Growth Disorders Overview

 
 

One of the remarkable roles of the endocrine system is the regulation of growth and development throughout our bodies. This work is directed by the pituitary gland — perhaps the most important “master gland” of the endocrine system. A small oval-shaped organ at the base of the brain, the pituitary gland releases many types of hormones into the blood stream. One of these is growth hormone (GH) called somatotropin. Once in the blood, GH travels to bone, muscle, and other tissues where it has many effects. The hypothalamus, a small structure located at the base of the brain just above the pituitary, controls the release of growth hormone by the pituitary gland. The principal stimulator of growth hormone secretion is called the growth hormone-releasing hormone.

In children, for example, GH stimulates linear growth, or height. It is also important for the development of muscle and bone, and the distribution of body fat throughout the body. In adults, GH affects energy, muscle strength, bone health, and psychological well being. Having either too much or too little GH can cause health problems.

In some cases, individuals may have too much GH, a condition called acromegaly in adults. Acromegaly is usually caused by a non-cancerous pituitary gland tumor of the pituitary gland. In the rare instances when it occurs, too much GH in children causes gigantism.

A more common growth disorder is growth hormone deficiency (GHD). This is the condition of having too little GH. There are several possible explanations for its occurrence:

  • A child can be born with GHD.
  • The condition also may arise because of damage to the hypothalamus or pituitary gland as a child or adult because of a tumor, an infection, or radiation to the brain — usually for the treatment of a tumor.
  • A deficiency in GH may also have an undefined cause. (In this case, it is said to be of idiopathic origin.)

Pituitary disorders, such as GH excess or GHD, are evaluated and treated by endocrinologists — medical specialists in hormone-related conditions. Because the diagnosis and treatment of such disorders require special expertise, primary care physicians who suspect patients have GH abnormalities should refer them to an endocrinologist.

 

Growth Hormone Excess

  
 

Excess growth hormone (GH) in children (gigantism) is extremely rare, occurring in fewer than 100 children in the United States.

Excess GH in adults (acromegaly) most commonly occurs in middle-aged men and women. Approximately 60 out of every million Americans have acromegaly.

Very infrequently, GH excess may run in families, or be one manifestation of a number of rare syndromes.

  

 

 

Incidence and Prevalence

  
 

Estimates for the number of growth hormone deficiency (GHD) cases vary. Some countries have reported one in 10,000 children with GHD while others have reported one in 3,500 children.

Some children are born with GHD, which is called congenital GHD. In others, GHD develops at some point during childhood or adolescence, which is termed acquired GHD. Sometimes the cause of the GHD is relatively obvious, such as in a child born with structural brain abnormalities, or a history of head trauma. However, in other cases the cause of the GHD is unknown, or idiopathic.

For adult-onset GHD, indirect estimates based on the incidence of pituitary gland tumors suggest an incidence of 10 cases per million people annually. In the United States, the exact prevalence of GHD is unknown. About 35,000 adults have GHD, with about 6,000 newly diagnosed each year.

  

 

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