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What is prolactinoma?

Prolactinoma is a type of low-grade (non-cancerous) tumour that develops in the pituitary gland, a small gland located at the base of the brain. Prolactinomas are rare but they are the most common type of pituitary gland tumour (also known as pituitary adenoma).

Despite their proximity to the brain, prolactinomas are not brain tumours, but are considered with them as they can grow to impact on brain and cranial nerve function. Prolactinomas develop from the cells in the pituitary gland that produce the hormone prolactin. Prolactin is primarily responsible for stimulating breast milk production in women after childbirth, but it also plays a role in regulating reproductive function in both men and women.

When a prolactinoma develops, it can cause an overproduction of prolactin, leading to various symptoms, hormonal imbalances and importantly infertility.

Prolactinomas can also be called lactotroph adenomas.

What are the common symptoms of a prolactinoma?

A prolactinoma can cause the following symptoms:

  • Irregular menstrual periods or loss of menstrual periods (amenorrhea) in women
  • Milky discharge from the breasts (galactorrhea) in women, and very occasionally in men
  • Infertility or difficulty getting pregnant
  • Decreased libido (sex drive) and erectile dysfunction in men
  • Headaches, especially if the tumour grows large and increases pressure within the brain

People with prolactinomas may develop vision problems, such as blurred vision or loss of peripheral vision, if the tumour presses on the optic nerves.


What is the prognosis for someone diagnosed with prolactinoma?

The prognosis for people diagnosed with a prolactinoma is very good. Most prolactinomas are successfully treated with medication, or surgery.


What is the treatment for prolactinoma?

The choice of treatment for prolactinoma will depend on a variety of factors including size of the tumour, the health of the patient, the severity of symptoms experienced and the patient’s goals for fertility. 

Surgery is the most common treatment for pituitary tumours. A neurosurgeon will remove as much of the tumour as possible through a procedure called transphenoidal resection, where the tumour is accessed and removed through the nose. Surgery may be followed by medication to control any remaining tumour or prolactin production.

The medication for prolactinomas works by reducing the amount of prolactin the pituitary gland makes, which reduces symptoms and may also shrink the tumour. An example of the medication is cabergoline. Not all patients tolerate drug treatment well and side effects are common.

Radiation therapy is rarely used as a primary treatment for prolactinomas.  It involves using high-energy X-rays or other radiation sources to target and destroy the tumour cells.

Regular monitoring and follow-up care by an endocrine specialist are essential to assess treatment response, manage any side-effects, and ensure the best control of prolactin levels.




What is the main cause of prolactinoma?

The main cause of prolactinomas is often unknown. However, several factors may contribute to their development. These factors include hormonal imbalances, disruptions in dopamine regulation, genetic predisposition in rare cases, certain medications, and other factors like pregnancy or breastfeeding. Prolactinoma levels in the blood can vary, but significantly elevated levels, typically above 200-250 mcg/L, are often indicative of a prolactinoma.


What are the prolactinoma levels?

Prolactinoma levels refer to the measurement of prolactin hormone levels in the blood. Prolactinomas are tumours of the pituitary gland that lead to elevated prolactin levels in the body. The levels of prolactin can vary depending on the size and activity of the tumour.

Normal prolactin levels in non-pregnant, non-lactating individuals are typically less than 25 micrograms per litre (mcg/L) in women and less than 20 mcg/L in men. In individuals with prolactinomas, the prolactin levels can be significantly higher, ranging from mildly elevated to very high levels.

The specific ranges for elevated prolactin levels can vary slightly between different laboratories and testing methods. Generally, prolactin levels above 200-250 mcg/L are considered significantly elevated and often indicative of a prolactinoma. However, it's important to note that the diagnosis of a prolactinoma is not solely based on prolactin levels but also requires clinical evaluation, imaging studies (such as MRI), and assessment of symptoms.

It's worth mentioning that in some cases, slightly elevated prolactin levels can be caused by factors other than prolactinomas, such as certain medications, stress, exercise, nipple stimulation, and certain medical conditions affecting the hypothalamus or pituitary gland. Therefore, further evaluation is necessary to determine the cause of elevated prolactin levels and to confirm the presence of a prolactinoma.


What are the types of prolactinoma?

Prolactinomas are a type of pituitary tumour that overproduces the hormone prolactin. There are two main types of prolactinomas based on their size:

Microprolactinomas: These are small prolactinomas measuring less than 10mm in diameter. They are typically low-grade (non-cancerous). They often respond well to medication therapy. They are more common than macroprolactinomas.

Macroprolactinomas: These are larger prolactinomas measuring 10mm or more in diameter. Macroprolactinomas can range in size from a few centimetres to several centimetres. They may have more significant effects on hormone levels and can cause symptoms due to their size and potential compression of surrounding structures.

The classification of prolactinomas into microprolactinomas or macroprolactinomas is primarily based on their size, with a cut-off of 10mm used to differentiate between the two types. It's important to note that the size of the prolactinoma does not necessarily indicate its behaviour or potential for causing symptoms. Both microprolactinomas and macroprolactinomas can be treated effectively with medication therapy and, in some cases, surgery or radiation therapy may be considered.


Can a prolactinoma affect my ability to drive a car?

Having a prolactinoma requires the DVLA to be notified. If treated by chemotherapy or transphenoidal surgery driving can resume on recovery provided there are no deficits in visual fields.

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