A prolactinoma is a benign tumour (a non-cancerous
swelling) in the pituitary gland. Prolactinomas make large amounts of a
hormone called prolactin.
The pituitary gland gland lies just
below the brain. It makes several hormones, including a hormone called
prolactin. (A hormone is a chemical which is made in one part of the
body, but passes into the bloodstream and has effects on other parts of
the body.)
Prolactin helps the body produce milk when a woman breastfeeds. It also has effects on other hormones in the body.
What causes prolactinomas?
A prolactinoma
occurs when some of the cells in the pituitary gland (the ones
producing prolactin) multiply more than usual. We do not know what
makes the cells multiply in the first place. In rare cases, there may
be a genetic (inherited) cause.
What are the different types of prolactinoma?
Small
prolactinomas (less than 10mm) are called ‘microprolactinomas’. Larger
ones (more than 10mm) are called ‘macroprolactinomas’. There is also a
rare type called ‘giant prolactinomas’ which are more than 4cm.
Who gets prolactinomas?
About 1 in 10,000
people have a prolactinoma. Prolactinomas are most common in women aged
20 - 50 years, but they can occur at any age and in men too.
Prolactinomas are the most common type of pituitary gland tumour.
What are the symptoms of prolactinoma?
High levels of prolactin in the blood can cause various symptoms. The symptoms differ slightly between men, women and children.
Women may have:
- Irregular periods or no periods.
- Reduced fertility.
- Reduced sex drive.
- Milk leaking from the breasts (known as ‘galactorrhoea’). The milk
may leak out by itself, or may only show when the breast is squeezed.
(Note: leakage of milk from the breasts is normal towards the end of
pregnancy, with recent childbirth, if breastfeeding, and for some time
after finishing breastfeeding.)
- Increased growth of hair on the face or body
Men may have:
- Reduced fertility.
- Erectile dysfunction (difficulty having an erection).
- Reduced libido (reduced sex drive).
- Breast enlargement (called 'gynaecomastia').
- Very rarely, leakage of milk from the breasts.
Children and teenagers may have:
- Reduced growth.
- Delayed puberty.
Prolactinomas which are large may press on the brain or nearby
nerves (the nearest nerves are the optic nerves which go to the eye).
This may cause symptoms such as:
- Headache.
- Eye symptoms – you may get reduced vision or double vision. The
early changes can easily go unnoticed, because they affect the
‘peripheral’ vision – that is, the edges of your vision to the extreme
left and right. This means that you may see less of what is around you,
but can still see well if you focus on something directly.
If you have headaches or reduced vision, see a doctor urgently
- you may need to have treatment promptly to relieve the pressure on
the optic nerves.
Rarely, the prolactinoma may press on the
rest of the pituitary gland, stopping it from producing other hormones.
This can cause symptoms such as tiredness, fainting, low blood
pressure, low blood sugar or collapse. Also, rarely, there may be a
leakage of the fluid that surrounds the brain and pituitary gland, felt
as watery fluid leaking through the nose. These symptoms need urgent
treatment.
How is prolactinoma diagnosed?
The diagnosis
may be suspected from the symptoms. Women tend to be diagnosed earlier
than men, because a change in the woman’s periods is an early symptom
and is easily noticed. Some prolactinomas are diagnosed by chance, if
you have tests for another reason. If a prolactinoma is suspected, you
may be offered several tests.
Blood tests
A blood sample to check the
level of prolactin in the blood. If a high prolactin level is found,
you may be asked to have a repeat test. This is because prolactin
levels can be affected by many other things in the body, such as sleep
or stress. It may help to take the blood sample when you are reasonably
rested and have been awake for at least two hours.
The normal
level of prolactin is less than 400mU/l. A very high prolactin level
(>5000 mU/l) usually means that a prolactinoma is present. Levels in
between may be due to a prolactinoma, or to other causes (see below,
'what else could it be?').
Other blood tests may be done at the
same time. It is important to test the thyroid gland and to check
kidney function, as both these can affect prolactin levels. Further
tests may be needed to see if the tumour is causing a lack of other
hormones made by the pituitary.
