What is Gigantism?
Gigantism is a rare condition that causes abnormal growth in children. It occurs when a child’s body produces too much growth hormone.
Early diagnosis is important. Prompt treatment can stop or slow the changes that may cause a child to grow larger than normal. However, the condition can be hard for parents to detect, since symptoms of gigantism might first be seen as normal childhood growth spurts.
What Causes Gigantism?
A pituitary gland tumor is almost always the cause of gigantism. The pea-sized pituitary gland—located at the base of your brain—makes hormones that control many functions in your body. Some tasks managed by the gland include temperature control, sexual development, growth metabolism, and urine production. When a tumor grows on the pituitary gland, the gland makes more growth hormone than the body needs.
Other less common causes of gigantism may include:
- McCune-Albright syndrome: a disease that causes abnormal growth in bone tissue, patches of light-brown skin, and gland abnormalities
- Carney complex: an inherited condition that causes non-cancerous tumors on the connective tissue, cancerous or non-cancerous endocrine tumors, and spots of darker skin
- multiple endocrine neoplasia type 1: an inherited disorder that causes tumors in the pituitary gland, pancreas, or parathyroid glands
- neurofibromatosis: an inherited disorder that causes tumors in the nervous system
Recognizing the Signs of Gigantism
If your child has gigantism, you may notice that he or she is much larger than other children of the same age. Also, some parts of the body may be larger in proportion to other parts.
Common symptoms include very large hands and feet, a thickening of toes and fingers, a prominent jaw and forehead, and coarse facial features. Children with gigantism may also have flat noses and large heads, lips, or tongues.
The symptoms your child experiences may depend on the size of the pituitary gland tumor. As the tumor grows, it may press on nerves in the brain. Many people experience headaches, vision problems, or nausea from tumors.
Other symptoms of gigantism may include:
- excessive sweating
- delayed puberty in both boys and girls
- irregular menstrual periods in girls
How is Gigantism Diagnosed?
If your child’s doctor suspects gigantism, he or she may recommend a blood test to measure levels of growth hormones and an insulin-like growth factor (called IGF-1), which is a hormone produced by the liver.
The doctor also may recommend an oral glucose tolerance test. For this test, your child will drink a special beverage containing glucose, a type of sugar. Blood samples will be taken before and after your child drinks the beverage. In a normal body, growth hormone levels will drop after eating or drinking glucose. If your child’s levels remain the same, it means his or her body is producing too much growth hormone.
If the blood tests indicate a pituitary gland tumor, your child will need a magnetic resonance imaging (MRI) scan of the gland. Doctors use the scan to see the size and position of the tumor.
How is Gigantism Treated?
Treatments for gigantism aim to stop or slow your child’s production of growth hormones.
Removing the tumor is the preferred treatment for gigantism, if that is the underlying cause.
The surgeon will reach the tumor by making an incision in your child’s nose. Microscopes or small cameras may be used to help the surgeon see the tumor in the gland. In most cases, your child should be able to return home from the hospital the day after the surgery.
If surgery is not an option, your child’s doctor may recommend medication. This treatment is meant to either shrink the tumor or stop the production of excess growth hormone.
Your doctor may use the drugs octreotide or lanreotide to prevent the growth hormone’s release. According to the Mayo Clinic, these drugs mimic another hormone that stops growth hormone production (Mayo Clinic, 2010). Most often, these drugs are given as an injection about once a month.
To shrink a tumor before surgery, bromocriptine and cabergoline can be used. These are typically given in pill form. They may be used with octreotide injections, which will also lower the levels of growth hormones and IGF-1.
In situations where these drugs are not helpful, daily shots of pegvisomant might be used as well. Pegvisomant blocks the effects of the growth hormones, but it does not lower the levels of growth hormones in the body or shrink the tumor.
Gamma Knife Radiosurgery
A gamma knife radiosurgery is an option if your child’s doctor believes that a traditional surgery is not possible.
The “gamma knife” is a collection of highly focused radiation beams. These beams do not harm the surrounding tissue, but they are able to deliver a powerful dose of radiation at the point where they combine and hit the tumor. This dose is enough to destroy the tumor.
Gamma knife treatment takes years to be fully effective and return the levels of growth hormone to normal. It is performed on an outpatient basis under general anesthetic. However, since the radiation used has been linked to obesity, learning disabilities, and emotional issues in children, it is usually used only when other treatment options fail.
Long-Term Outlook for Children With Gigantism
According to St. Joseph’s Hospital and Medical Center, 80 percent of gigantism cases are cured with surgery (St. Joseph).
If the tumor returns or if surgery cannot be safely attempted, medications can be used to reduce your child’s symptoms and allow him or her to live a long and fulfilling life.