A guide to pituitary gland tumours

The pituitary is a pea-sized gland that sits at the base of the brain. It is also known as the ‘master gland’ due to it being the manager of the hormones that determine the body’s growth, metabolism, sleep, and sexual reproductive function. The pituitary gland sometimes can develop tumours, and in this article, a master neurosurgeon explains the effect of these pituitary tumours on the body, and how they can be surgically treated.

What is the pituitary gland?

The pituitary gland is a pivotal part of the endocrinal system, the network of glands that produce various hormones that maintain bodily functions – the pituitary gland controls the adrenal glands, the gonads (the ovaries and the testes), and the thyroid. The pituitary gland produces the following hormones:

• Growth hormone (GH)
• Thyroid-stimulating hormone (TSH)
• Adrenocorticotrophic hormone (ACTH)
• Follicle stimulating hormone (FSH)
• Luteinising hormone (LH)
• Prolactin

It also receives and stores hormones (oxytocin and vasopressin, for example) that are produced by the hypothalamus, which is part of the brain that is right on top of the pituitary gland and is the link between the nervous system and the endocrine system.

What is a pituitary tumour?

Pituitary tumours are abnormal growths on the surface of the gland. They are not always cancerous, but they can affect or inhibit the function of the pituitary gland – noncancerous tumours are called adenomas, and they can be further categorised as:

1. Functioning (secreting) adenomas, which can secrete extra hormones that will affect the body externally or internally by altering function.
2. Nonfunctioning (non-secreting) adenomas, which don’t cause an influx of hormones but will put pressure on the brain, eyes or optic nerve. These are the most common.
3. Macroadenomas, which are bigger than 10 millimetres and are most likely to stunt pituitary hormones in what is called hypopituitarism.
4. Microadenomas, which are smaller than 10 millimetres.

What are the effects of a pituitary tumour on the body?

There are several ways a pituitary gland can affect a patient, ranging from visible changes to loss of bodily functions to system disruption.

Pituitary tumours that change in size can affect vision due to the gland’s proximity to the optic nerves at the back of the eyes. Complications can be blurriness, double vision, or a smaller peripheral range. Tumours that get big enough (macroadenomas) can put pressure on the brain and skull, inciting headaches. With enough pressure on the brain, there may be nerve dysfunction which can manifest as drooping facial muscles, loss of coordination, nausea, and even seizures.

When pituitary tumours interfere with normal hormone production, they can cause complications such as:

• abnormal menstrual cycles
• unusual weight gain and loss
• change in libido
• reduced appetite
• chronic fatigue
• mood swings and irritability
• changes in facial features
• growth spurts
• growth in the limbs, hands, or feet

This is because the tumour can hijack the messages being sent to the other glands, causing them to make too many or too few of their hormones.

In the gonads, a pituitary tumour can trigger hypogonadism – where there are too few of the sex hormones (oestrogen, testosterone, and progesterone), causing the body to fail to develop the secondary sexual characteristics (in children) or cause hair loss and breast tissue development (in adults) – or hypergonadism – where there are too many sex hormones, causing excessive body hair growth, increased sex drive, and outbreaks of acne.

In the thyroid which is the producer of thyroxine, it can cause hypothyroidism – which will look like fatigue, dry skin, and swollen limbs – or hyperthyroidism – which will look like heart palpitations, sweating, tremors, and unexpected weight loss.

In the adrenal glands which produce cortisol, it can cause adrenal insufficiency – where there it too little cortisol in the body, resulting in a low blood pressure, nausea, vomiting, low appetite, and abdominal pain – or Cushing’s syndrome – where too much cortisol causes high blood pressure, muscle weakness, bone density degradation, thick stretchmarks, and facial swelling.

How are pituitary tumours diagnosed?

Most cases are actually diagnosed due to the patient undergoing an MRI or CT scan for a different reason. Patients who come to their doctor with concerns regarding the above symptoms will also typically undergo either of these scans to visually confirm the presence of the tumour, or other tests such as a blood test to look at the hormone levels in the body, a urine test to check on the levels of specifically ACTH, or a vision test if the patient if struggling with their sight due to a large tumour.

With the results of these scans and tests, a doctor can confirm or investigate their suspicion of the tumour’s presence.

How can pituitary tumours be treated?

There are a few treatment options available for pituitary glands, and it will depend on how the patient is affected by the tumour, if it is cancerous, and if it is continuing to grow.

There are medications available that shrink tumours and block their influence on the hormones. Patients with cancerous or large tumours that do not respond to this medication will likely benefit more from radiation therapy to kill the cells of the tumour and stop it from growing or metastasising.

For tumours that are stubborn or that are causing damage that needs to be rectified urgently, there are several surgical procedures that remove the tumours, such as:

• Transsphenoidal surgery, also called an adenomectomy, in which an endoscope and other instruments are passed through the nasal cavity to reach the tumour, which can be used to cut the tumour off the surface of the gland. This is one of the most successful techniques for adenoma removal and doesn’t require any incisions, meaning that there will be no scarring and a very quick recovery time. However, macroadenomas that are too large to be pulled out through the nose will not be suitable for this technique.
• Transcranial surgery, also called a craniotomy, in which the tumour is removed instead through the top of the skull, where a section of bone will have been cut away and then replaced at the end of the procedure. This is a less recommended procedure due to its invasive technique.

Regardless of which procedure is used, brain surgery is a major procedure that comes with risks like infection, brain and nerve damage, pituitary gland damage, loss of vision and double vision. Complications are rare, but should appropriately considered before undergoing brain surgery.

If you have concerns about pituitary tumours, contact a specialist via Top Doctors today.