Prolactinoma - Types, Causes, Symptoms, Complications, Diagnosis, and Treatment

What Is a Prolactinoma?

The pituitary gland is a small pea-sized gland located in the skull base. It produces hormones for normal body functioning. A prolactinoma is a harmless growth occurring in the pituitary that stimulates excess production of prolactin. Symptoms occur when excessive amounts of prolactin are secreted into the bloodstream.

What Is Prolactin?

Prolactin is a hormone secreted by the pituitary gland that helps develop mammary gland and breast milk production. Prolactin levels are high in pregnant and lactating mothers. However, they are low in males, non-pregnant, and non-breastfeeding females. An excessive increase in the prolactin blood levels can indicate a tumor in the pituitary.

What Are the Types of Prolactinomas?

Based on the size, prolactinomas are classified as:

1) Microprolactinomas:

• They are smaller than 10 mm in size.

• More commonly noticed in girls.

• Present at birth.

2) Macroprolactinomas:

• They are larger than 10 mm in size.

• More commonly noted in males.

• Present at older ages.

What Are the Causes of Prolactinoma?

The exact cause of prolactinoma remains unknown. However, there is an increased tendency of occurrence in people with an inherited condition called Multiple endocrine neoplasia (MEN) type 1. MEN type 1 is a rare, inherited disorder that causes harmless tumors in the parathyroids, pituitary glands, and pancreas that leads to a release of excessive hormones causing symptoms.

How Commonly Do Prolactinomas Occur?

Prolactinomas account for about 40 % of all brain tumors, making them the most common type. Females are at greater risk when compared to males. Children are rarely affected.

What Are the Symptoms of Prolactinomas?

The symptoms of prolactinomas depend upon various factors like the amount of excess prolactin secreted into the bloodstream or pressure on the surrounding structures. Some signs are noted in females and others in males. However, both the sexes may present common symptoms.

Symptoms in Females:

• Irregular or no menstrual cycle.

• Milky white discharge in non-pregnant and non-lactating females.

• Loss of sexual interest.

• Discomfort or pain during sex due to dry vagina.

• Increase in body and facial hair.

• Oily skin along with acne.

Symptoms in Males:

• Erectile dysfunction due to which there is an inability to get or keep the penis straight for sexual activity.

• Loss of interest in sex due to low levels of testosterone.

• Infertility.

• Enlargement of breasts.

• Milky white discharge from the nipples occurs rarely.

• Decrease in body hair.

Symptoms Noted in Both Sexes:

• Decrease in bone density.

• Headaches.

• Visual disturbances or loss of vision.

• Pressure or pain in the sinus area.

• Nausea and vomiting.

• Difficulty in perceiving smells.

Females tend to observe the symptoms earlier than males, like milky discharge from the nipples or irregular menstrual cycle, when not pregnant or lactating. Males and females who have attained menopause develop symptoms only after the prolactinoma has grown to a large size, causing pressure on the surrounding structures.

What Are the Complications Associated With Prolactinomas?

The following complications are noted in patients with prolactinomas:

1. Problems in Pregnancy: The estrogen levels rise during pregnancy; however, prolactinomas cause a decrease in estrogen levels. This imbalance leads to complications in pregnancy. Therefore, if the patient with prolactinoma is planning pregnancy, necessary treatment and subsequent monitoring of the hormonal levels is suggested to prevent untoward complications.

2. Weak Bones: Increased levels of prolactin can cause a decrease in estrogen and testosterone levels that leads to weakening of bones leading to osteoporosis.

3. Loss of Vision: Prolactinomas that grow big can lead to compression of the optic nerve, leading to problems with vision.

4. Effects on Other Pituitary Hormones: Large prolactinomas cause pressure on the pituitary gland, which leads to a decrease in the average hormone production by the gland. The release of hormones like thyroid-stimulating hormone (TSH) and cortisol are affected.

How Are Prolactinomas Diagnosed?

Diagnosis is based on the determination of hormonal blood levels and a brain scan to know the size and location of the prolactinoma. The doctor suggests the following tests:

• Blood Tests: Higher than normal prolactin levels in the blood aid in the diagnosis of prolactinoma. The doctor may suggest further imaging tests to confirm the diagnosis.

• Magnetic Resonance Imaging (MRI) Scans: MRI scan is the most commonly employed technique to confirm prolactinomas. They help detect the location and the size of the tumors.

• Computed Tomography (CT): CT scans are recommended in cases where the patient has a metal implant or a pacemaker in the body and cannot go for an MRI scan. CT scans help establish the diagnosis and confirm the location and size of the tumor.

• Testosterone Levels: In male patients, the doctors suggest a blood test to determine their testosterone levels. A low testosterone level is used to diagnose a prolactinoma.

• Vision Tests: Vision tests are indicated in patients with large prolactinomas that may cause pressure on the optic nerve, leading to vision problems.

• Bone X-Rays: X-rays of the spine and hip bones are advised to check for any bone thinning or osteoporosis due to increased prolactin and decreased estrogen levels in the blood.

What Are the Treatment Plans for Prolactinomas?

Prolactinomas are treatable with medications. Surgery and radiotherapy are suggested rarely.

The aims of the treatment include:

1. Shrinking the size of the tumor.

2. Bringing back the prolactin blood levels to normal.

3. Reducing the damaging effects on the pituitary.

4. Restoring the functions of other pituitary hormones.

5. Improving the quality of life.

Treatment options for prolactinomas include:

Medication:

• Medicines called Dopamine agonists are used to control the prolactin levels in the blood. They also help to shrink the size of tumors, thereby reducing the effects of pressure on the surrounding tissues and nerves.

• Cabergoline, Bromocriptine, and Quinagolide are the commonly used medications.

• Common side effects of these medicines include dizziness, nausea, and vomiting.

• The doctor prescribes medications for two years. Treatment is started with a low dosage, and once the patient's body gets accustomed to the medicines, the dosage is gradually increased.

• Fertility is restored once the treatment is started. However, the patient is asked to avoid the medication during pregnancy, and regular monitoring of the prolactin levels is recommended.

Surgery:

• Surgery is considered in cases where the patient has side effects due to medicines, drug interactions (with other drugs that the patient is using), or a giant tumor.

• The two types of surgeries that are used to treat prolactinomas include:

  • Transsphenoidal Surgery: This is the most commonly employed technique. Access to the tumor is achieved through the nasal cavity. Therefore, complications are less in the transsphenoidal approach.

  • Transcranial Surgery: Larger tumors that are difficult to remove through transsphenoidal or nasal surgery are removed by the surgeon through surgery in the upper part of the skull.

Radiation:

• Therapy with radiation is suggested in cases that do not respond to medicines or surgery. However, it is a rarely employed technique. A single dose or multiple doses of radiation are decided based on the size of the tumor and the prolactin levels in the blood.

Conclusion:

Prolactinomas are benign tumors that are not life-threatening; however, timely diagnosis and treatment help prevent complications that arise as the tumor grows. Medications heal the tumors positively, and surgery is indicated in a few cases. In addition, periodic blood tests and scans after the treatment help watch the tumor growth after therapy.