Gigantism is a rare condition that causes abnormal growth in children. This change is most notable in terms of height, but girth is affected as well. It occurs when your child's pituitary gland makes too much growth hormone, which is also known as somatotropin.
Early diagnosis is important. Prompt treatment can stop or slow the changes that may cause your child to grow larger than normal. However, the condition can be hard for parents to detect. The symptoms of gigantism might seem like normal childhood growth spurts at first.
What causes gigantism?
A pituitary gland tumor is almost always the cause of gigantism. The pea-sized pituitary gland is located at the base of your brain. It makes hormones that control many functions in your body. Some tasks managed by the gland include:
· sexual development
· urine production
When a tumor grows on the pituitary gland, the gland makes far more growth hormone than the body needs.
There are other less common causes of gigantism:
· McCune-Albright syndrome causes abnormal growth in bone tissue, patches of light-brown skin, and gland abnormalities.
· Carney complex is an inherited condition that causes noncancerous tumors on connective tissue, cancerous or noncancerous endocrine tumors, and spots of darker skin.
· Multiple endocrine neoplasia type 1 (MEN1) is an inherited disorder that causes tumors in the pituitary gland, pancreas, or parathyroid glands.
· Neurofibromatosis is an inherited disorder that causes tumors in the nervous system.
Recognizing the signs of gigantism
If your child has gigantism, you may notice that they're much larger than other children of the same age. Also, some parts of their body may be larger in proportion to other parts. Common symptoms include:
· very large hands and feet
· thick toes and fingers
· a prominent jaw and forehead
· coarse facial features
The symptoms your child has 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 in this area. Other symptoms of gigantism may include:
· severe or recurrent headaches
· delayed puberty in both boys and girls
· irregular menstrual periods in girls
How is gigantism diagnosed?
If your child's doctor suspects gigantism, they may recommend a blood test to measure levels of growth hormones and insulin-like growth factor 1 (IGF-1), which is a hormone produced by the liver. The doctor also may recommend an oral glucose tolerance test.
During an oral glucose tolerance 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 their body is producing too much growth hormone.
If the blood tests indicate gigantism, your child will need an MRI scan of the pituitary gland. Doctors use this scan to find the tumor and see its size and position.
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 it's 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.
In some cases, surgery may not be an option. For example, if there's a high risk of injury to a critical blood vessel or nerve.
Your child's doctor may recommend medication if surgery is not an option. 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. These drugs mimic another hormone that stops growth hormone production. They're usually given as an injection about once a month.
Bromocriptine and cabergoline are drugs that can be used to lower growth hormone levels. These are typically given in pill form. They may be used with octreotide. Octreotide is a synthetic hormone that, when injected, can 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 is a drug that blocks the effects of growth hormones. This lowers the levels of IGF-1 in your child's body.
Gamma knife radiosurgery
Gamma knife radiosurgery is an option if your child's doctor believes that a traditional surgery isn't possible.
The "gamma knife" is a collection of highly focused radiation beams. These beams don't harm the surrounding tissue, but they're 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 months to years to be fully effective and to return the levels of growth hormone to normal. It's performed on an outpatient basis under general anesthetic.
However, since the radiation in this type of surgery has been linked to obesity, learning disabilities, and emotional issues in children, it's usually used only when other treatment options don't work.
Long-term outlook for children with gigantism
According to St. Joseph's Hospital and Medical Center, 80 percent of gigantism cases caused by the most common type of pituitary tumor are cured with surgery. If the tumor returns or if surgery cannot be safely attempted, medications can be used to reduce your child's symptoms and to allow them to live a long and fulfilling life.