How is a Prolactinoma treated?
Whatever the size of your prolactinoma, it is likely that your treatment will be with tablets.
Drugs known as dopamine agonists are the first line medication in patients presenting with a prolactinoma. There are three available medications. All these drugs act by reducing prolactin secretion by the prolactinoma.
- Cabergoline (brand name – Dostinex), is long acting and requires one or two doses per week. The usual dose of cabergoline is one tablet (0.5mg) once or twice a week, although higher doses are occasionally required. Sometimes the dose can be reduced later during long-term treatment.
- Bromocriptine (brand name – Parlodel) is usually given twice or three times daily (one tablet 2.5mg)
- Quinagolide (brand name – Norprolac) is taken once daily, with the dose increased gradually to 75micrograms.
These drugs are safe and well tolerated by most people. To minimise any side effects, particularly dizziness on standing up, nausea and headaches they should be taken with food. Cabergoline should to be taken at night when going to bed with a light supper or snack e.g., tea/milk and a biscuit. This should reduce the chance of any unwanted effects.
Your doctor will give you instructions on how to build up the dose slowly, again to minimise any side effects, particularly dizziness on standing up and headaches. Generally, these side effects will diminish as your body becomes used to the medication but should they persist or become unbearable please discuss with your consultant or endocrine nurse specialist at your endocrine clinic.
Occasionally, the medications may cause slight constipation, but this can usually be cured by increasing the amount of fibre in your diet. Other side effects include tiredness, abdominal pain, breast discomfort and nasal congestion. Psychological disturbance may be a rare complication of either cabergoline or bromocriptine.
Impulse control disorders such as pathological gambling and hypersexuality can occur in patients taking dopamine agonists. Due to the unusual nature of these behaviours, often an association is not made with the medicine. High doses and dose increases of dopamine agonists can trigger the development of impulsive behaviours. Patients and their family/caregiver should be alerted to the possibility of these reactions and encouraged to seek help from their doctor if they notice unusual behaviours.
Prolactin levels often fall to normal within a few weeks of starting the treatment. In women, once prolactin has fallen to normal, menstrual cycles usually resume; interest in sex is regained and fertility is restored in most cases. In men, testosterone levels may raise, which often improves sex drive and potency.
Nearly all prolactinomas shrink in size following treatment with the tablets. If your prolactinoma is pressing on the nerves to the eyes, there is a good chance that your vision will improve as the tumour shrinks. If you have a large prolactinoma, you may have several pituitary scans over the months and years so that the shrinkage can be assessed.
Fertility may return quite quickly, so if you do not wish to become pregnant, you and your doctor will need to discuss an effective method of contraception, before medication is started.
If pregnancy is wished, it is advisable to see your endocrinologist for pre-pregnancy planning and advice.
Once pregnancy is established, it is normally recommended for people to discontinue medication but you should seek advice from your endocrinologist. You will continue to be seen by your endocrinologist throughout your pregnancy, to monitor progress.
Checking blood levels of prolactin during pregnancy is unhelpful since they rise during a normal pregnancy. There is good safety data for babies conceived whilst the mother is taking dopamine agonists.
If you wish to breast feed you should discuss this with your endocrinologist during your pregnancy. Following the birth, you will be reassessed by your endocrinologist regarding the need for further treatment for your Prolactinoma.
The use of surgery and radiotherapy for prolactinomas has declined in recent years, due to the remarkable effectiveness of tablet treatment. If your prolactinoma does not shrink with tablet treatment (less than 10%) or you suffer side-effects, then surgery may be required, particularly if your vision has not improved.
The operation is called a trans-sphenoidal surgery which occurs through the air sinuses at the back of the nose and uses an operating microscope. In some areas you may be offered endoscopic trans-sphenoidal surgery – the same surgery but using a camera.
If a large prolactinoma does shrink effectively following tablet treatment, most specialists simply continue the drug, but perhaps in a reduced dose. General pituitary function may improve after tumour shrinkage has occurred.
However, if you continue to have pituitary under-activity following treatment of your prolactinoma, then hormone supplements may be required. These may include steroid tablets for adrenal under-activity, thyroid hormone tablets for thyroid under-activity and possibly, oestrogen HRT for women or testosterone supplements for men. Growth hormone replacement therapy may also be required.
If you notice any clear watery fluid coming from one or both nostrils, report this immediately to your doctor, just in case it might be leakage of CSF (cerebrospinal fluid which surrounds the brain).