What is Gigantism and how is it caused?
Your endocrine system is responsible for the regulation of your body’s metabolism, sexual development, reproduction, sleep, homeostasis, immunity and growth; and there are 8 hormone secreting glands in your body. To find out more about this please see this blog post.
The pituitary gland is the one that manages growth and development so when it produces too much growth hormone (GH) after puberty– usually due to the presence of a benign tumour - this results in Acromegaly
However if this overproduction starts in infancy, childhood or adolescence it results in gigantism. This is much more rare than Acromegaly with an estimated worldwide incidence of 8 per million person-years and with the total number of cases only in the hundreds.
The causes of gigantism
There are actually two main causes of gigantism. The first, as described, is the over production of GH – known as pituitary gigantism and this may either run in families or be as a result from a condition such as:
- Neurofibromatosis Type 1
- McCune –Albright Syndrome
- Multiple Endocrine Neoplasia Type 1
- Isolated Familial Somatotropinomas
- X- Linked Acrogigantism
29% of patients with gigantism are found to have a DNA mutation in what’s called AIP. A study completed in 2017 revealed one in 150 people in Mid Ulster were found to carry this gene as compared to one in 2,000 in the rest of the UK. This gene would have caused “Irish Giant” Charles Byrne to grow to more than 2.3m and was undoubtedly the basis behind the many tales of Irish Giants
The second cause is due to the presence of an overgrowth syndrome such as
- Sotos Syndrome
- Beckwith-Wiedemann Syndrome
- Simpson Golabi-Behemel syndrome
- Weaver Syndrome
The symptoms of gigantism
The main feature of gigantism is excessive height whereas acromegaly features excessive growth of the lower jaw, tongue and finger ends. This excessive height often starts at the age of 13 and may be accompanied by a head circumference that is greater than the 98th percentile or obesity.
The symptoms of gigantism are not dissimilar to acromegaly; both may feature headaches and disturbed vision which is caused by the effect of pituitary tumours. There is also likely to be excess sweating; mild to moderate obesity, osteoarthritis and joint pain
Additional features which are frequently encountered in gigantism include
- A voracious appetite
- Large hands and feet
- A broad bridge to the nose
- A prominent forehead
- A protruding jaw
- High blood pressure
- Type 2 diabetes
- Muscle weakness
- Delayed puberty
The main goal of treatment is to prevent further linear growth.
As in acromegaly there are three types of treatment surgery, radiation or medical therapy (which is usually used alongside surgery/radiation) using either Somatostatin Analogues, Dopamine Agonists or GH Receptor Antagonists.
Unfortunately, complete disease control in a well progressed condition can be difficult to achieve and is only about 50% effective. For this reason - and for improved outcomes - early detection is vital and is dependent upon a blood test to measure growth hormone levels during an oral glucose test and measurement of IGF-1 which indicates excess GH production. An MRI scan of the Pituitary Gland is required and this will usually confirm the presence of a pituitary tumour.
I hope this has been helpful
Although every effort is made to ensure that all health advice on this website is accurate and up to date it is for information purposes and should not replace a visit to your doctor or health care professional.
As the advice is general in nature rather than specific to individuals Dr Vanderpump cannot accept any liability for actions arising from its use nor can he be held responsible for the content of any pages referenced by an external link