Eye tests
Eye tests will assess if the tumour is pressing on the optic nerve – this includes a test of ‘visual fields’.
Scans
An MRI scan (magnetic resonance
imaging scan) or CT scan (computed tomography scan) can show the size
of the tumour. A bone density scan may be advised for some patients, to
check whether you are at risk of osteoporosis (which is a possible
complication - see below)
What else could it be?
Apart from
prolactinomas, there are other causes of raised prolactin levels. For
example, some medicines may cause high prolactin levels. These include:
the anti-sickness medicines metoclopramide and domperidone;
antidepressants of the 'SSRI' type, and some medications used to treat
schizophrenia or bipolar disorder. There are other less common causes
for a raised prolactin level.
What are the treatments for prolactinoma?
Treatment
usually works well to stop the symptoms of prolactinoma and to improve
fertility. There are various treatments – the usual one is medication.
Note:
If you are a woman starting treatment for a prolactinoma, remember that
the treatment could improve your fertility quite quickly, and you could
possibly become pregnant before you even have a period. So if you do
not want a pregnancy, you will need to use contraception. Discuss this
with your doctor, nurse or family planning clinic if you need advice.
Not treating may be an option
For a small
prolactinoma (a microprolactinoma), if symptoms are not too
troublesome, then one option is just to monitor the situation. This
means having repeat blood tests and possibly scans at regular
intervals. If symptoms get worse or the prolactinoma seems to be
growing, treatment can be started whenever necessary.
If you are
choosing the no-treatment option, your doctor may advise taking
maintenance hormone treatment - to provide oestrogen hormones (for
women) or testosterone hormones (for men). This is because
prolactinomas can cause low oestrogen or low testosterone levels in the
body. In the short term, low oestrogen and low testosterone levels are
not harmful, but in the long term this could lead to osteoporosis.
Also, you may feel better if you have enough oestrogen or testosterone
in your body.
For women, oestrogen may be taken in the form of
the 'combined contraceptive pill' or as 'hormone replacement therapy',
depending on your age and whether you need contraception. For men,
testosterone can be taken by mouth, in patch or gel form or by
injection once a month.
Medication
Medication is a very effective
treatment for most prolactinomas. The medication is a type called
‘dopamine agonists’. These act on the pituitary gland to reduce the
amount of prolactin it makes, and they can also shrink the tumour.
Usually with this medication, prolactin levels go down to normal in a
few weeks. Dopamine agonists can be taken as long-term treatment.
The
dopamine agonists are called bromocriptine, cabergoline or quinagolide.
They are taken as tablets. There are pros and cons of each one - ask
your doctor for details.
Are there any side-effects of dopamine agonists?
Possible side effects are nausea, dizziness, constipation, headaches
and drowsiness. These are less likely if you start with a low dose and
increase gradually. If you feel drowsy, do not drive or use dangerous
machinery.
There
have been recent concerns that dopamine agonists may cause fibrosis
(hardening and damage) of internal organs - if taken in high doses
long-term. It is still uncertain how much of a risk there is from these
medicines. The research about this dealt with dopamine agonists used in
a different situation, to treat Parkinson’s disease, where the doses
taken are much higher than for prolactinomas. More details are in the
'Society for Endocrinology' reference below.
What about treatment in pregnancy?
If you are planning a pregnancy, it is best to discuss treatment
options with your doctor beforehand. Treating the prolactinoma usually
improves fertility, so can help you become pregnant. Bromocriptine is
thought to be the safest of the dopamine agonists for pregnancy,
because it is the most ‘tried and tested’ one. Many women have had
babies after taking bromocriptine.
Discuss
with your doctor what to do if you become pregnant. Some women are
advised to stop medication during all or part of the pregnancy.
Bromocriptine can be used in pregnancy if required.
During
pregnancy, some prolactinomas can get bigger. If you have any symptoms
such as headache or reduced vision, see a doctor immediately so that
this can be checked.
