it appears as a result of macroprolactinoma (large tumor prolactin-secreting cells) that manifests with headaches or vision defects by mass effect of the tumor on cerebral nerve structures next.

Men

In men, hyperprolactinemia occurs with decreased libido or sexual desire , erectile dysfunction or impotence, infertility, decreased muscle mass, osteoporosis, headaches and possible visual anomalies.

What are the symptoms of hyperprolactinemia?

Increased prolactin in blood causes inhibition of the production of a hypothalamic hormone (gonadotropin releasing hormone) which is responsible for stimulating the production of sex hormones called two -hormona gonadotropins follicle stimulating hormone (FSH) and luteinizing hormone (LH) - . These hormones act on the ovary favoring the synthesis of female sex hormones (estrogen) and ovulation. So when prolactin increases and inhibited thereby secretion releasing hormone gonadotropin, having less FSH and LH lack of ovulation, estrogen decline and consequent menstrual disorders (amenorrhea or lack of menstruation occurs mainly ).

Then we analyze the different symptoms or manifestations that occur in women during their childbearing age, postmenopausal women with men.

1. Physiological causes

• Pregnancy: PRL levels in maternal blood increase during pregnancy, peaking at the time of delivery . Six weeks after birth, the hormone levels return to normal, even if the mother continues breastfeeding her child.
• Nipple stimulation: during the feeding , the suction nipple causes a reflection by which peaks occur in prolactin secretion. As time goes by these peaks they are becoming less intense.
• Stress: any type of stress , physical or emotional, can produce hyperprolactinemia, although in this case the hormone figures rarely exceed 40 ng / ml.
• Sleep and sex: can also be accompanied by a rise in the levels of this hormone.

2. Pathological Causes

• Drugs. Many drugs can cause elevations in the concentrations of PRL, some fairly common use. They are the most common cause of hyperprolactinemia, generally have a blocking effect on dopamine (by decreasing dopamine, which inhibits secretion of prolactin, indirectly favor increased prolactin secretion). The most prominent are: Antipsychotic drugs: phenothiazines, risperidone, haloperidol. Antidepressants: clomipramine. Use of gastrointestinal drugs: ranitidine, cimetidine, metoclopramide (Reglan), sulpiride (Dogmatil). Antihypertensive drugs methyldopa, verapamil. Antitussives: codeine. Narcotics: morphine, methadone. Estrogen, although it should be clear that the amount of estrogen Oral contraceptives do not cause hyperprolactinemia.

Under what circumstances prolactin production increases?

The increase in prolactin production may be due to physiological causes and pathological causes.

In a significant number of patients is not detectable cause to justify increased prolactin, despite performing all diagnostic tests available; It is what is called "idiopathic hyperprolactinemia". In these cases blood levels of this hormone range between 20ng / ml and 100ng / ml. It is thought that most of these patients would be so small microadenomas not visible in brain imaging.

How is it diagnosed?

Any woman who has menstrual disorders or galactorrhea owed systematically make a determination of prolactin in blood. This hormonal determination is also part of the study of infertility. Of course, if a man or a postmenopausal woman consulting for the above symptoms will also be given the blood test of this hormone, but these circumstances are rare.

Should you get a value of 20 ng / mL and 40 ng / mL should be repeated blood tests before considering that the patient has or hyperprolactinemia. After a definitive diagnosis is required to study the cause of it by performing a detailed medical history, ruling out taking drugs that cause hyperprolactinemia, hypothyroidism symptoms and history of renal and liver failure.

The physical examination should also rule out abnormalities of the visual field. In case of suspicion of hypothyroidism the determination of thyroid hormones is required. If there is an obvious cause, you must perform a nuclear magnetic resonance (NMR) of the hypothalamic-pituitary region of the brain to rule out a tumor. Failure to find any known cause, will diagnose the patient with idiopathic hyperprolactinemia.

What is the treatment?

The goals of treatment are:

The treatment of choice for hyperprolactinemia of any cause, except secondary to drugs, regardless of the size of the pituitary tumor (if any) is using drugs called dopamine agonists. Cabergoline (Dostinex) is currently recommended because their administration is simpler (1-2 times per week) and has fewer side effects.

Bromocriptine (Parlodel) is the drug that was first used to treat this disease. It is an alternative in the case of no response to cabergoline. It is also recommended as a first choice in women wishing to become pregnant because there are more evidence that this drug does not cause birth defects (however, the suspension of treatment is recommended once the patient knows she is pregnant).

These drugs have side effects such as nausea, vomiting, headaches, postural hypotension (low blood pressure with changes of position), dizziness and nasal congestion, but these effects can be minimized by increasing the dose progressively or by administering intravaginal drug also effective.

If the figures of prolactin can not normalize with medical treatment or it is not tolerated because of their side effects may resort to surgical treatment by tumor resection by transsphenoidal, ie through the frontal region -nasal.

After two years of treatment with normal levels of prolactin and the disappearance of the tumor in the MRI, it can raise its suspension but would have to perform periodic testing of prolactin figures should they be returned to increase.

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• Normalize prolactin levels and restore ovarian function.
• For large pituitary tumors, reduce tumor size to reverse the symptoms caused by compression of the tumor.