Non-functioning adenoma (NFA) is the second most common type of pituitary tumour—accounting for between 30 and 50% of cases. Fortunately, NFAs are usually a slow growing mass of pituitary cells that are benign, or a non-cancerous growth. As the name suggests, these tumours do not produce an excess of hormones. For this reason, you usually only become aware of NFAs when they become large and begin to compress surrounding structures which may include normal pituitary tissue and vision pathways.
In Australia, about 230 people are diagnosed annually with a NFA, while about 5000 are living with the condition.
In a small percentage of cases there is an inherited predisposition to NFAs. However, for the majority of people, the exact cause of a NFA is unknown. It is likely that genetic changes lead to the tumour developing, but researchers are still searching for the triggers causing these changes.
The first symptoms of a NFA generally occur when the tumour grows larger then 1 cm in diameter (at this size, the tumour is called a macroadenoma). In about 70% of people with a NFA this size, one of the first symptoms is a blurring of vision or loss of peripheral vision as the tumour presses on the optic nerve. This is often accompanied by headaches behind the eyes, nausea and vomiting.
A large NFA will also compress the pituitary gland. With the gradual compression of the gland, it produces lower and lower levels of pituitary hormones, leading to a condition known as hypopituitarism. Symptoms may include loss of sexual function, irregular menstrual periods and infertility. It may also cause reduced thyroid and cortisol levels. Less often, the NFA can press on the pituitary stalk leading to hyperprolactinaemia or higher levels of the hormone, prolactin.
In 5-13% of patients with a pituitary tumour, acute symptoms arise following a sudden bleed or circulation blockage within the tumour. The tumour expands rapidly causing headaches and vision problems as well a lack of pituitary hormones (especially cortisol, leading to adrenal insufficiency). When this occurs, it is called ‘apoplexy’.
Testing and Diagnosis
Most NFAs are diagnosed when they become large. An endocrinologist will order blood tests to assess your pituitary hormone levels and will also refer you for an MRI scan to determine the type, size and location of the tumour. The endocrinologist will refer you to a neurosurgeon who specialises in pituitary surgery.
An ophthalmologist will perform visual testing to establish your baseline visual status.
If your tumour isn’t causing any symptoms, treatment is often put on hold—particularly if you are older. In this situation, your tumour’s growth is monitored using MRI scans. The regularity of the scans may vary from every 6 to 12 months up to once every five years. At some point, you may require treatment for hypopituitarism and vision problems.
If treatment is required surgery may be recommended depending on the size and growth of the tumour into the surrounding brain or cavernous sinus.
When surgery isn’t possible, or the whole tumour cannot be removed, than radiotherapy is the second line therapy. Long-term, radiotherapy can damage the pituitary gland, so you will require ongoing monitoring to check for pituitary failure.
The cure rate for NFA is high, especially if the surgeon is able to remove the entire tumour.
Post-treatment, all patients require regular monitoring to check the pituitary gland is functioning normally. If the gland is compromised, you may need long-term hormone replacement medication. (Tell your endocrinologist if feel like you’re fatiguing more quickly or your memory isn’t as good. These are common symptoms of pituitary failure.)
Following treatment, most patients experience an immediate improvement, or at least stabilisation, in their vision. However, initially you will still need to have your vision monitored by an Opthalmologist and may require MRI scans in the first year post treatment. The frequency of the scans will gradually decrease depending on your circumstances. Other symptoms, such as headaches, also improve post treatment.
Want to know more?
You can download the Pituitary Foundation’s booklets:
Is it Non-Function Adenoma? A patient’s guide to diagnostic testing
Is it hypopituitarism? A patient’s guide to diagnostic testing