Acromegaly

On this page:

• What is acromegaly?
• How common is acromegaly?
• Is acromegaly the same as gigantism?
• Causes of acromegaly
• Symptoms of acromegaly
• Diagnosis of acromegaly
• Treatment

What is acromegaly?

Acromegaly is a growth disorder caused by the pituitary gland making too much growth hormone. Often, this is because of a benign (non-cancerous) tumour of the pituitary gland. This tumour causes the pituitary gland to make too much growth hormone (GH). As growth hormone is made it is released into the blood. In response, the liver creates another hormone called insulin-like growth factor 1 (IGF-1). IGF-1 triggers tissue growth in the body.  

Acromegaly causes abnormal growth in the body. If you have acromegaly, you may notice your hands and feet becoming larger, or your jaw or face changing shape. These are just some of the symptoms of acromegaly. 

How common is acromegaly?

Acromegaly is a rare condition, with only around 4-6 people per million being diagnosed every year. This means about 1 in every 200,000 people will be diagnosed with acromegaly every year.  

The diagnosis is often delayed as the symptoms develop gradually over time and people with the condition may not notice the changes. People may have had acromegaly for several years before the condition is recognised. 

Acromegaly is usually not passed on from your parents to you (inherited). However, there are rare cases where acromegaly, and other pituitary conditions, have been inherited through families.  

Is acromegaly the same as gigantism?

Acromegaly most commonly occurs in adults aged between 30 and 50 years old, but it can occur at any age. If acromegaly develops before you have stopped growing (which usually occurs between the ages of 15 to 17) it can cause gigantism. This can make someone grow very tall because the excess growth hormone promotes growth of the legs and arms. This doesn’t happen in adults as bones stop growing during puberty, so they are not affected by growth hormone.

The name acromegaly comes from the Greek words for “extremities” (acro) and “great” (megaly). 

Growth hormone has effects on many different parts of the body; in adults it is important to maintain normal energy levels and to keep body tissues, such as muscle and bone, healthy. In children it is essential to reach normal growth. 

What causes acromegaly?

Acromegaly is commonly caused by a benign (non-cancerous) tumour in the pituitary gland. This tumour causes more growth hormone than normal to be made, which causes acromegaly.

If you have been diagnosed with acromegaly caused by a tumour, you may here doctors and clinicians use different names to refer to your tumour. They may use words like “growth”, “adenoma”, or “pituitary neuroendocrine tumour”. These words all refer to a non-cancerous growth in the pituitary gland.

Pituitary neuroendocrine tumours

Your healthcare team may refer to your pituitary tumour as a pituitary neuroendocrine tumour (PitNET). This means a tumour that affects hormone-producing cells, such as the cells in the pituitary gland. The term pituitary neuroendocrine tumour is just another name for pituitary adenoma, which are almost always benign. Some neuroendocrine tumours can be cancerous and occur in other areas of the body, like the lungs and intestines.

It is important to know that whilst a pituitary tumour may be called a neuroendocrine tumour, it is not the same as the cancerous neuroendocrine tumours. If you are worried or do not understand your diagnosis, you should speak to your endocrine team

What are the symptoms of acromegaly?

Symptoms of acromegaly often appear gradually and can progress as the condition progresses. Symptoms can vary and you may not have all of the symptoms listed. Early symptoms can include tiredness and sleep disturbances.  

As the condition progresses, you may notice changes to your facial structure, hands and feet.  

Symptoms can include:

• difficulty sleeping, which may include night sweats and sleep apnoea
• headaches and facial pain
• swollen hands and feet. You may notice a change in ring or shoe size, or wider feet
• lips, nose or tongue getting bigger
• joint pain
• changes to your face, such as brow bone and lower jaw changing shape and sticking out more. Teeth may become more spaced out as the jaw gets bigger
• Sweating more and worsening body odour
• erectile dysfunction
• low sex drive (libido)
• changes to menstrual cycle
• vision changes
• weight gain
• mood swings
• changes to how your voice sounds or how you speak, such as deeper voice or new lisp

You may feel pain in your face if your facial bones are affected. You may also notice changes to your bite, resulting from your jaw changing shape.  

An overgrowth of bone and cartilage can lead to arthritis. As the tissue thickens, it may also put pressure on your nerves, leading to issues like carpal tunnel syndrome, which can cause weakness, numbness and pain in the hands.  

