What is gigantism?

Gigantism, also called pituitary gigantism, is a very rare condition in which a child has high levels of growth hormone, causing abnormal growth, especially in height. The effects of gigantism begin in childhood, before the growth plates in the bones fuse at the end of puberty. (When the production of excess growth hormone begins after the growth plates have fused, the condition is known as acromegaly.) Early diagnosis and treatment can prevent or reduce adverse effects of gigantism.

Signs and symptoms of gigantism

The main sign of gigantism is excessive growth. A child with gigantism grows quickly and is larger than peers of the same age

Other symptoms may include:

• Unusually large hands and feet
• Wide fingers and toes
• Unusually prominent jaw and forehead
• Coarse facial features (enlarged nose, lips and tongue)
• Gaps between the teeth
• Excessive sweating
• Joint pain
• Muscle weakness
• Severe or recurring headaches
• Delayed puberty
• Irregular menstruation
• Enlarged heart and other organs

Causes of gigantism

Growth hormone is produced by the pituitary gland, a pea-sized gland located at the base of the brain. Growth hormone in the blood acts as a signal to the liver to produce another hormone, insulin-like growth factor (1 IGF-1), which drives bone and tissue growth. In most cases, gigantism is caused by a benign adenoma or growth (noncancerous) pituitary tumor. In some cases, the condition is caused by an enlarged pituitary gland, without a tumor.

Genetic mutations can be associated with the formation of pituitary tumors leading to gigantism. The most common of these are mutations or deletions of the AIP gene.

Gigantism can also be associated with other rare genetic disorders, including:

• Carney complex
• McCune-Albright syndrome
• Multiple endocrine neoplasia type 1 (MEN-1)
• Neurofibromatosis type 2 (NF2)
• Familial isolated pituitary adenomas (FIPA)

How is gigantism diagnosed?

If gigantism is suspected, based on excessive height and other symptoms, your doctor may refer you to an endocrinologist, who will:

• Take a complete medical history to understand the occurrence of symptoms
• Perform a physical exam

The endocrinologist may also:

• Order blood tests to check for high levels of growth hormone. These tests may include:
  • Growth hormone and insulin-like growth factor (1 IGF-1) blood tests
  • An oral glucose tolerance test (OGTT), which can detect the presence of a pituitary tumor
• Order imaging studies, such as magnetic resonance imaging (MRI) or computed tomography (CT) to determine the size and location of a pituitary tumor, or a bone age X-ray

Treatment for gigantism

Treatment for gigantism focuses on:

• Controlling elevated levels of growth hormone and insulin-like growth factor
• Managing the pituitary tumor growth 
• Addressing the effects of excessive growth hormone on other body systems
• Addressing any effects of pituitary tumor growth on nearby brain and nerve structures

Treatment may include:

• Surgery to remove a pituitary tumor. Surgeons may reach the tumor through an incision in the upper lip or at the bottom of the nose, or by cutting through the skull.
• Drug therapy to control the over-production of growth hormones or reduce their effect on receptor cells.
• Radiation therapy to kill tumor cells or to keep them from growing. Radiation therapy for a pituitary tumor must be narrowly targeted to minimize damage to nearby brain tissue.

Follow-up care

Patients with gigantism will need regular follow-up visits with their primary doctor or endocrinologist to check that hormone levels are maintained in a healthy range and manage any complications related to the condition. Complications can include hypertension, cardiomyopathy, obstructive sleep apnea and joint problems.

Treatment of gigantism at Children’s Hospital of Philadelphia (CHOP) is managed by Neuroendocrine Center, a multidisciplinary center created to treat children with conditions that require expertise from the Division of Endocrinology and Diabetes, Neurosurgery, Neuro-oncology, Neuro-ophthalmology and Neuroradiology.

If needed for care, the Neuroendocrine Center also collaborates with specialists from Genetics, Pathology, the Cancer Survivorship Program, the Growth Center, the Adrenal and Puberty Center and the Healthy Weight Program. We also work closely with colleagues from the Hospital of the University of Pennsylvania’s Pituitary Center, who focus on pituitary disease in adults. 

Outlook

The long-term outlook for patients with gigantism depends on how soon they are diagnosed and begin treatment, how effective the treatment is in reducing hormone levels and the presence of complications related to the condition. In general, early diagnosis and treatment lead to better outcomes and fewer complications.