Gigantism is abnormal growth due to an excess of growth hormone during childhood.
Gigantism; Pituitary giant; Overproduction of growth hormone; Growth hormone - excess production
The most common cause of too much growth hormone release is a noncancerous (benign) tumor of the pituitary gland. Other causes include:
- Genetic disease that affects the skin color (pigmentation) and causes benign tumors of the skin, heart, and endocrine (hormone) system (Carney complex)
- Genetic disease that affects the bones and skin pigmentation (McCune-Albright syndrome)
- Genetic disease in which one or more of the endocrine glands are overactive or form a tumor (Multiple endocrine neoplasia type 1)
- Disease in which tumors form on the nerves of the brain and spine (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
- Very prominent forehead (frontal bossing) and a prominent jaw
- Gaps between the teeth
- Increased sweating
- Irregular periods (menstruation)
- Large hands and feet with thick fingers and toes
- Release of breast milk
- Sleep problems
- Thickening of the facial features
- Voice changes
Exams and Tests
The doctor will perform a physical exam and ask about the child's symptoms.
Laboratory tests that may be ordered include:
- Estradiol (girls)
- Growth hormone suppression test
- Insulin-like growth factor-I
- Testosterone (boys)
- Thyroid hormone
For pituitary tumors that have clear outlines, surgery can cure many cases.
When surgery cannot completely remove the tumor, medicines are used to block or reduce growth hormone release or prevent growth hormone from reaching target tissues.
Sometimes radiation treatment is used to decrease the size of the tumor after surgery.
Pituitary surgery is usually successful in limiting growth hormone production.
Early treatment can reverse many of the changes caused by growth hormone excess.
Surgery may lead to low levels of other pituitary hormones, which can cause any of the following conditions:
- Adrenal insufficiency (adrenal glands do not produce enough of their hormones)
- Diabetes insipidus (extreme thirst and excessive urination; in rare cases)
- Hypogonadism (body's sex glands produce little or no hormones)
- Hypothyroidism (thyroid gland does not make enough thyroid hormone)
When to Contact a Medical Professional
Call your health care provider if your child has signs of excessive growth.
Katznelson L, Laws ER Jr, Melmed S, et al. Acromegaly: an Endocrine Society clinical practice guideline. J Clin Endocrinol Metab. 2014;99:3933-51. PMID: 25356808 www.ncbi.nlm.nih.gov/pubmed/25356808.
Melmed S. Acromegaly. In: Jameson JL, De Groot LJ, de Kretser DM, et al, eds. Endocrinology: Adult and Pediatric. 7th ed. Philadelphia, PA: Elsevier Saunders; 2016:chap 12.
Reviewed By: Brent Wisse, MD, Associate Professor of Medicine, Division of Metabolism, Endocrinology & Nutrition, University of Washington School of Medicine, Seattle, WA. Also reviewed by David Zieve, MD, MHA, Isla Ogilvie, PhD, and the A.D.A.M. Editorial team.