Acromegaly is a condition in which the body produces too much growth hormone, leading to excess growth of body tissues over time.
Typical features include:
- abnormally large hands and feet
- large, prominent facial features
- an enlarged tongue
- abnormally tall height (if it occurs before puberty)
For more, see What are the signs and symptoms?
Acromegaly affects about 6 in every 100,000 adults. The problem is extremely rare in childhood.
Role of growth hormone
Growth hormone is produced and released by the pituitary gland, a pea-sized gland just below the brain.
When growth hormone is released into the blood, it stimulates the liver to produce another hormone – insulin-like growth factor 1 (IGF-1) – which causes growth of muscle, bones and cartilage throughout the body.
This process is essential for growth and repair of body tissues.
What happens in people with acromegaly?
Acromegaly is caused by excessive production of growth hormone after the skeleton and organs have stopped growing. If it occurs before puberty, it leads to excessively tall height and is termed gigantism.
It is usually caused by a benign (non-cancerous) brain tumour, called an adenoma. Read more about benign brain tumours.
The adenoma is rarely inherited – it usually develops spontaneously as a result of a genetic change within a cell of the pituitary gland. This genetic change switches on a signal that tells cells in the pituitary gland to divide and secrete growth hormone.
The tumour may grow to more than 1cm in size and compress the surrounding normal pituitary tissue, which can also affect the production of other hormones, such as thyroid hormones released from the thyroid gland.
What are the signs and symptoms?
Acromegaly typically causes:
- joint aches
- large hands and feet
- carpal tunnel syndrome (compression of the nerve in the wrist, causing numbness and weakness of the hands)
- thick, coarse, oily skin
- skin tags
- enlarged lips and nose
- protruding tongue and brow
- widely spaced teeth
- deepening of the voice due to enlarged sinuses and vocal cords
- sleep apnoea (breaks in breathing during sleep due to obstruction of the airway)
- excessive sweating and body odour
- fatigue and weakness
- impaired vision
- loss of sex drive
- abnormal periods (in women)
- impotence (in men)
- excessive height (if it occurs before puberty)
Some of the above symptoms will be the result of the tumour compressing nearby tissues – for example, headaches and vision problems may happen if the tumour squashes nearby nerves.
These symptoms can occur at any age, but they develop slowly and are often not noticed until middle age. The symptoms are also very non-specific, so the condition may not be diagnosed until a few years after symptoms started.
What you should do
If you think you have acromegaly, see your GP straight away. Acromegaly can usually be successfully treated with brain surgery and medication, but early diagnosis and treatment is important to prevent the symptoms getting worse and to reduce your chance of getting complications.
What are the complications?
If acromegaly is left untreated, you are at risk of the following health problems:
How is it diagnosed?
If your doctor suspects acromegaly from your symptoms, they will order blood tests to measure your levels of human growth hormone and insulin-like growth factor 1 (IGF-1).
Levels of growth hormone naturally vary from minute to minute as it is released from the pituitary gland in spurts. Therefore to accurately diagnose acromegaly, growth hormone needs to be measured under conditions that normally suppress growth hormone secretion.
Your doctor will probably use the glucose tolerance test, as the release of growth hormone is normally suppressed by the presence of glucose in the blood. Drinking glucose solution will not suppress growth hormone levels in people with acromegaly.
Your doctor will also measure your level of IGF-1, which should increase with the level of growth hormone. Elevated IGF-1 levels almost always indicates acromegaly.
You will then have an MRI scan of your brain to locate and define the size of the pituitary gland tumour causing your acromegaly. A CT scan will be done if, for some reason, you are unable to have an MRI scan.
An echocardiogram (a scan that produces moving images of the inside of your heart) may be undertaken to test for an enlarged heart and leaky heart valves.
How is it treated?
Treatment aims to:
- reduce excess growth hormone to normal levels
- relieve the pressure that the tumour is exerting on the surrounding structures
- treat any hormone deficiencies
- improve the symptoms of acromegaly
This is usually achieved through surgical removal of the tumour and medication.
If left untreated, acromegaly can result in serious illness and even death, as the symptoms would get worse and the risk of high blood pressure, diabetes, and cardiovascular disease would increase.
You will probably need surgery to remove the adenoma in your pituitary gland. This usually corrects the growth hormone excess in most patients, although sometimes the tumour is too large to be removed completely.
Under a general anaesthetic, the surgeon will make an incision through your nose or inside your upper lip to access the gland. Removing the tumour promptly relieves the pressure on the surrounding structures and leads to a rapid lowering of growth hormone levels.
Pituitary surgery is usually a successful treatment, providing the tumour isn't too big. Facial appearance and soft tissue swelling improve within a few days.
Possible complications of surgery include damage to the healthy parts of the pituitary gland, leakage of cerebrospinal fluid (which surrounds and protects the brain), and meningitis, though this is rare. Your surgeon will discuss these risks with you and answer any questions you have.
The following medications may be used before or after surgery, or when surgery is not possible:
- Bromocriptine or cabergoline, which suppress growth hormone production. These only work in a small proportion of patients.
- Octreotide or lanreotide, which control growth hormone release and lead to tumour shrinkage in 30-40% of people. They are generally given by an injection into the muscle or under the skin once a month. Studies have shown they are safe and effective for long-term treatment.
- Pegvisomant, given once a day by injection – this directly blocks the effects of growth hormone and can improve symptoms. It lowers IGF-1 but not growth hormone levels – read more about pegvisomant for acromegaly (PDF, 162Kb) .
If surgery is not possible, you may be offered radiation therapy. However, reduction in growth hormone levels after radiation is very slow.
You will either receive:
- conventional radiation – where the tumour is targeted with external beams, this can potentially damage the surrounding pituitary gland and brain tissue, so small doses of radiation are given over four to six weeks, giving normal tissue time to heal in between treatments
- stereotactic delivery – this allows a high-dose beam to be precisely aimed at the tumour, requiring you to wear a rigid head frame to keep your head still, and it can sometimes be done in a single session
Unfortunately, radiation therapy will often cause a gradual decline in the production of other hormones from your pituitary gland, so you'll usually need to take hormone replacement therapy for the rest of your life. There's also a risk it will impair fertility. Speak to your doctor about these risks.
Screening for bowel cancer
Acromegaly increases your risk of bowel cancer, so it is highly recommended that you have regular colonoscopy screening from the age of 40. Find out more about bowel cancer screening.
Most people with acromegaly can be successfully treated. Brain surgery will often return hormone levels to normal, especially if the tumour is less than 1cm in diameter.
With larger tumours, surgery will improve hormone levels, but levels often do not return to normal unless you also take medication.
After treatment, you'll need regular follow-up appointments for the rest of your life with your specialist. These will be used to monitor your pituitary function, check you are on the correct hormone replacement treatment, and to ensure the acromegaly does not return.