What is a Prolactinoma?
A prolactinoma is a prolactin-producing tumour of the pituitary gland. This is a benign tumour, and not a brain tumour or cancer.
Doctors use the words ‘tumour’, ‘adenoma’ or ‘growth’ which means a swelling on the pituitary gland. These tumours only grow very slowly and many do not seem to grow at all.
We do not know exactly what causes prolactinomas, but they are the most common type of hormone-producing pituitary tumour.
Prolactinomas come in various sizes, but the vast majority are less than 10mm (3/8 inch) in diameter. These are called microprolactinomas. The rarer, large tumours greater than 10 mm in size are called macroprolactinomas. Prolactinomas can occur in men and women. The symptoms produced by a prolactinoma depend on the sex of the patient and the size of the tumour.
The pituitary gland produces a number of hormones, including prolactin, ACTH, TSH and GH, follicle stimulating hormone (FSH) and luteinizing hormone (LH).
Prolactin is sometimes known as the ‘milk hormone’ because it stimulates milk production after childbirth, but it is also produced in men, although in smaller amounts.
FSH and LH control sex and reproduction. In women they cause release of the sex hormone oestrogen and stimulate the ovaries to produce eggs; these hormones are essential for a normal menstrual cycle. In men, they cause the release of testosterone and stimulate production of sperm from the testicles.
What causes the Prolactin level to be raised?
Common causes of raised prolactin include:
- Nipple stimulation and suckling
- Certain medications such as:
- Anti sickness medications e.g. Metoclopramide, stemetil, Domperidone, also acid reducing medication like Omeprazole can raise your prolactin level.
- Certain antidepressants and tranquillisers used to treat mental health illness can raise prolactin: examples include Amytriptyline and Fluoxetine (Prozac) and risperidone.
- Some homeopathic and herbal medications.
- An under active thyroid gland, which can be diagnosed by a simple blood test and which requires treatment with thyroid hormone tablets.
- A benign condition called macroprolactinaemia, which is an artefactual elevation of serum prolactin measurement, as a result of prolactin with certain blood proteins. It is of no clinical significance but must be distinguished from prolactin-producing pituitary tumours.
Once your doctor has excluded these causes, they will consider the possibility of a prolactinoma.