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The prolactin tumor is the most common hormonally active pituitary tumor both in the general population and during pregnancy. The causes of the ailments are believed to be the low level of dopamine responsible for inhibiting the secretion of prolactin. Symptoms accompanying the disease are amenorrhea and infertility.
What is a prolactin tumor?
A prolactin tumor (prolactinoma) is an adenoma that is made up of the elements that make up the pituitary gland. It secretes a very large amount of prolactin. As a result, the level of prolactin in the body increases and the condition known as hyperprolactinemia develops. A prolactin tumor can range in size from small, a few millimeters, to large, more than four centimeters in size. Taking into account the size of the tumor, the following can be distinguished:
- microadenomas (their size does not exceed 1 cm),
- macroadenomas (their diameter is greater than 1 cm).
What is prolactin?
Prolactin is a hormone that is produced, among others, in adipose tissue, hair follicles or the pituitary gland. The task of prolactin is to stimulate the mammary glands to produce milk after delivery. In addition, this hormone significantly affects the functioning of the gonads and adrenal glands and stimulates our immune system. Excess prolactin in the body has a negative effect, e.g. on the work of the ovaries.
Why does a prolactin tumor arise?
The causes of this ailment are not fully known. However, some importance is attached to the reduction of dopamine levels in the body, the task of which is to inhibit the secretion of prolactin. Genetic predisposition is also taken into account.
The factors increasing the level of prolactin in the blood include:
- stress,
- pregnancy,
- breast-feeding
- Hypothyroidism,
- the use of certain preparations, e.g. estrogens or psychotropic drugs,
- liver and kidney failure.
Prolactin tumor – symptoms
The symptoms vary depending on the size of the tumor. Visual acuity disturbances and headaches may occur in patients with macroadenoma.
The main symptoms of a prolactin tumor are secondary amenorrhea (irregular periods, scanty or heavy) and infertility, but effective pharmacological treatment with dopaminergic agonists such as bromocriptine and cabergoline restores ovarian function and enables pregnancy. Some people also experience pain during sexual intercourse. Women with excess prolactin complain of galactorrhoea, which is the production of milk in the mammary glands unrelated to lactation (amenorrhoea-galactorrhoea syndrome). On the other hand, pregnancy – due to the physiological state of hyperestrogenism – increases the risk of further enlargement of the prolactin tumor with subsequent clinical symptoms, such as:
- the appearance or intensification of visual field disturbances,
- headaches,
- the onset of diabetes insipidus symptoms.
A prolactin tumor that reaches a size less than 1 cm is also manifested by visual disturbances, but also by a lower secretion of gonadotropin by the pituitary gland.
High levels of prolactin in the male sex can cause a decrease in libido, infertility, impotence and a decrease in muscle mass. In addition, in men, a prolactin tumor may cause hair loss in the intimate area and on the face. There are also cases of gynecomastia, i.e. enlargement of the mammary glands.
In addition to the above-mentioned symptoms, a prolactin tumor also negatively affects the skeletal system.
The general symptoms that occur in both women and men are:
- headache,
- decrease in bone density,
- symptoms indicating paralysis of the cranial nerves in the area of the pituitary gland,
- narrow field of view.
Diagnostics of a prolactin tumor
Pregnant women
It is practically unlikely that hyperprolactinaemia caused by a prolactin tumor begins during pregnancy. Hence, we cannot speak of a pregnancy-specific diagnosis of a prolactin tumor. However, it is very important to monitor pregnant patients with diagnosed (and treated) prolactin tumors prior to pregnancy, including regular ophthalmological consultations with visual field assessment, determination of prolactin levels and, possibly, magnetic resonance imaging (MRI) without contrast, especially in the case of suspected tumor enlargement . Although the determination of prolactin concentration is of mediocre diagnostic value during pregnancy, due to the non-invasiveness of this test, it should not be abandoned. It is important that under physiological conditions, despite a significantly increased concentration of prolactin, an increase in its secretion at night is observed.
