Causes
Increases in prolactin levels (hyperprolactinemia) may occur:
For physiological reasons: pregnancy, puerperium, stress, exercise, sleep, protein-rich meals, breastfeeding, sexual activity;
For the use of some drugs : tricyclic antidepressants, antiepileptics, antihypertensives, antiemetics (against nausea and vomiting), antihistamines, cocaine, sometimes birth control pills, metoclopramide-sulpiride, veralipride;
Unknown causes ( idiopathic );
Pathological causes: adenoma of the pituitary gland (benign tumor secreting prolactin, also called prolactinoma), non-secreting pituitary adenomas, acromegaly, empty saddle syndrome, Cushing, meningiomas (malignant tumors of the meninges), dysgerminoma (testicular cancer), others tumors, sarcoidosis;
Neurological causes: lesions of the chest wall due to herpes zoster, spinal cord injury;
Other causes of hyperprolactinemia: hypothyroidism, kidney failure, liver cirrhosis, insufficiency of the adrenal gland.
Consequences
Hyperprolactinemia causes various alterations in reproductive function, up to the lack of ovulation in women. This is because the hypothalamic-pituitary-ovarian axis is also sensitive to small elevations in circulating prolactin levels. In fact, an altered prolactin secretion is very often associated with amenorrhea (lack of menstruation) or other menstrual disorders. It is estimated that about 15-30% of secondary amenorrhea, ie not due to ovarian disorders, is due to hyperprolactinemia. Hyperprolactinemic amenorrhea is characterized by the elevation of prolactin levels with a value greater than 25 nanograms per milliliter, visible with a simple blood test. In about 30-50% of cases, hyperprolactinemic amenorrhea is accompanied by galactorrhea, that is, the spontaneous release from the nipple of a milky secretion outside the period of breastfeeding. In this case, there will be the so-called galactic amenorrhea syndrome .
In 50% of the cases the amenorrhea is preceded by menstrual irregularities of various types, such as oligomenorrhea (retarding cycles), hypomenorrhea (poor menstruation), menoraggias (menstruation too long), metroraggie (intermenstrual blood loss, generally post-ovulatory, also called spotting). Other rarer symptoms related to hyperprolactinemia are headache and visual disturbances when the tumor expands.
Prolactant pituitary adenomas
They deserve a separate discussion with respect to all the other causes of hyperprolactinemia, since they are the most common benign tumors (ie producing prolactin) more frequent than the pituitary. They represent 60-70% of all pituitary adenomas. Typically these tumors are discovered in women of reproductive age who present more or less suddenly menstrual disorders related to a situation characterized by an increase in circulating prolactin levels. The evolution of these tumors is usually slow and gradual, but in isolated cases a rapid increase in their size is also possible. Most of them are microprolactinomas, which are smaller than 10 millimeters in diameter. They, untreated, seem to progress towards a progressive reduction over time, or at least tend to remain stable. Furthermore, they frequently undergo partial spontaneous necrosis (destruction). The age distribution in which they can occur varies from 2 to 84 years, with a peak incidence around 60 years. The frequency between the two sexes is similar; however, clinical manifestations, especially alterations in reproductive function, are more frequent in women.
Diagnosis
From the diagnostic point of view, the main problem consists in the differentiation of tumor hyperprolactinemias from non-tumor ( functional ) ones. Today it is fairly agreed that there is no net limit between these two forms, both because some particularly small microadenomas can escape the current means of investigation, and because it is possible for hyperstimulated pituitary cells to pass through different stages of activity, from simple hyperfunction to hyperplasia (multiplication) to producing franc adenomas (uncontrolled multiplication), more or less tending to the compression of the surrounding tissues.
In all cases in which the existence of an alteration in the production of prolactin is suspected (amenorrhea, with or without galactorrhea; failure to ovulate; intermenstrual spotting, etc.) it is first necessary to dose the plasma prolactin with a simple blood test. Once it has ascertained its high value, more dosages must be performed (two or three) over the course of 24 hours and for several days, in order to eliminate errors linked to variations during the day and withdrawal stress. An alternative and more practical method, similar to the previous one, can be that of the three dosages to be carried out within an hour and a half, one at a distance of half an hour from the other, interspersed with the administration of a physiological solution through an infusion.
In the presence of persistently high values, higher than 60 nanograms on milliliter, in all three derivations, after excluding with the plasma dosage of thyroid hormones T3 and T4 and TSH the existence of a hypothyroidism, we will move towards an adenoma pituitary; therefore a CT (computed tomography) or a TMR (magnetic resonance tomography) with contrast agent of the sellaturcica will be performed, which is the anatomical structure at the base of the skull in which the pituitary gland is contained. They allow us to appreciate the presence of microadenomas and adenomas of the pituitary gland and their possible extension to the surrounding structures, especially to the optic chiasm, a structure formed by the nerve extensions of the optic nerve which is found to pass immediately above the saddle. If the tumor compresses the chiasm, the patient could have visual field disorders that, even if asymptomatic, can be highlighted with an exam called campimetry, generally complementary to CT and TMR . Above all it allows to evaluate the possible expansion of the tumor; therefore, while it does not seem absolutely necessary in the presence of a microadenoma, it is extremely useful and necessary in the surveillance of the evolution of macroadenomas.
