Prolactinoma: Symptoms, Causes and Treatment

Prolactinoma is a benign tumor of pituitary gland which is non-cancerous and produces large quantity of hormone known as prolactin. High blood level of this hormone is known as hyperprolactinemia. Symptoms arise due to the mass effect of the pituitary tumor as well as the hyperprolactinemia. Prolactinomas are the most common type of hormone producing tumor of the pituitary gland. It can cause infertility, impair your vision and much more. Depending upon the size there are known as macroprolactinoma or microprolactinoma. According to the population studies, the prevalence of prolactinoma is estimated to be approximately 10 per 100,000 in men and 30 per 100,000 women

Symptoms of Prolactinoma

The signs and symptoms arise when the enlarging tumor starts compressing the adjacent structures or due to high level of prolactin in the blood

Due to hyperprolactinemia: Elevated levels of prolactin hormones causes the levels of sex hormones to reduce in the blood and this can disrupt the functioning of the gonads leading to the hypogonadism, therefore some signs and symptoms are specific to the male and females

For females these includes

• Irregular periods or absence of menstruation
• Excessive growth of body and facial hairs
• Painful intercourse due to dryness of vaginal mucosa (inner lining)

For males these includes

• Decreased facial and body hairs
• Erectile dysfunction
• Increase in the size of the breast known as gynecomastia

For both males and females

• Decreased sex drive
• Decrease in the density of the bones
• Infertility
• Due to the mass effect of the tumor
• Reduction in other hormones of the pituitary and their specific signs and symptoms due to the compression of the normal mass of the pituitary
• Visual disturbances
• Recurrent headaches

Complications of Prolactinoma

If left untreated then the following can be the complications of the prolactinoma

Complete blindness: this is due to the compression of the optic nerve

Osteoporosis: This is due to very low levels of sex hormones that results in loss of calcium from the bones. The density of the bones decreases so much that fractures can occur.

Diagnosis of Prolactinoma

Your doctor will use your medical history as well as run some tests to reach a diagnosis

Medical history: your doctor will ask you detailed questions

• About your signs and symptoms
• About your current and past medications
• About your previous illnesses
• About your previous treatments

If the signs and symptoms of hyperprolactinemia are present, then it is not certain that you have prolactinoma because there are other reasons that can cause hyperprolactinemia. So, your doctor need to rule out these other possible causes like medications, pregnancy or any other condition

Laboratory tests

• Blood tests: A small sample of blood is taken to check for the levels of prolactin hormone. Very high level of hormone is suggestive of prolactinoma. Pregnancy tests should be also done in the women of child bearing age. Levels of other hormones can be measured like thyroid or other pituitary hormones because their levels get also affected due to the compression of the pituitary.
• Imaging tests: MRI is the most sensitive imaging test to detect the pituitary tumors and to assess their growth. It will also help your doctor to look for the damage to the other surroundings
• Vision test: It can be done by an ophthalmologist to look for any defects in the vision. This is usually a late complication

Treatment of Prolactinoma

The goals of the treatment are to reduce signs and symptoms by reducing the levels of prolactin secretion to the normal, reducing the tumor size, correcting any visual defects and restoring the normal functioning of pituitary. So, treatment consists of medications and surgery

Medications: these can be used to lower the hormone level and to shrink the size of the tumor but long-term treatment is required. Dopamine is a natural chemical in the brain that inhibits the production of the hormone. So, your doctor can prescribe you dopamine agonists like bromocriptine(Parlodel) or cabergoline(Dostinex).

There are known side effects of these medications and it is necessary to discuss these with your doctor and don’t stop the treatment on your own and without consulting with your doctor.

Surgery: If the medication therapy is not sufficient to control the prolactin levels, not reducing the size of tumor such that it is compressing the optic nerve causing defects in the vision or the patient is not able to tolerate the medicine, then surgery can be considered but it is never a first choice

Most often the tumor size is small and it is removed through nose but large tumors are removed through an opening in the skull.

Radiation: When both the medication and surgery is not beneficial for the patient, then radiation therapy can be considered.

Prognosis of Prolactinoma

Patients who have microprolactinoma have an excellent prognosis as 95% of these patients respond well to the medication and their tumor don’t increase in the size over a period of 4-6 years but patients suffering from macroprolactinoma don’t have prognosis as good as above requires aggressive treatment and careful monitoring.

Resources:

Prolactinoma. National Institute of Diabetes and Digestive and Kidney Diseases

The American Association of Clinical Endocrinologists

Endocrine society

Kasper DL, et al., eds. Anterior pituitary tumor syndromes. In: Harrison’s Principles of Internal Medicine. 19th ed. New York, N.Y.: McGraw-Hill Education; 2015