Performing a radiological examination is prohibited. Systematic observation of pregnant women with a prolactin tumor is sometimes necessary due to the necessity of surgical intervention (in the second trimester of pregnancy). However, such monitoring in the postpartum period is of less importance as breastfeeding is not usually associated with the risk of prolactin tumor enlargement.
Other patients
The basis of the diagnosis of a prolactin tumor is the assessment of characteristic symptoms and the performance of laboratory tests. The test should be performed several times in order to minimize the impact of stress resulting from blood collection. As you know, stress is one of the factors that increase the level of prolactin in the blood. If the prolactin level is greater than 400 ng / ml, no further testing is necessary.
The concentration of prolactin in the blood below 200 ng / m means that the patient has microadenoma, while the concentration above 200 ng / ml means that we are dealing with the presence of macroadenoma. When in doubt, execute functional testduring which the patient is given an oral or intravenous antiemetic. In healthy people, the applied preparation will cause the level of prolactin to increase up to three times, while in people with a prolactin tumor, we do not notice such an effect.
In addition, diagnostic doubts can be dispelled by magnetic resonance imaging with contrast, which allows to identify the presence of a prolactin tumor and to assess the degree of its pressure and invasion of the surrounding structures. Unfortunately, this study does not make it possible to say whether the tumor is hormonally active.
If a large-size prolactin tumor is diagnosed, patients are referred for ophthalmological examination. During the consultation, the patient’s field of view is checked.
Remember! A prolactin tumor can sometimes compress the healthy part of the pituitary gland, which in turn leads to its failure and disturbances in the secretion of other tropic hormones. So, if you have been diagnosed with a large tumor, ask for a referral for tests to assess the secretory function of the pituitary gland.
How to treat a prolactin tumor?
Treatment of a prolactin tumor is primarily aimed at: preventing the tumor from growing; lowering the concentration of prolactin; tumor reduction; improving the quality of life of a patient with a tumor and maintaining other functions of the pituitary gland.
Pharmacological treatment introduces preparations that stimulate the growth of dopamine concentration, which is responsible for lowering the level of prolactin. Such drugs are, for example: cabergoline, bromocriptine and quinagolides. Unfortunately, these preparations may cause side effects in the form of pressure reduction during upright standing and gastrointestinal disorders. For this reason, these drugs should be started at low doses.
The diameter of the prolactin tumor decreases after only a few days of treatment, although for full remission of the disease, therapy should last up to several years. Usually, drug withdrawal is attempted when prolactin levels remain within the normal range after three years. However, patients still need to monitor its blood levels. It should be remembered that stopping the medication too early may not only cause the disease to come back, but also increase the tumor mass. Pregnant women may also take dopamine agonists.
On the other hand, surgical treatment of a prolactin tumor is used in people who do not respond to pharmacological treatment or are allergic to the prescribed preparations. Surgery is especially necessary when a prolactin tumor is causing visual disturbances. Unfortunately, in the case of large tumors, the effects of the procedure are not always satisfactory, because recurrences often occur (50% of tumors with a diameter greater than 1 cm). Surgery is usually performed through the nose and is most effective in microadenomas.
What’s the prognosis?
Most microadenomas rarely develop into macroadenomas (the probability is 5-10%). On the other hand, in every third woman the prolactin tumor is a self-limiting ailment. Women with tumors who become pregnant at that time have a much higher remission rate than others. The normalization of the prolactin function of the pituitary gland also occurs during the menopause. Rarely, prolactin normalizes in people taking medication erratically or receiving no treatment at all.
Source: A. Cajdler-Łuba, S. Mikosiński, A. Sobieszczańska-Jabłońska, I. Nadel, I. Salata, A. Lewiński: “FUNCTIONAL DIAGNOSTICS OF HORMONAL DISORDERS WITH ELEMENTS OF DIFFERENTIAL DIAGNOSTICS; Czelej Publishing House