Your internal organs, like your heart and bowel, can also be affected and become larger. 

How is acromegaly diagnosed?

Diagnosis of acromegaly is often delayed for several reasons:

• the symptoms develop slowly and are not always spotted
• symptoms can be confused with other conditions
• the symptoms might not be linked together
• you and your family or friends may not notice the changes

You may have had acromegaly for several years before you are diagnosed.

If you think you may have acromegaly, you should speak to your GP about this. There are some tests your GP can do to find out if you have acromegaly. If your GP suspects you have acromegaly, you should be referred to an endocrinologist. An endocrinologist is someone who specialises in hormone (endocrine) disorders.

It may be helpful to take photos with you to your GP appointment to show any changes in your features. 

What tests are done to diagnose acromegaly?

Blood tests

Some blood tests used to diagnose acromegaly will test the amount of growth hormone and IGF-1 in your blood. People with acromegaly have higher than normal levels of these hormones. However, your pituitary gland makes different amounts of growth hormone at different times of the day, so it can be hard to diagnose acromegaly from just these tests alone.  

A second type of test may also be used, called an oral glucose tolerance test.

Oral glucose tolerance test

This is a test where you are given a drink with glucose (sugar) in it, and then a sample of your blood is taken to see how your hormones respond to this. 

In healthy people, your pituitary gland makes less growth hormone in response to glucose. If you have acromegaly, this will not happen and so your growth hormone levels will stay high. 

MRI scans

You may also have an MRI scan of your pituitary gland, so that doctors can see the size and position of the tumour that is causing your acromegaly. Sometimes, the tumour is too small to see on an MRI, or in very rare cases, the tumour is elsewhere in the body. If this is the case, you may need further MRI or CT scans.

Eye tests

You may also have field of vision tests, to see if the tumour is affecting your eyesight. The pituitary gland sits near the optic nerve, so tumours of the pituitary gland can also sometimes put pressure on this nerve and affect eyesight. A field of vision test will look for any signs of this. 

Blood tests to check other hormones

Other blood tests may be taken to check if any other pituitary hormones are affected by your tumour. You can read more about other pituitary hormones here.

How is acromegaly treated?

Treatment options include surgery, medical therapy and radiotherapy. The goals of treatment are to reduce excess GH, relieve pressure that the growing tumour may be exerting, e.g on the eye nerve, preserve normal pituitary function and improve symptoms of acromegaly.

Studies show that if left untreated people with acromegaly are more likely to suffer from diabetes, high blood pressure and heart problems, as well as having a reduced life expectancy compared to the normal population. These can be improved to normal after the successful treatment of acromegaly.

Surgery

Some people may need surgery to remove the tumour. The operation is usually carried out by making a small cut above the upper teeth behind the upper lip, or through the nose. This is called Trans-sphenoidal Surgery. By going behind the nose like this, the surgeon can see the pituitary gland without having to operate on the main part of the head. In some centres an Endoscopic approach is used – fine tubes called endoscopes are pushed through the back of the nose, involving a small incision.

Most people can be treated very successfully this way, although results are usually better if your tumour is small. The operation takes about an hour and a half. People tend to remain in hospital for three to five days. For the best results it is important to be referred to an experienced pituitary surgeon who operates on 20 or more cases per year.

Surgery will normally lower your growth hormone levels, but in some instances the acromegaly is not cured. In such cases, consideration will be given to treating you further with drug therapy and/or radiotherapy.

Treatment with drugs

There are three types of drugs for treating acromegaly – each act by different mechanisms:

• Somatostatin Analogues work on specialist markers (somatostatin receptors) to inhibit GH release from the pituitary tumour.
• Dopamine Agonists work on alternative markers (dopamine receptors) on the surface of the tumour to inhibit GH release from the tumour by a different mechanism.
• Pegvisomant is a newer drug which works differently and blocks the action of GH and reduces IGF-1 levels.

Somatostatin Analogues

Somatostatin analogues require injections. There are two somatostatin analogues available for the treatment of acromegaly:

• Octreotide (brand name Sandostatin, manufactured by Novartis). Octreolin is an oral formulation of injectable Octreotide
• Lanreotide (brand name Somatuline, manufactured by Ipsen).

Octreotide

Octreotide can be given once a month deep into muscle (intramuscularly) for the long-acting preparation (Sandostatin LAR, Novartis), or, occasionally, three times a day under the skin (subcutaneously).

