Hyperprolactinaemia

Hyperprolactinaemia refers to high levels of prolactin in the blood. Prolactin is a hormone made in the pituitary gland. It plays a role in breast milk production after childbirth and affects male and female reproductive health.

Hyperprolactinaemia can be caused by a range of factors¹. It is important to identify the cause so the correct treatment can be provided. Causes include:

• Prolactinoma
• Other types of pituitary tumours
• Pregnancy
• Breastfeeding or nipple stimulation
• Some medications (including antipsychotic and anti-nausea medicines)
• Underactive thyroid (hypothyroidism)
• Polycystic ovary syndrome
• Kidney or liver failure
• Physical or psychological stress
• Marijuana use

A prolactinoma is a common tumour arising from the pituitary gland that produces the hormone prolactin. They are almost always benign (non-cancerous).

Prolactinomas are grouped according to their size:

• Microprolactinomas are less than 10 mm (1 cm)
• Macroprolactinomas are 10 mm (1 cm) or larger

In Australia, around 450 people each year will be diagnosed with a prolactinoma².

This is far less than the actual number of people who have prolactinomas, as many small prolactinomas never cause symptoms and are not detected. Studies of autopsy results have revealed nearly 1 in 10 people had tiny tumours in their pituitary gland.³

Prolactinomas are most common in women aged between 20 and 34 years. They are very rare in children.

No one really understands what causes a prolactinoma. Most people with a prolactinoma have no family history of pituitary tumours.

If your prolactinoma developed at a young age and/or you have a family history of pituitary or other endocrine (e.g. parathyroid, pancreas and adrenal) tumours, your doctor may discuss the option of genetic testing with you to look for rare genetic changes (mutations) that may be passed on in family members.

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In some people, hyperprolactinaemia causes no symptoms or signs¹.

In others, the symptoms of hyperprolactinaemia are caused by its effect on bone health, breast health and reproductive function¹. These include:

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Your doctor may ask you questions about:

• Your periods (for women) or whether you can get erections (for men)
• Changes in sex drive
• Any discharge from your breasts (men and women)
• Headaches and visual symptoms
• Medications, supplements and herbal therapies you may be taking
• If you are pregnant (which may be confirmed with a pregnancy test).

A blood test will be done only if you have symptoms or signs of hyperprolactinaemia, or a known pituitary problem1. This test is used to measures the levels of prolactin, and other hormones in your blood. A small amount of blood is taken and sent to a laboratory for testing. An elevated prolactin will often be confirmed on a second blood collection.

Different laboratories use different methods for testing, and so normal reference ranges can vary. This can make comparison of results between laboratories and other people difficult.

Your doctor may send you for an MRI (magnetic resonance imaging) to check the size and shape of your pituitary gland. An MRI scan uses a magnetic field and radio waves to take pictures of parts of the body. Before having an MRI, you will usually change into a gown and remove any watches or other metallic objects. You might be given earplugs or headphones, as the MRI machine can be noisy. Some people with metal in their body (for example, some pacemakers, welding injuries with metallic foreign bodies in their eyes) cannot have an MRI.

For the scan, you will lie on a platform that slides into the MRI machine. You will need to lie very still while inside the machine, as movement can blur the images. When inside the MRI machine, you will still be able to talk to the operator through an intercom system. The scan can take up to an hour. If you have significant claustrophobia, your doctor may be able to arrange for you to have light sedation during the scan.

Your doctor may organise to test your vision. This is because prolactinomas can push on the nerves that connect the eye to the brain, called the optic nerve. This causes patchy or blurred vision, particularly at the far edges of your sight. Vision tests are most often conducted through eye specialists (an optometrist or ophthalmologist).

Your doctor may test your bone mineral density. This is because prolactinomas can increase the risk of osteoporosis (thinning and weakening of the bones, resulting in an increased risk of fracture). The best way to test bone mineral density is using a DEXA scan (Dual Energy X-ray Absorptiometry scan). This is a fairly quick (10-30 minutes) and painless imaging procedure with very little radiation exposure. It involves lying fully clothed on a platform while a scanner passes over you to take pictures of your hip, spine and, sometimes, forearm.

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Your doctor will tailor the treatment of your hyperprolactinaemia based on your symptoms and test results. Some people do not require any treatment, while others may require medication and/or surgery. Prolactinomas often stay the same size for many years and if they grow, they do so very slowly. The treatment plan will depend on the cause of your hyperprolactinaemia.

If the hyperprolactinemia is due to medications you are taking, your doctor will discuss whether you can stop taking the medication, or whether an alternative exists that will not increase your prolactin levels. Sometimes your medications cannot be changed, in which case your doctor will discuss other options with you.

If the hyperprolactinemia is due to hypothyroidism, your doctor will treat the hypothyroidism first, and monitor your prolactin levels to make sure they return to normal.

The first step in treatment is generally medication, but if there are no symptoms and only a very mild elevation in prolactin level, no treatment may be necessary. Surgery and radiation therapy are occasionally used to control prolactinomas that continue to grow despite medication or where the medications cause troublesome side effects.

The medication used to treat prolactinoma is called a dopamine agonist. Commonly used dopamine agonist medications include cabergoline (trade name, Dostinex), bromocriptine (trade name, Parlodel) and quinagolide (trade name, Norprolac). Dopamine agonists act like dopamine, causing the pituitary gland to make less prolactin. In many people, prolactin levels return to normal within a few weeks to a few months of starting treatment. It usually takes longer to see a reduction in the size of the prolactinoma.

