What is gigantism?

Gigantism is a very rare condition. It causes children to grow faster than normal and grow very tall. There is treatment for gigantism. Some affected children may still have symptoms after treatment. They need regular check-ups with their doctor as they grow.

What are the symptoms of gigantism?

Gigantism can appear in a child of any age, from baby to teenager.

The main symptom is faster than normal growth. This means that your child will be unusually tall for their age. They can also have:

• a large head
• a very noticeable forehead
• a jaw that seems to jut out
• unusual features of the face, such as a broad nose
• very large hands and feet, with thick fingers and toes
• more sweating than usual
• a very large appetite
• general weakness

Some people also get headaches or a sick feeling in their stomach. Some may have problems with their eyesight or are slow to get to puberty.

What causes gigantism?

The way the body grows through life is controlled by hormones. These hormones are made by the pituitary gland in the brain. The most important hormone for growth is called growth hormone (GH). Another name is human growth hormone (HGH).

Most children with gigantism make too much growth hormone. This causes them to grow too much, and too fast.

Gigantism is almost always caused by a benign tumour. The type of tumour is called an adenoma. It grows in the pituitary gland. There is usually no clear reason why the adenoma occurs. In rare cases, it may be due to a genetic health issue.

In other cases rare genetic conditions can cause gigantism without your child having an adenoma. Examples include Sotos syndrome, Beckwith-Wiedemann syndrome, and Weaver syndrome.

Adults can develop a similar condition to gigantism. It is called acromegaly. Acromegaly also causes growth that is not normal, but it does not make the person grow taller. It causes other symptoms, such as changes to features of the face. It can also lead to larger than normal hands and feet.

How is gigantism diagnosed?

A doctor who notices that a child is growing unusually fast will do a physical examination. The doctor will ask questions and check your child’s height, weight, and body proportions. They will also test your child’s senses such as their eyesight and hearing. They may test for the stage of puberty of the child.

Tests to diagnose gigantism include:

• Blood tests — to measure hormone levels, and test for other health issues.
• Oral glucose tolerance test — to see how growth hormone levels change when blood sugar level is increased.
• An MRI or CT scan — to look at the pituitary gland.
• X-rays of the skull and jaw — to check bone thickness.

It is very important to test for gigantism if your child has signs of the condition.

How is gigantism treated?

Treatment for gigantism should begin as early as possible. If there is no treatment, the child may develop serious health issues. Problems like diabetes, high blood pressure and arthritis can result if there is no treatment.

Treatments for gigantism include:

• Surgery — to remove or shrink the pituitary tumour.
• Radiotherapy — to slow the growth of the tumour and lower the levels of growth hormone.
• Drug therapy — to control levels of growth hormones, ease symptoms, and shrink the tumour.

Can gigantism be prevented?

Unfortunately, there's nothing you can do to prevent gigantism.

Complications of gigantism

Children with gigantism can lead a normal life. If they are treated successfully, they will not get most of the serious complications.

However, children with gigantism can still have symptoms such as muscle weakness. Others may have psychological problems. It can be hard to buy items such as clothes and shoes.

Regular checks with the doctor are needed throughout the person’s life. This can help find any problems early.

Resources and support

If you want to know more about gigantism, talk to your doctor or call healthdirect on 1800 022 222 (known as NURSE-ON-CALL in Victoria). A registered nurse is available to speak to, 24 hours, 7 days a week.