The short-acting preparation of octreotide is provided as ampoules or vials, which can be used for several doses. It is normally kept in the fridge, but must be removed and come naturally to room temperature before use.

The long-acting preparation is usually given by a nurse at your GP surgery.

Lanreotide

Lanreotide (Somatuline Autogel, Ipsen) is available as a once per month depot injection. A depot injection means it is a slow release medication. It can be given by the patient.

Octreotide and Lanreotide help the symptoms of acromegaly by reducing growth hormone levels into the target range of less than 1.8/2 ug/l in about half of patients.

When you first start taking somatostatin analogues, it may give you stomach colic or diarrhoea, but these effects usually wear off within a few days. Some patients find that stomach problems improve if they do not inject for about two hours after eating. In the longer term both may cause gallstones, but these very seldom cause problems.

Dopamine agonists

There are several dopamine agonists available, all are taken by mouth but only two are widely used:

• Cabergoline (brand name Dostinex, manufactured by Pfizer)
• Bromocriptine (brand name Parlodel, manufactured by Novartis)

Cabergoline, a newer long-acting dopamine agonist that causes fewer side-effects than bromocriptine, appears to be more effective in lowering GH and IGF-I levels, and needs to be taken only twice weekly. It is not licensed for the treatment of acromegaly but is an accepted and widely used treatment. Dopamine agonists used in very high doses to treat Parkinson’s disease have been shown to cause heart valve changes in some patients but studies in patients receiving cabergoline for acromegaly have been reassuring in this respect and no significant heart valve changes have been reported.

Usually people using Cabergoline for pituitary conditions will need to have an echocardiogram (heart scan) at the beginning of treatment. Your endocrinologist or GP will arrange this for you. Bromocriptine usually needs to be taken two or three times a day.

Unfortunately, although dopamine agonists are taken by mouth, they are often less effective than somatostatin analogues which have to be injected. They may cause you to be constipated, although this can be alleviated by increasing the fibre in your diet. At the beginning of treatment, you may also suffer nausea or dizziness when you first stand up. These effects also tend to wear off with time.

Pegvisomant

Pegvisomant (Somavert, Pfizer) is a completely different way of treating acromegaly.

Pegvisomant is a blocker of the action of GH. It does not try to inhibit the release of GH from the pituitary into the blood but instead stops the production of GH.

This should block all the unwanted effects of GH and studies in patients with acromegaly suggest it is very effective. It is given as a daily subcutaneous (under the skin) injection. It is currently used for people where the more traditional treatments have not been successful.

Radiotherapy

Radiotherapy (treatment with radiation) might be needed if not all the tumour could be removed in surgery or if it was not possible for you to have an operation.

You will attend the clinic on two or three occasions to have a special mask or fixation device made. This is a clear plastic mask or device which is used to hold your head still and ensure the radiation beams are correctly aligned.

Radiotherapy will be planned and carried out with extreme care. Using MRI or CT scans the radiotherapy team will spend time planning exactly where the X-rays will be aimed.

Treatment – very low doses of radiation – is usually given through three parts of the head – one on top of your scalp, and one area just in front of each ear.

The treatment itself usually comprises 5 – 6 weeks of daily treatment (Monday to Friday). It may take several months, or even years, after the treatment for the effects of radiotherapy to be complete. While you are waiting for this, you may be given drug treatment to improve control of GH levels.

Improvements in pituitary scanning and computerised control of radiotherapy mean that new forms of finely focused, high dose radiotherapy (stereotactic) are being developed. This treatment is not suitable for all pituitary tumours and its benefit is being evaluated.

Stereotactic radiotherapy allows much higher doses of radiation to be given to a part, or occasionally the whole, of the tumour often in a single session. The larger dose of radiation means that your GH levels come under control much more quickly, maybe after months rather than years. The Gamma Knife, the best-known form of stereotactic radiotherapy, is currently not widely available in the UK.

Effective treatment

Once treatment is successful, you should notice that the soft tissue in your hands and feet decrease in size and patients often notice that their facial features gradually return towards normal.

If you were suffering from excess sweating this should decrease and if you had diabetes mellitus, it should improve, or disappear altogether. Your headaches will usually improve and so will any visual disturbances that may have been present beforehand. If you snored, it should be improved. Some bone growth will usually decrease.