You will need to continue taking the medication as prescribed. Otherwise, the prolactinoma can grow and/or symptoms can return. In many cases, you will need to keep taking the medication for a long period of time. In some cases, the medication can eventually be reduced or even stopped. Your doctor will regularly measure your hormone levels to make sure the dose is correct, and the medication is working.

Your doctor will generally start you on a low dose and may increase the dose over time. This can help avoid any side effects, including nausea, nasal stuffiness, dizziness/faintness, constipation, sleepiness, headache, worsening of anxiety and/or depression. Rare side effects can include addictive behaviours (e.g. involving sexual activity, gambling, shopping or eating), auditory hallucinations (hearing things), mood changes and delusions. You should notify your doctor as soon as possible if these rarer side effects occur as they may recommend that you reduce or stop your medication. These side effects usually resolve very quickly once medication is stopped. Other treatments may be considered if the prolactinoma is still present.

In other medical conditions where cabergoline is used in higher doses it can cause scarring of the heart valves leading to heart failure. However, current evidence suggests that cabergoline does not cause heart valve scarring in the low doses usually used to treat hyperprolactinaemia.

In women, successful treatment usually results in restoration of fertility (particularly in microprolactinomas). To prevent unwanted pregnancy, birth control may be needed. In women with microprolactinomas who do not wish to fall pregnant in the near future, the oral contraceptive pill may be used instead of dopamine agonist medications in order to restore normal sex hormone (oestrogen and progesterone) levels and improve bone density.

If you are pregnant or planning to get pregnant, your doctor may change your medication. In microprolactinomas, the medication can often be stopped once you are pregnant. If surgery is required – for instance, in large prolactinomas – your doctor may try to arrange for this to occur well before any planned pregnancies. It is helpful to discuss any plans for children with your doctor ahead of when you start trying to conceive.

Most prolactinomas respond to medication, and do not require surgery. Surgery may be needed if the prolactinoma is large and pressing on nerves or brain tissue or is growing despite medication or if the medication is not tolerated. There are two types of surgery to remove prolactinomas. Your surgeon will choose the best method based on the size and extent of the prolactinoma.

Transnasal transsphenoidal surgery is the most common procedure. This surgery is often done by two surgeons: a neurosurgeon; and an ear, nose and throat (ENT) surgeon. The ENT surgeon uses an endoscope (a very thin fibre optic tube with a camera on the end) to navigate through one of your nostrils to the back of the nose where a small cut is made to access the pituitary gland. The ENT surgeon uses the endoscope to assist the neurosurgeon to see and remove the tumour. Larger tumours may need to be removed in smaller pieces. Once the tumour is removed a piece of tissue from the inside of your nose or some fat tissue is used to patch the hole at the back of the nose. This surgery leaves no visible scars.

The surgery takes about 2-3 hours and you will stay in hospital for 3-5 days. During your hospital stay your urine output is watched carefully and you may be prescribed some steroid medication for a few days. You will have regular blood tests while in hospital. After surgery, it is fairly common to have a mild headache and nasal congestion for up to 2 weeks. You will have another blood test 4-6 weeks after surgery to check your prolactin and other hormones levels. Thereafter, your prolactin and hormone levels will be checked periodically. An MRI scan will be done after 3-6 months. If symptoms reappear, blood tests and scanning will be repeated.

Transcranial surgery is when the pituitary is operated on through a cut in the forehead. It is only rarely performed in very large prolactinomas, which can make it difficult to remove all the tumour through the back of the nose.

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You should see your doctor (GP) if you have the following symptoms. Your GP can refer you to an endocrinologist – a doctor specialising in hormones and glands.

Seeing your doctor or having a medical problem can be stressful. It often takes time for information to sink in and it is very common to feel overwhelmed by what is happening.

Sometimes it is helpful to write down questions for your doctor before you go.

Some questions that might be useful for you are:

• Do I need medication for my hyperprolactinaemia?
• Do I need to take other hormone supplements or medications?
• What are my choices for medication?
• How quickly should the medicine work?
• For how long do I need to take my medications?
• What should I expect with my symptoms?
• Does my medication have any side effects?
• Do I need to have an MRI?
• Do I need a bone mineral density scan?
• Do I need surgery?
• Can I get pregnant if my medication works?
• Do I keep taking my medication if I get pregnant?
• Will I be able to breastfeed while taking medication?
• Do I need another appointment?

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Adenoma – A non-cancerous tumour that occurs in glands.

Amenorrhoea – Absent menstrual periods.

Benign – A benign tumour is one that is not cancerous.

Galactorrhoea – Milky discharge from the breast in men and in women (not due to breastfeeding).

Gynaecomastia – Enlarged or swollen breasts.

Libido – Interest in sex; sex drive.

Microprolactinoma – A tumour that is less than 10 mm (1 cm) in size.

Macroprolactinoma – A tumour that is 10 mm (1 cm) or larger.

Malignant – Contains cancerous cells.

Oligomenorrhoea – Irregular menstrual periods.

Pituitary Gland – A gland located at the base of the brain. It is often called the master gland, because it controls several other glands in the body.

Prolactinoma – A tumour of the pituitary gland.

Tumour – An abnormal swelling or growth in the body. Can be benign or malignant.

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The content on this page was medically reviewed Dr Ann McCormack, Dr Morton Burt, Dr Carmela Caputo and Dr Sunita De Sousa.

We are extremely grateful to Dr Yi Yuen Wang and the volunteers at the Australian Pituitary Foundation for reviewing this information.

Page last reviewed on 3 Feb 2019