Gigantism

Medically Reviewed By William C. Lloyd III, MD, FACS
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What is gigantism?

Gigantism is a very rare condition that occurs during childhood, in which there is extreme bone, muscle and organ growth. Gigantism is caused by an overproduction of growth hormone (GH) that occurs before a child’s bone growth plates have closed. This results in excessive growth and abnormally tall height.

People with gigantism generally have very large hands, fingers, toes and heads. They also have changes in related characteristics, including coarse skin, excessive sweat production, and a very deep voice. They may have enlarged internal organs, such as the heart, kidneys, brain and tongue. This can cause complications, including high blood pressure, severe headaches, sleep apnea, diabetes, diminished vision, and heart failure.

The overproduction of GH that causes gigantism is most often the result of benign pituitary tumors. These press on the pituitary gland, causing it to produce too much GH. In most cases, pituitary gigantism occurs in isolation. In rarer instances, certain inherited or genetic syndromes, such as multiple endocrine neoplasia and McCune-Albright syndrome, can lead to excessive GH production resulting in gigantism.

Acromegaly is a slightly more common disorder that is often grouped with gigantism because it is also caused by overproduction of GH. The main difference between the two disorders is that overproduction of GH in acromegaly occurs in adulthood after the bone growth plates have closed, so it does not result in the same extreme growth as with gigantism. However, many of the other symptoms are the same, including skin and organ changes.

Gigantism is a treatable condition. However, left untreated, gigantism can lead to a variety of complications, such as heart disease, unusual height, delayed puberty, and double vision. Seek regular medical care for your child to reduce the risk that gigantism will develop and progress undetected. Seek prompt medical care if you notice unexplained changes in your child’s appearance, such as excessive growth in height or unusual enlargement of the face, hands or feet.

What are the symptoms of gigantism?

Gigantism is characterized by extreme growth. Children with gigantism are very tall for their age and may also have the following conditions:

  • Enlarged hands, fingers, toes, head or tongue
  • Excessive sweat production
  • Headaches
  • Irregular menstrual periods in teens
  • Late onset of puberty
  • Obesity
  • Production of breast milk (galactorrhea)
  • Unusually large jaw, prominent forehead, and thick facial features
  • Vision distortion, such as double vision and problems with peripheral vision
  • Weakness and tingling in the arms and legs due to enlarging tissues compressing nerves

Symptoms that might indicate a serious condition

The risk of complications of gigantism can be reduced with early diagnosis and treatment. Seek regular medical care for your child to reduce the risk that gigantism will develop and progress undetected. Seek prompt medical care if you notice unexplained changes in your child’s appearance, such as excessive growth in height or any of the above symptoms.

What causes gigantism?

Gigantism is caused by an overproduction of growth hormone (GH) that occurs in childhood before the bone growth plates have closed. Diseases, disorders and conditions that can cause GH overproduction leading to gigantism include:

  • Benign tumors of the pituitary gland, which press on the pituitary gland and cause excessive GH production. This is the most common cause of gigantism.

  • Carney complex (rare gene mutation that causes a high risk of certain tumors including pituitary adenoma)

  • McCune-Albright syndrome (syndrome caused by a gene mutation)

  • Multiple endocrine neoplasia type 1 (inherited disorder that causes tumors to form in endocrine glands and makes them hyperactive)

  • Neurofibromatosis (genetic disorder causing tumor growth)

What are the risk factors for gigantism?

Gigantism is a very rare disorder. The main risk factor for gigantism is having a parent or sibling with gigantism.

How is gigantism treated?

Treatment of gigantism may involve a combination of techniques to reduce or regulate the pituitary gland’s release of growth hormone (GH). The exact treatment plan will vary based on the underlying cause of the overproduction of GH. Your healthcare provider is best able to guide your treatment decisions based on your specific circumstances.

Medical treatments of gigantism

Medications may be used to reduce GH release, block the effects of GH, or prevent growth in stature. They include:

  • Dopamine agonists, such as bromocriptine mesylate (Cycloset, Parlodel) and cabergoline (Dostinex), which reduce

  • GH releaseGH antagonist, pegvisomant (Somavert), which blocks the effects of GH

  • Sex hormone therapy, such as estrogen and testosterone, which may inhibit the growth of long bones

  • Somatostatin analogs, such as octreotide (Sandostatin) and long-acting lanreotide (Somatuline Depot), which reduce GH release

Other treatments of gigantism

Other treatments of gigantism include:

  • Radiation of the pituitary gland to regulate GH. This is generally considered the least desirable treatment option because of its limited effectiveness and side effects that can include obesity, emotional impairment, and learning disabilities

  • Surgery to remove a pituitary tumor, which is the treatment of choice for well-defined pituitary tumors

What are the possible complications of gigantism?

Complications of gigantism can be serious. You can help minimize your risk of serious complications of gigantism by following the treatment plan your healthcare professional designs specifically for you or your child. Complications of gigantism include:

  • Delayed puberty

  • Diabetes and other endocrine disturbances

  • Difficulty functioning in everyday life due to large size and unusual features

  • Diminished vision or total vision loss

  • Embarrassment, isolation, difficulties with relationships, and other social problems

  • Hypothyroidism

  • Severe chronic headaches

  • Sleep apnea

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Medical Reviewer: William C. Lloyd III, MD, FACS
Last Review Date: 2021 Jan 10
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THIS TOOL DOES NOT PROVIDE MEDICAL ADVICE. It is intended for informational purposes only. It is not a substitute for professional medical advice, diagnosis or treatment. Never ignore professional medical advice in seeking treatment because of something you have read on the site. If you think you may have a medical emergency, immediately call your doctor or dial 911.
  1. Carney complex. Genetics Home Reference. http://ghr.nlm.nih.gov/condition/carney-complex
  2. Gigantism. PubMed Health, a service of the NLM from the NIH. http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0002157/
  3. Acromegaly. National Institute of Diabetes and Digestive and Kidney Diseases. http://www.endocrine.niddk.nih.gov/pubs/acro/acro.htm
  4. Sotos, JF. Overgrowth. Hormonal Causes. ClinPediatr. 1996;35(11):579-90
  5. Keil MF, Stratakis CA. Pituitary tumors in childhood: update of diagnosis, treatment and molecular genetics. Expert Rev Neurother 2008; 8:563
  6. Pizzo PA, Poplack DG (Eds), Principles and Practice of Pediatric Oncology, Lippincott Williams & Wilkins, Philadelphia 2011