PROLACTINOMA

What is prolactin?

Prolactin is a hormone produced from the pituitary gland. It is naturally produced at higher levels than normal during stressful events, pregnancy and during breast feeding.

It is a small pea size gland situated in a hollow bony pouch, at the base of the brain, at the back of the bridge of the nose. It is the master gland of the endocrine system and controls the functions of the other endocrine glands.

Yes. Prolactin levels can be high in the following circumstances

• When taking certain medicines such as;

Antisickness medicines such as metoclopraminde (Maxolon), domperidone, fentazin and stemetil
Antidepressant medicines
Some antiepileptic medicines
Some antipsychotic medicines such as largactil and sulpiride

If you are taking any of the above please inform your doctor

• When the thyroid is underactive (Hypothyroid). Your doctor will check for this.
• When there is a pituitary adenoma. This is a small growth of the pituitary gland which overproduces prolactin.

In women, excess prolactin can cause infertility, irregular or absent menstrual periods, persistent milk secretion from the breasts, reduced libido and soreness vaginally during sex due to lack of vaginal secretions

In men, excess prolactin can cause impotence, breast development and also secretion of milk from the breasts

In both men and women, the pituitary adenoma can enlarge to the extent that it encroaches on the normal pituitary tissue and surrounding structures. This may lead to a failure of the normal pituitary to produce other hormones and encroachment on the eye nerves can result in visual difficulties.

1. Besides blood test for prolactin your doctor will also check your thyroid hormones

2. Pregnancy test may be required for some women

3. Occasionally a TRH test may be required. In this test a hormone called TRH is injected into a vein and blood taken to check prolactin before and at 20 and 60 minutes later.

4. Vision will be checked including the visual fields using a computerised light screen. Dots of light appear on a screen and the patient has to identify when they are seen. By this method the doctor can assess whether you can see all around you.

5. MRI (or CT) scan of the pituitary gland.

6. Additional blood tests may be required to check for other pituitary hormones if it is thought that they may be underfuctioning. This test is called the Complete Pituitary Function Test.

A raised prolactin is surprisingly common in women and treatment will be tailored to the patients precise situation taking into account your opinion on therapy and requirements (eg need for fertility).

Most patients will be offered medical therapy to lower the prolactin.

These are bromocriptine (Parlodel) taken orally 3x per day, or quinagolide (Norprolac) taken once daily or cabergoline (dostinex) taken orally once or twice per week.

All three medicines can have inconvenient side effects but vary in the extent to which this is noticed by the patient. Some patients can have side effects with one drug but not another so there is a choice. Generally quinagolide and cabergoline produce less side effects than bromocriptine.

What are the side effects?

• Nausea and sickness
• Dizziness
• Dry mouth
• Feeling generally unwell

Often side effects are reduced if the medicine is begun at a low dosage and then the dose slowly increased over days if not in some weeks. Also side effects are less if the drugs are taken with a meal and not on an empty stomach.

What happens when I take these medicines?

In women menstrual periods often return to normal (unless you are menopausal), breast secretion ceases and fertility is a possibility. Also the medicine can cause the pituitary adenoma to shrink and this is often checked after some months by a repeat MRI scan.

Oestrogen can stimulate the adenoma to grow but this is usually countered by bromocriptine, quinagolide or cabergoline, so the low dose oestrogen pill is usually safe with these medicines. Without these medicines the specialist may advise a progesterone only pill.

Most patients have a small pituitary adenoma (often only a few mm in size) but some may have a large adenoma (>1cm) which may have expanded upwards touching the nerves to the eye causing visual difficulties. In this situation the specialist may try to shrink the adenoma initially with medicine such as bromocriptine, quinagolide or cabergoline and then repeat the MRI scan to assess shrinkage. If the adenoma shrinks then medicine treatment alone may be sufficient as long as you are prepared to take the medicine regularly. The reason for this is that the adenoma will re-expand if the medicine is forgotten or taken irregularly.

However if the adenoma does not shrink then surgery to remove it will be required for obviously the medicine is not working. The operation is called pituitary hypophysectomy and is performed up the nose. Operation may also be advised in certain other circumstances especially if the adenoma is large and you are intolerant of the medicine or the tumour needs removed for medical safety reasons. Although the surgeon will try and preserve the normal pituitary tissue this is not always possible and other hormones may be required after surgery. In some circumstances radiotherapy may be required after the operation to further treat and prevent recurrence.

In mild situations where there are no disturbing symptoms, where patients are intolerant of medical therapy, where sex hormones are normal, where there is no risk of brittle bones from lack of sex hormones, then no therapy may be a viable option. However long term followup will be required.

Yes. The usual plan is to continue the medical therapy until pregnancy is confirmed by a test and then to cease the medical therapy. Extensive observation during many pregnancies world wide have shown that your baby will not be harmed by the medical therapy. The specialist will then monitor your progress during the pregnancy possibly repeating the visual field computer tests at regular intervals. Baby will not be harmed by the prolactin rising high again for in a normal pregnancy prolactin rises to very high levels. Nevertheless if you have had the adenoma removed and are producing little or no prolactin do not worry as pregnancy will continue and baby will be unharmed.

Yes as long as you are not taking prolactin lowering medicines as these will be present in your milk. Even after an operation which has resulted in little or no prolactin some women can breast feed.

Yes in some women prolactin can return to normal after a pregnancy, in some there is no change but a few have a worsening of the prolactin level. Once again medical therapy may be required and your specialist will follow you up to check all of this.

For many years. The specialist will advice but often some 5 years minimum is required. Then many patients will still require to continue therapy. At menopause about half will show some improvement of prolactin and may be able to cease therapy but all require follow-up.

Life long therapy will be required for most. Regrettably the pituitary adenoma is often more aggressive than in women and surgery more often required. Here again the specialist will advice.

The Pituitary Foundation
PO Box 1944
Bristol, BS99 2UB.
Tel/Fax 0117 927 3355
e-mail- helpline@pitpat.demon.co.uk

Why not try the website: http://www.niddk.nih.gov/health/endo/pubs/prolact/prolact.htm

or www.pituitary.org.uk

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Ó NHS Tayside; 2006; version 1.0

Disclaimer; no liability whatsoever is accepted for information given and all such information, especially with regard to drug usage (UK version provided), must be checked with a person’s health provider.