Surgery
Surgery may be an option if
medication does not work, is not wanted, or for larger prolactinomas.
The operation is called 'trans-sphenoidal surgery', because the surgeon
gets to the pituitary through the sphenoid bone, via a small cut above
the upper front teeth or from inside a nostril. It is done under
general anaesthetic.
Radiotherapy
Radiotherapy (X-ray treatment)
focuses high intensity radiation at the prolactinoma, to destroy the
abnormal cells. It is not usually needed for prolactinomas - however,
it may be used rarely, if other treatments are not sufficient. It can
have side-effects.
Other treatments
Sometimes prolactinomas
cause a reduction in the other hormones that the pituitary gland
produces. If so, you may need to take tablets to replace these
hormones. This will depend on your symptoms and blood test results.
What are the complications of prolactinoma, and how are they prevented?
The
main complication is the risk of osteoporosis (thinning of the bones),
if high prolactin levels are untreated for a long time (over one year).
This is because the high prolactin reduces oestrogen or testosterone
levels, which can lead to osteoporosis. Osteoporosis can be prevented
by treating the prolactinoma (as above), which reduces prolactin
levels. Alternatively, replacement oestrogen or testosterone can be
taken.
Large prolactinomas may cause complications if they grow
and press on the structures nearby: the pituitary gland, the brain and
the nerves to the eye. To prevent this, large prolactinomas should
usually be treated (see treatment section). If untreated, the pressure
might eventually lead to loss of vision, other hormone problems (which
could cause severe illness) or severe headaches.
Rare complications are:
- A leak of fluid from around the brain into the nose, which means that there is a risk of infection such as meningitis.
- 'Pituitary apoplexy' is a rare but serious complication, when there
is a bleed inside the tumour, making it suddenly expand. This causes
sudden increasing symptoms such as headache and reduced vision, and may
cause collapse. It needs urgent treatment and may require surgery.
- It is possible, but extremely rare, for a prolactinoma to be malignant (cancerous).
What is the outlook for prolactinoma?
The
outlook is very good. Most prolactinomas are successfully treated with
medication. If this does not work, surgery is usually successful.
Treatment for women can restore periods and fertility (assuming that
the fertility problem was due to the prolactinoma). For men also,
fertility can improve with treatment, but you may need to take
additional medication called 'gonadotrophins' in order to father
children.
For some patients, the prolactinoma itself may be
cured after about three years of taking medication. So you may be able
to come off treatment.
Prolactinomas can recur (come back), even
after successful treatment with medication or surgery. You will still
need monitoring (such as regular blood tests) to check that the
prolactinoma has not come back. If it has, then treatment can be
restarted.
Further help and information
Pituitary Foundation
PO Box 1944, Bristol, BS99 2UB
Tel: 0845 450 0375 Web: www.pituitary.org.uk
Support and information for patients with pituitary conditions, including prolactinoma.
References
-
The Pituitary Foundation
-
Segu VB; Prolactinoma. eMedicine, May 2006.
-
Position statement on the use of dopamine agonists in endocrine disorders, Society for Endocrinology (September 2007)
-
Gillam MP, Molitch ME, Lombardi G, et al; Advances in the treatment of Prolactinomas. Endocr Rev. 2006 May 26. [abstract]
-
Pena KS, Rosenfeld JA; Evaluation and treatment of galactorrhea. Am Fam Physician. 2001 May 1;63(9):1763-70. [abstract]
-
Roth BL; Drugs and valvular heart disease. N Engl J Med. 2007 Jan 4;356(1):6-9.
-
Schade R, Andersohn F, Suissa S, et al; Dopamine agonists and the risk of cardiac-valve regurgitation. N Engl J Med. 2007 Jan 4;356(1):29-38. [abstract]
-
Zanettini R, Antonini A, Gatto G, et al;
Valvular heart disease and the use of dopamine agonists for Parkinson's
disease. N Engl J Med. 2007 Jan 4;356(1):39-46. [abstract]
© EMIS and PiP 2008 Updated: 22 May 2008
