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Gigantism is abnormally large growth due to an excess of growth hormone during childhood, before the bone growth plates have closed.

Giantism

The most common cause of too much growth hormone release is a noncancerous (benign) tumor of the pituitary gland. Other causes include:

• Carney complex
• McCune-Albright syndrome (MAS)
• Multiple endocrine neoplasia type 1 (MEN-1)
• Neurofibromatosis

If excess growth hormone occurs after normal bone growth has stopped, the condition is known as acromegaly.

Gigantism is very rare.

The child will grow in height, as well as in the muscles and organs. This excessive growth makes the child extremely large for his or her age.

Other symptoms include:

• Delayed puberty
• Double vision or difficulty with side (peripheral) vision
• Frontal bossing and a prominent jaw
• Headache
• Increased sweating
• Irregular periods (menstruation)
• Large hands and feet with thick fingers and toes
• Release of breast milk
• Thickening of the facial features
• Weakness

• CT or MRI scan of the head showing pituitary tumor
• Failure to suppress serum growth hormone (GH) levels after an oral glucose challenge (maximum 75g)
• High prolactin levels
• Increased insulin growth factor-I (IGF-I) levels

Damage to the pituitary may lead to low levels of other hormones, including:

• Cortisol
• Estradiol (girls)
• Testosterone (boys)
• Thyroid hormone

Pituitary surgery is usually successful in limiting growth hormone production.

• Delayed puberty

Surgery and radiation can both lead to low levels of other pituitary hormones, which can cause:

• Adrenal insufficiency
• Diabetes insipidus (rarely)
• Hypogonadism
• Hypothyroidism

Call your health care provider if your child has signs of excessive growth.

Melmed S, Kleinberg D. Anterior pituitary. In: Kronenberg HM, Melmed S, Polonsky KS, Larsen PR. Williams Textbook of Endocrinology. 11th ed. Philadelphia, PA: Saunders Elsevier; 2008:chap 8.