Prolactinoma
What is a Prolactinoma?
A prolactinoma is a tumour of the pituitary gland that produces the hormone prolactin. It is a benign (non-cancerous) tumour and is not a brain tumour or a form of cancer.
Doctors may use the terms “tumour”, “adenoma” or “growth” to describe a swelling on the pituitary gland. These tumours usually grow very slowly.
Prolactinomas vary in size, but most are less than 10 mm (3/8 inch) in diameter. These are called microprolactinomas. Larger tumours, more than 10 mm in size, are called macroprolactinomas and are less common. Prolactinomas occur in both men and women. The symptoms depend on the person’s sex and the size of the tumour.
About Prolactin
The pituitary gland produces several hormones, including prolactin, ACTH, TSH, growth hormone (GH), follicle-stimulating hormone (FSH) and luteinizing hormone (LH).
Prolactin is sometimes called the “milk hormone” because it stimulates milk production after childbirth. It is also produced in men, but in smaller amounts.
FSH and LH control sexual function and reproduction. In women, they stimulate the ovaries to produce eggs and the sex hormone oestrogen; these hormones are essential for a normal menstrual cycle. In men, they stimulate the testicles to produce sperm and the sex hormone testosterone.
What causes the Prolactin level to be raised?
Common causes of raised prolactin include:
- Pregnancy
- Nipple stimulation and suckling
- Stress
- Certain medications such as:
- Anti-sickness medications, for example Metoclopramide, Stemetil and Domperidone, and some acid-reducing medicines such as Omeprazole can raise prolactin levels.
- Certain antidepressants and tranquillisers used to treat mental health conditions can raise prolactin; examples include Amitriptyline, Fluoxetine (Prozac) and Risperidone.
- Some homeopathic and herbal remedies.
- An underactive thyroid gland, which can be diagnosed with a simple blood test and treated with thyroid hormone tablets.
- A benign condition called macroprolactinaemia, where prolactin binds to certain blood proteins and causes an artificially high prolactin reading. It has no clinical significance but must be distinguished from prolactin-producing pituitary tumours.