Gigantism: Symptoms, Causes, Diagnosis, Treatment and Outlook

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Illustration of a man who have Gigantism

1Overview

The endocrine system plays a pivotal role in the body. It helps produce, release and control the hormones for various body processes. If the endocrine system goes in mayhem, it may lead to various health conditions and even life-threatening scenarios.

The pituitary gland, for instance, is a gland responsible for the release of several hormones, including the growth hormone (GH) also called somatotropin.
This hormone is responsible for making people grow tall or bigger. When the production goes out of control and releases too much growth hormone, it may lead to a condition dubbed as gigantism.

Gigantism is a serious health condition caused by an adenoma or tumor in the pituitary gland. It occurs in patients who had experienced an excessive production of growth hormone in childhood. This happens when the tumor cells in the pituitary gland release too much growth hormone, leading to various changes in the body.

This is a rare condition which can also result in abnormal growth in children. This is the most noticeable effects on kids, which include changes in the child’s height and girth.
Early detection and diagnosis of gigantism are important to prevent the abnormal growth of children. Prompt and appropriate treatments are needed to stop or slow the changes that might happen and the child from growing larger than normal.

2Symptoms

In 90 percent of all patients with gigantism, the overproduction or excessive growth hormone levels is caused by a benign tumor of the pituitary gland dubbed as an adenoma.

The tumor can lead to the excessive production of GH as it spreads or grows. Aside from the visible signs of gigantism in the body, there are other symptoms such as headaches and visual disturbances.

These are caused by the tumor’s growth, compressing the surrounding neural tissues such as the optic nerves. Aside from that, the adenoma will also compress the pituitary gland itself, leading to the uncontrolled production of other pituitary hormones.

The symptoms of gigantism may become hard to detect at first because they may seem as if the child just has growth spurts. However, the most common signs and symptoms that may signal gigantism include:

  • The child is much larger than other children of the same age
  • Body parts become larger in proportion to other parts
  • Thick fingers and toes
  • Very large feet and hands
  • Prominent lower jaw protrusion
  • Prominent forehead
  • Coarse facial features
  • Large heads, lips, noses, and tongues

The other signs and symptoms include:

  • Delay in puberty
  • Spreading teeth
  • Pronounced underbite
  • Deepening of the voice in males
  • Arthritis
  • Headache
  • Increased tissue in wrists (nerve compression i.e. carpal tunnel syndrome)
  • Excessive sweating
  • Weakness
  • Insomnia and other sleep disorders
  • Irregular menstrual periods in women
  • Deafness

Signs and symptoms of serious conditions related to untreated or long-standing gigantism:

  • High blood pressure
  • Heart diseases such as heart failure and heart enlargement
  • Type 2 diabetes mellitus
  • People with gigantism are also at a higher risk of developing thyroid cancer and colon polyps
  • Cardiomyopathy
  • Sleep apnea
  • Goiter
  • Osteoarthritis
  • Carpal tunnel syndrome
  • Uterine fibroids
  • Hypopituitarism or decreased production and secretion of other pituitary glands
  • Loss of vision

3Causes

Gigantism is always caused by a benign (noncancerous) adenoma found in the pituitary gland. An adenoma causes the secretion of excessive amounts of growth hormone. The long-term secretion of too much growth hormone may accelerate muscle, bone and connective tissue growth in children and adolescents. As a result, there is increased height and changes in other soft tissues.

Gigantism is almost the same as acromegaly, which is both caused by the prolonged overproduction of GH by the pituitary gland. However, in acromegaly, the acromegaly may be caused by tumors of the lungs, pancreas and adrenal glands.

When the adenoma causes the overproduction of GH, the hormones are then secreted into the bloodstream, causing the production of another hormone, which is found in the liver. The hormone, called insulin-like growth factor 1 (IGF-1), is the culprit in most of the body changes in people with gigantism.

Aside from the several body changes, excess GH may lead to alterations in the sugar and lipid metabolism, increasing the risk of other serious systemic diseases such as diabetes and heart disease.

4Diagnosis

Aside from the needed complete neurological exam and medical history, many diagnostic procedures can be used to determine or detect gigantism.

