Prolactinoma (pituitary tumor)

What is a prolactinoma?

The pituitary gland is about the size of a cherry stone and is located within a bony structure at the base of the skull. There is a so-called anterior and posterior lobe of the pituitary gland and the pituitary stalk. The pituitary gland is connected to the diencephalon (hypothalamus) via this. The pituitary gland is the body’s hormone center.

Like all other cells in the body, the cells of the pituitary gland can sometimes degenerate. They then multiply uncontrollably and a pituitary tumor develops. A so-called prolactinoma is a benign tumor of the anterior lobe of the pituitary gland (pituitary adenoma) that produces the hormone prolactin in an uncontrolled manner. This can lead to an excess of prolactin in the body (hyperprolactinemia), which results in various symptoms.

Prolactinoma – frequency and age

Prolactinoma is the most common hormone-producing pituitary tumor. The disease is most common between the ages of 20 and 40. Both men and women can develop a prolactinoma. However, women are five times more likely to be affected than men.

Prolactinoma: causes and risk factors

A prolactinoma develops when the genetic material of the prolactin-producing cells of the pituitary gland changes or is misread. As a result, the cells grow or divide uncontrollably and form new tissue. As this tissue consists exclusively of prolactin-producing cells, the prolactin level in the body rises above the normal level.

Why a prolactinoma develops is not yet fully understood. In rare cases, this is due to a hereditary disease. In multiple endocrine neoplasia (MEN) type 1, around 20 percent of those affected develop a prolactinoma during the course of their illness.

Symptoms: Sexual function is often impaired

If the prolactinoma is very small, there may be no symptoms at all. In general, however, a hypopituitarism can cause symptoms in two different ways:

• Depending on the size and location of the tissue growth, neighboring areas of the brain may be affected. This can lead to visual disturbances or headaches. If the prolactinoma is very large, it can also press directly on the pituitary gland and impair its function. One consequence of this is a dysfunction of the adrenal gland or the thyroid gland.
• In addition, the excessive production of prolactin influences the effect of other hormones in the body. This causes different symptoms in men and women. Sexual dysfunction in particular is a common problem.

Symptoms in women

Prolactin has an important function for female reproduction. In pregnant women, it ensures that the mammary glands develop and that milk is produced for the newborn after birth. In women with a prolactinoma, the high prolactin level can therefore cause milk or secretions to leak from the nipple even without pregnancy or outside of breastfeeding. In addition, menstruation can be irregular or stop completely, as prolactin leads to a lack of oestrogen and inhibits ovulation. Some affected women have difficulties getting pregnant as a result. Other consequences of hormone imbalance can include, for example

• Hot flushes,
• Vaginal dryness,
• lack of desire for sex and
• bone loss (osteoporosis).

Symptoms in men

In men, a prolactinoma means that the testicles no longer produce enough sperm and testosterone. The affected man may not only lose the desire to have sex, but also become impotent and infertile. Sometimes the male mammary gland tissue increases due to the increased prolactin level and the breast enlarges, sometimes milk leaks from the nipples. However, this is rarely the case.

Prolactinoma: Diagnosis at the USZ

In order to diagnose a prolactinoma, we will first take your medical history (anamnesis). We ask you various questions such as:

• What complaints do you have?
• How long have these complaints been present?
• Are you pregnant?
• Do you suffer from another illness?
• Do you take any medication? If so, which ones?

After a detailed discussion with you, a physical examination will follow. We are particularly interested in the following:

• Has the breast enlarged or is secretion leaking from the nipple?
• Are there any visual disturbances, especially loss of the visual field, problems with color vision or visual acuity?
• Are there signs of an underactive thyroid such as hair loss, dry skin, an enlarged thyroid gland or similar?
• In men: Are there signs of a testosterone deficiency?
• In women: Are there signs of estrogen deficiency?

Blood test shows prolactin levels

If a prolactinoma is suspected, it is important to measure the prolactin level in the blood. To do this, we take a blood sample, which is later analyzed in the laboratory.

Imaging procedures can confirm the suspicion

To confirm the suspicion of a prolactinoma, we carry out a magnetic resonance imaging (MRI) scan after an abnormal blood test. With this imaging procedure, we can usually visualize the pituitary tumour and also assess its location and size. Only in the case of very small prolactinomas is it sometimes difficult to visualize them.

Exclude other causes

An important task in the diagnosis of a prolactinoma is to rule out other causes of an elevated prolactin level. Other triggers for hyperprolactinemia are, for example

• certain medications (e.g. for the treatment of mental illnesses),
• Stress,
• other diseases (e.g. renal insufficiency, hypothyroidism),
• other tumors that affect the connection between the pituitary gland and the hypothalamus or

very rare accidents in which the pituitary gland is damaged.

Prolactinoma: prevention, early detection, prognosis

As a prolactinoma often leads to menstrual cycle disorders, it is usually detected earlier in women than in men. Beyond that, however, there are no signs that make early detection possible. Experts have also not yet been able to fully explain the causes of prolactinoma. There are therefore no direct measures that can prevent the development of prolactinoma. However, you can strengthen your health and immune system by maintaining a healthy lifestyle.

Progression and prognosis (prolactinoma)

Despite successful treatment, a prolactinoma can sometimes recur (recurrence). Various undesirable side effects are also possible as a result of the treatment. This can lead to hypofunction of the pituitary gland after surgery or radiotherapy, which makes hormone replacement therapy necessary.

However, as a prolactinoma usually grows slowly and normally responds well to treatment, the disease often progresses well. In the case of small prolactinomas in particular, both drug therapy and the sometimes necessary surgical treatment are usually successful.

Self-help groups

The exchange with people who are affected by the same disease can be a great support in coping with the disease. Advice on finding a suitable self-help group is available from Selbsthilfe Zürich. Self-Help Zurich and the University Hospital Zurich are cooperation partners in the national project “Health literacy thanks to self-help-friendly hospitals”.

Prolactinoma: treatment is not always necessary

If the prolactinoma is very small and does not cause any symptoms, there is usually no treatment. However, we regularly check whether the tissue overgrowth is changing or growing strongly. However, if symptoms occur, there are various treatment options available.