What is a Pituitary Tumour (a.k.a. Pituitary Adenoma)?


Tumours of the pituitary gland (known as pituitary adenomas) are actually pretty common; they make up about 13% of all diagnosed brain tumours, and often they don’t cause any symptoms at all. My pituitary tumour is called a TSHoma, and it’s super rare. Read on to find out more about all kinds of pituitary adenomas…

Hang on a second… What exactly is the pituitary gland?

The pituitary is a little gland about the size of a pea, which sticks out of the base of the brain. It basically sits way back in your head, directly behind the very top of your nose, between your eyebrows (unless, of course, you’re Frida Kahlo). Even though it looks pretty insignificant, the pituitary gland produces a variety of different hormones. These hormones regulate stress, metabolism, growth, reproductive processes and more. It’s an important part of the endocrine system and in fact is sometimes known as the ‘master gland’, so problems with the tiny pituitary can affect the entire body. Adult pituitary disease is usually caused by a tumour, called a pituitary adenoma.

What happens when pituitary tumours do cause symptoms?

Even though most pituitary tumours are benign (i.e. not cancerous), they are sited close to important brain structures, blood vessels and the optic nerve. As a result, they can cause headaches, loss of sight, and play havoc with the endocrine system… which basically means they can play havoc with your whole body! That’s because around 75% of these tumours are “secretory”, meaning that they actively produce one or more pituitary hormones. The other 25% of tumours often result in the under-production of hormones by the pituitary gland, basically by squashing it. My TSHoma produces Thyroid Stimulating Hormone (TSH – hence the name), meaning I get the symptoms of hyperthyroidism.

How do you diagnose a pituitary adenoma?

Diagnosing a pituitary tumour is not easy. Many of the symptoms of a pituitary tumour are quite easy to dismiss, or to misdiagnose as something else, which means that they are often not diagnosed until they are quite large or producing significant amounts of hormones which are causing more unusual symptoms. Many pituitary patients report having to return to their doctors a number of times before finally getting a diagnosis. If you feel your doctor is not listening to you, I’ve written about some techniques you can use to try to get your doctor to listen and engage more.

Diagnosis of pituitary tumours is usually through epic amounts of blood tests. Urine tests are used in the case of Cushing’s Disease, where the tumour produces a hormone called ACTH. Then, MRI scanning (or CT scanning if MRI is not recommended), which will usually give a picture of the adenoma itself. These tumours are classed as either “microadenomas”, when they are less than 10mm in size, or “macroadenomas”, when they are larger than 10mm.

But why not do the MRI scan first rather than stealing pints of blood from the patient? It’s actually because pituitary adenomas are actually so common in the general population. Endocrinologists want to be confident that the adenoma on the scan is really what’s causing the patient’s symptoms. It would be terrible to tell a patient that they have a diagnosis, put them through surgery, and then discover that in fact the tumour on their pituitary gland was not the cause of their illness, but was simply an incidental finding and as such could have been left alone.

I’ve written about what to expect during a pituitary MRI scan, and how to manage claustrophobia or anxiety during MRI scans, on the blog.

How do you treat a pituitary adenoma?

Given the many different hormones that can be produced  by pituitary adenomas, the symptoms and treatments can vary between different types of tumour. Equally, if the pituitary tumour suppresses rather than increases the production of hormones, this can be extremely dangerous. For instance, a life-threatening Addisonian crisis can be caused if the body does not produce enough ACTH.

Although the precise details will vary depending on the type of tumour and the size of the tumour, usually, the treatment options for pituitary adenomas boil down to three choices: surgery to remove it, medication to treat it, or radiation treatment to try to kill it off. The choice of which treatment to have will be agreed with your doctors, but of course it’s a big decision to make. I’ve blogged about a useful process you can follow to help in making treatment decisions here, which may help if you’re finding it too difficult or overwhelming.

What kind of pituitary tumour do I have?

The main reason I’m a sickly Mama is that I have a pituitary tumour which produces too much thyroid-stimulating hormone (TSH). This kind of tumour is known as a TSHoma or thyrotropinoma, and they’re super rare. I was diagnosed with the tumour in 2010, but I had symptoms for a long time before then. The symptoms of my tumour were mostly the same as those of hyperthyroidism (racing heart, palpitations, shaking hands, hair loss, anxiety and increased appetite) because it caused my body to over-produce thyroid hormones.

How rare are TSHomas?

When I was diagnosed in 2010 I was told this type of tumour had a prevalence of one in a million. A more recent 2015 study in Ireland gave a prevalence of 3.3 per million. In fact, these tumours are probably quite under-diagnosed and more common than previously thought.

How has my TSHoma been treated?

I’ve had surgery on my TSHoma pituitary tumour (called transsphenoidal hypophysectomy) twice, in 2011 and 2013. Although we haven’t managed to get rid of the tumour completely, it’s currently managed with medication. I’ve written a blog post about my experience of pituitary tumour surgery here.

Because TSHomas are so rare, there are actually no medications which are licensed to treat these tumours. In the past, I’ve used a medication called Somatuline Autogel, which is normally used to treat pituitary adenomas that produce growth hormone. But I’m currently taking a different medicine, called cabergoline. It’s usually used for pituitary tumours that produce prolactin (prolactinomas). I’ve written a Sickly Mama blog post about my experience with this treatment here.

What Was My Experience Of Pregnancy With A Pituitary Tumour?

I’ve written in detail about my experiences of pregnancy and birth with a pituitary tumour in this blog post. Prior to pregnancy, my doctors changed my medication to a medicine that has been used more frequently in pregnant women, and during the pregnancy itself I had regular check-ups and blood tests to monitor my hormone levels. Because the pituitary gland naturally enlarges during pregnancy, my doctors also regularly checked that the enlarged gland plus the TSHoma tumour wasn’t so big that it was pressing on my optic nerve and affecting my vision.

I really wanted to try breastfeeding, but the medication I was taking (cabergoline) actually prevents the production of breastmilk. I therefore stopped taking the medication at 34 weeks, with the plan that this should give me at least four weeks off the medication before the baby arrived, and then I would be able to breastfeed for a couple of months before my symptoms returned and I had to restart the medication. Unfortunately, as Little Man arrived rather earlier than expected at 37 weeks, this didn’t quite work out!

What Was My Experience Of Birth With A Pituitary Tumour?

Again, you can read the full story of my experience of birth with a pituitary tumour in this blog post! My endocrinologists were confident I could have a normal birth, although they did want me to give birth in the hospital birth unit, rather than a midwife-led unit or at home. They also advised that there should be steroids on hand, to be administered if I experienced any unexplained low blood pressure, in which case an adrenal crisis should be suspected. Fortunately they were not needed!