The pituitary gland, located in the skull base, produces the growth hormone (GH). This gland produces or secretes a total of eight hormones. Apart from the growth hormone (GH), the other hormones secreted control the activity of the thyroid gland and the body temperature. GH performs various functions in the body, like promoting bone and muscle growth, controlling body fluids, regulating sugar and fat levels, and maintaining heart function.

What Is Gigantism?

Gigantism, also known as pituitary gigantism or pediatric acromegaly, is a rare condition in which the pituitary gland produces excess amounts of GH, which makes the child grow very tall when compared to peers. A tumor in the pituitary gland can trigger gigantism. GH, or somatotropin, stops increasing the height once the bones get fused at a certain age. Instead, it focuses on maintaining normal cartilage and bone structure. In gigantism, large amounts of GH cause a continued growth of bone, cartilage, and other soft tissues, which, when left untreated, can make the child attain a height of almost eight inches.

How Is Gigantism Different From Acromegaly?

In both gigantism and acromegaly, there is an excess production of GH. However, acromegaly affects adults, whereas gigantism affects children and teenagers. When there is an excess GH secretion before the bones fuse, it causes gigantism, and when it occurs after the bony plates have fused, it causes acromegaly. Gigantism is rare when compared to acromegaly.

How Common Is Gigantism?

Gigantism is an extremely rare condition that affects boys more when compared to girls.

What Are the Causes of Gigantism?

The primary cause of gigantism is a pituitary tumor called a pituitary adenoma, which is 10 mm (millimeters) or more in diameter. In addition, changes in the AIP gene can cause tumors in children.

The other genetic conditions that can form tumors in the pituitary gland, leading to increased production of GH, include:

McCune-Albright Syndrome: It is a disorder that affects skin, bones, and hormones, impacting growth and puberty.
Carney Complex: It is a disorder with an increased risk of developing different types of tumors.
Type 1 and Type 4 Multiple Endocrine Neoplasia: Genetic disorders in which the endocrine glands have an increased tendency to develop tumors.
Neurofibromatosis: It is a condition that affects the nervous system and skin. There is a growth of tumors all over the body, along the nerves, beneath the skin.
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Pituitary Adenoma - Types, Causes, Symptoms, Diagnosis, and Treatment
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Facial Hemihypertrophy - Types, Causes, Symptoms, Diagnosis and Treatment

What Are the Symptoms of Gigantism?

In children affected with gigantism, there is an increase in height and a growth of muscles and organs. However, excessive growth makes the child look bigger when compared to their peers. Apart from increased growth, the other symptoms may occur due to pressure on the surrounding structures caused by the growing tumor.

The physical characters noted in children with gigantism include:

A rapid increase in height.
Prominent forehead and jaws.
Thick facial features.
Formation of gaps between the teeth.
Large hands and feet.
Thick fingers and toes.

Other symptoms that are noted in gigantism include:

Headache.
Joint pains.
Vision problems.
Excessive sweating.
Enlargement of organs like the heart.
Delay in puberty.
Irregular menstrual cycles.
Weakness of muscles.
Sleep disorders like insomnia and sleep apnea, where breathing gets interrupted during sleep.
Breast milk release.

What Are the Complications of Gigantism?

The common complication that occurs in patients with gigantism is hypopituitarism or a decrease in the function of the pituitary gland due to treatment procedures like surgery and radiation. As the pituitary gland produces many hormones, hypopituitarism can cause an imbalance in the hormonal levels, causing complications.

Complications that occur due to the surgery done to remove the pituitary gland can include bleeding, salt and water imbalance in the body, meningitis (an infection of the protective coverings of the brain), cerebrospinal fluid (CSF) leak (leakage of the fluid surrounding the brain and spinal cord).

Complications due to radiation therapy include loss of fertility, brain injury, loss of vision, and regrowth of tumors.

How Is Gigantism Diagnosed?

As gigantism is a rare condition, diagnosis can be difficult. Also, there may be a variation in the growth patterns of different children. Therefore, doctors may suggest specific blood tests and imaging tests after taking a medical and family history and doing a physical examination. The following tests help in diagnosing gigantism, which include:

Growth Hormone And IGF-1 (Insulin-Like Growth Factor 1) Tests: Determine the levels of GH and IGF-1 in blood. GH is released by the pituitary gland, whereas the liver secretes IGF-1. Elevated values of the above parameters indicate gigantism.
Oral Glucose Tolerance Test (OGTT) Test: Helps understand how the GH levels react to blood glucose in the body. The child has to drink a glucose solution, and the blood sugar levels are measured at regular intervals.
Imaging Tests: Like MRI (magnetic resonance imaging) scans and CT (computed tomography) are done to determine the size and location of pituitary tumors.
Other Tests: To check if other body parts are affected include:
- ECG (Echocardiogram): This checks heart problems.
- X-Rays or Dexa (Dual-Energy X-Ray Absorptiometry) Scan: To check bone health.
- Sleep Tests: Help determine sleep apnea.

How Is Gigantism Managed?

The aim of treatment is to reduce or stop the production of excess GH by the child. The various options for treatment include:

1) Surgery:

Surgery is the preferred mode of treatment in cases where gigantism occurs due to a pituitary tumor. The surgeon removes the tumor by a minimally invasive technique. Microscopes or cameras can view the tumor while performing the surgery. Also, the child can return home a day after the surgery.

2) Medications:

Medications are considered in cases where surgery is not an option. Drugs shrink tumors or decrease the release of GH.

Octreotide or Lanreotide are medicines that prevent the release of GH, which are given as injections once every month. Bromocriptine and Cabergoline are the drugs used in pill form that act by lowering the GH hormone levels in the body. These medicines can be used in combination with Octreotide.

In conditions where the above drugs do not work, daily injections of Pegvisomant help decrease the effects of GH on the body. It also helps lower IGF-1 levels in the body.

3) Gamma Knife Radiosurgery: This is an option only when other treatments do not work. A collection of highly focused beams of radiation are passed onto the area of the tumor. These beams effectively destroy the tumor and do not harm the nearby structures. However, months or years of treatment may be necessary to successfully eliminate the tumor. Also, children receiving this therapy have side effects like obesity, emotional disturbances, and learning problems.

Conclusion:

Gigantism is an extremely rare condition that is caused mainly due to tumors in the pituitary gland. Early diagnosis and the start of treatment are pivotal in achieving better results. Surgery is the most preferred option for managing the condition. However, in cases where surgery is contraindicated, gigantism can be managed with medications, which reduce the symptoms and help the child lead a healthy and happy social life.