GIGANTISM
Gigantism is a rare condition characterized by exaggerated bone growth and an abnormal increase in height significantly above average.
- This condition occurs in childhood before the fusion of the bones growth plate which is usually seen at some point after puberty.
- The growth plate is the area of active, soft growing tissues near the ends of the long bones in children and adolescents. Adults do not have growth plates.
- Most long bones have two growth plates; one at each end. They are found in many places including the thigh, hand, and forearm.
- During adolescence when growth is complete, the growth plates harden into solid bones.
- This happens around age 13-15 in girls and age 15-17 in boys.
- For people with gigantism, there is excessive growth during childhood, before the growth plate closes or hardens.
- Gigantism should not be confused with acromegaly, the adult form of the condition, marked by an increase in bone size, including those of the hand, feet, and face.
CAUSES
The most common cause of gigantism is a benign pituitary gland tumor. The pituitary gland is a small gland located at the base of the brain behind the bridge of the nose. The pituitary gland makes the hormones that control so many functions in the body including growth, metabolism, temperature, urine production, and sexual development.
A tumor on the pituitary gland causes it to produce excess growth hormone than the body needs. This subsequently leads to abnormal growth of soft tissues and skeleton.
Other less common cause of gigantism includes:
- Neurofibromatosis, an inherited disorder that causes tumors in the nervous system.
- Multiple endocrine neoplasia type 1 (MEN -1), an inherited condition that causes tumors in the pituitary gland, pancreas, or parathyroid gland.
- Carney complex, that causes gland abnormalities as well as an abnormal growth in bone tissues
- McCune-Albright syndrome, a genetic disease that affects the bone and skin pigmentation.
SYMPTOMS
Symptoms depend on the size of the tumor and may include:
- Tall stature
- Mild to moderate obesity
- Exaggerated growth of feet and hand
- Coarse facial feature
- Thick toes and fingers
- Headaches which may be severe or recurrent
- Visual changes
- An irregular menstrual period in girls
- Deafness
- Weakness
- Delayed puberty in both boys and girls
- Nausea
- Excessive sweating
DIAGNOSIS AND TREATMENT
If gigantism is suspected, the doctor may carry out a blood test to measure the level of growth hormones, and insulin growth factor (IGF-1) produced by the liver. Elevated levels of these hormones suggest gigantism.
An oral glucose test may also be recommended. During this test, the child’s blood levels of growth hormone are measured before and after taking a special beverage containing glucose. Normally, the ingestion of glucose reduces the growth hormone levels. In gigantism, the level will tend to remain the same, indicating that the body is producing too much growth hormone.
If gigantism is diagnosed, imaging tests such as MRI scan of the pituitary gland will be carried out to find the tumor, its size, and location.
TREATMENT
The goal of treatment is to lower or stop the production of the growth hormone and reduce the negative effects of the tumor on the pituitary gland and tissues around it.
Treatment options include:
Surgery to extract or remove the pituitary tumor.
Medications including octreotide or lanreotide usually given as an injection, dopamine agonists such as cabergoline and bromocriptine which are given in pill form, and growth hormone antagonist including pegvisomant.
Radiation to destroy tumor cell and reduce the growth hormone levels.