Imaging tests

Serial photos of the patient can be taken periodically to examine the changes in his or her appearance. These photos can be done through several imaging tests such as the X-ray, magnetic resonance imaging (MRI), and computed tomography (CT scans).

These imaging tests, particularly the CT scan and MRI can also be used to visualize the adenoma and the pituitary gland. These imaging tests are used to locate the tumor in the brain, identify its size and characteristics and detect any possible invasion into other neurovascular structures.

Blood Tests

A blood test is used to determine the high levels of growth hormones in the body. This test will confirm the diagnosis. The test, which will show increased or high levels of both the growth hormone and the insulin-like growth factor 1 (IGF-1).

Since the GH hormone is released in short bouts, the single increased level of growth hormone is not enough to make a diagnosis. Sometimes, the doctors will give a sugar or glucose drink to suppress the levels of the growth hormone. A test called an oral glucose tolerance test is done to see that normal suppression of the hormone does not happen.

5Treatment

The treatment of gigantism may depend on some factors like the size and location of the tumor and the medical condition or age of the patient. The treatment of pituitary adenomas may need the expertise of many specialists for the management of the condition.

The goals of treatment are to decrease or slow the production of growth hormones, to return the GH levels to normal, reverse or ameliorate the effects of gigantism, preserve the other functions of the pituitary gland and relieve the pressure of the adenoma on the pituitary gland and surrounding tissues.

Here are the treatment options for gigantism.

Surgery

Surgery entails the removal of the tumor or adenoma in the brain. This treatment option is preferred if the underlying cause of gigantism is the adenoma. Surgery is the best form of treatment and it cures about 80 percent of the gigantism cases.

Usually, the doctor will operate on the nose, then small cameras are used to visualize the tumor in the pituitary gland.

Pharmacological Treatment

Some medicines are used to treat gigantism. Drug therapy is used to decrease the growth hormone levels. The most effective drugs prescribed by a doctor are those that are forms of somatostatin, the hormone that usually blocks growth hormone production and release.

Octreotide or lanreotide – These drugs are synthetic forms of the somatostatin, which can stop the release of growth hormones in the pituitary gland. These injections are typically administered monthly to suppress the growth hormone production in about 70 percent of patients. In about 30 to 50 percent of the patients, there was a significant decrease of the tumor.

Pegvisomant – This is a new drug that can block the action of GH, which in turn, will decrease the levels of IGF-1 levels in the body. This drug is administered subcutaneously.

Bromocriptine and cabergoline – These are the drugs that come from dopamine agonists, which can lower IGF-1 and GH levels in about 50 percent of the people treated. These are less expensive that octreotide and no injection is needed.

Radiation therapy

For some patients, surgery or medicines are not enough to control gigantism. In these cases, the doctors may recommend using radiation therapy or stereotactic radiosurgery, a technique in which a highly-focused radiation beam is introduced to the tumor. This will eventually reduce the levels of GH and IGF-1 levels for about 18 months.

Another type of radiation therapy is the Gamma knife radiosurgery, wherein a “gamma knife” is used to target the tumor without harming the surrounding tissue. The power of the dose is sufficient to destroy the tumor. However, it will take years to be fully effective. The procedure is performed on an outpatient basis, but with the use of general anesthesia. However, there are side effects of the procedure including obesity, emotional issues and learning disabilities in children.

Hence, this procedure is just done when all other procedures did not work. It’s a last resort choice of treatment for gigantism.

6Outlook

If left untreated, gigantism may result to various complications, such as progressive cosmetic and physical deformities. In some cases, it may lead to serious diseases like hypertension, heart disease, and diabetes mellitus. There is also a heightened risk of heart problems, colon polyps, and premature death.

However, about 80 percent of gigantism cases are treated and cured with surgery. If the tumor comes back after surgery, medicines can be used to treat the condition and reduce the symptoms felt. Hence, with the proper treatment and health care, the condition can be controlled and the children can live a long and fulfilling life. Moreover, with early treatment, the risk of developing physical changes are slowed or stopped.