Growth Hormone Deficiency

Introduction

Is your child much shorter than his or her friends and schoolmates? Does your child's stature influence his or her mood, lifestyle, or popularity? Short stature affects about 1.8 million children in the United States. One of the least common causes of short stature is growth hormone deficiency (GHD). But when GHD is diagnosed, treatment is usually quite successful. Read on to learn about GHD, what causes it, and the available treatments.

What is it?

Individuals with GHD do not produce enough growth hormone, or somatotropin. Their growth typically begins to slow between the ages of 6 months and 3 years. By their third birthday they may be considerably shorter than their peers. Children with GHD also may have an immature facial appearance, and they may weigh more than other children of similar stature who don't have the condition.

Adults may have GHD, but their symptoms often do not include abnormal height. Their symptoms typically are more general than those experienced by children and may include fatigue, muscle weakness, an overall feeling being stressed, and other emotional problems.

Growth hormone is released from the pituitary gland and is required for appropriate growth. Growth hormone also plays an important role in the breakdown of carbohydrates and fats in the body. The pituitary gland is located in the middle of the skull, under the hypothalamus, at the base of the brain. Its two regions are called the anterior lobe, located in the front of the gland, and the posterior lobe, in the back. The pituitary gland is often called the master gland because it is responsible for the release of many important bodily hormones, including growth hormone, which is released from the anterior lobe. The hypothalamus controls the release of hormones from the pituitary gland's two lobes.

Growth hormone-releasing hormone signals the pituitary gland to release growth hormone. The release of growth hormone also is dependent on the presence of other substances such as adrenocorticotropic hormone; vasopressin (or anti-diuretic hormone); somatostatin (a hormone released by the hypothalamus); and growth hormone-releasing peptide; as well as on the individual's food intake, sleep pattern, exercise regimen, physical and mental stress, and medication use. Other factors that may affect the release of growth hormone by the pituitary gland, leading to growth hormone deficiency, include increased blood sugar after meals, elevated free-fatty acids, elevated insulin-like growth factor-I, progesterone, and many prescription drugs.

What causes it?

Growth hormone deficiency can be a congenital condition (the individual is born with the disorder) or an acquired condition (the individual develops the condition later in life). The condition is considered partial if some growth hormone is produced (but not enough for normal development) or absolute if no hormone is produced.

Individuals with congenital GHD usually have the absolute version of the condition. The cause of congenital GHD is thought to be a genetic abnormality. Acquired GHD, by contrast, is usually partial in nature and can result from any of the following:

  • A tumor in the hypothalamus or pituitary gland
  • Damage to the hypothalamus or pituitary gland from radiation treatment to the head or neck area
  • Brain damage from head trauma
  • An infection of the central nervous system (for example, meningitis)
  • An underactive thyroid gland, which controls the functioning of the hypothalamus and pituitary gland
  • Poorly controlled diabetes
  • Use of prescription drugs such as corticosteroids (for example, prednisone), methylphenidate (Ritalin), and dextroamphetamine (Adderall), which can decrease or inhibit the release of growth hormone

Who has it?

Both children and adults can suffer from GHD. Children with GHD are generally born with the disorder. Some adults with GHD had the disorder as children and continue to experience symptoms. Other adults develop GHD during adolescence or adulthood, possibly as a result of a disease such as cancer or an infection (for example, meningitis) that causes the pituitary gland or hypothalamus to malfunction. The occurrence of GHD is more common in males than females.

What are the risk factors?

The most common risk factors associated with the development of GHD are the following:

  • Family history of GHD
  • Radiation therapy of the head or neck region
  • Diabetes mellitus
  • Hypothyroidism (low levels of thyroid hormone)
  • Tumor of the hypothalamus or pituitary gland
  • Head trauma
  • Infection such as encephalitis (inflammation of the brain) or meningitis (infection caused by a virus or a bacteria that results in inflammation of brain or spinal cord tissues)
  • Use of prescription drugs such as corticosteroids (like prednisone), methylphenidate (Ritalin), dextroamphetamine (Adderall)

What are the symptoms?

The following are the most common characteristics of GHD in children:

  • Noticeably shorter height compared to peers
  • Grows less than 2 inches per year
  • Full, round, immature-looking face
  • Chubby or obese abdomen
  • Slow sexual maturation

Adults with GHD may be of normal height but often suffer from the following symptoms:

  • Lack of energy
  • Muscle weakness
  • Finely wrinkled, thinning skin
  • Bone loss; weak, brittle bones
  • Fat around the face and abdomen
  • Emotional symptoms such as depression
  • High cholesterol, including LDL ("bad") cholesterol
  • Increased insulin production
  • Decreased exercise tolerance
  • Impaired temperature control; decreased sweating
  • Loss or decrease of libido
  • Sleep disturbances

How is it treated?

The primary goal of treatment of GHD in children is to restore growth hormone to typical levels so the child can grow to a normal height. Goals for adults are to relieve symptoms such as fatigue and muscle weakness, and to reverse any metabolic abnormalities associated with the condition, such as increased insulin production and erratic body temperature.

The mainstay of treatment for both children and adults is growth hormone replacement therapy. Growth hormone must be supplemented or replaced by using synthetic (artificially made) growth hormone, which is made through recombinant DNA technology. Somatrem (Protopin) and somatropin (Genotropin, Norditropin, Nutropin) are recombinant growth hormone products that are the drugs of choice for treating GHD. A newer drug, sermorelin (Geref), is frequently used in children as well. It is a synthetic growth hormone-releasing hormone product, also made through recombinant DNA technology that works by stimulating the pituitary gland to release growth hormone. Sermorelin therefore is not beneficial for children with congenital GHD, who do not have functioning pituitary glands.

Natural growth hormone derived from human pituitary glands was at one time used for the treatment of GHD. However, severe and sometimes fatal adverse reactions were associated with this drug, so the Food and Drug Administration (FDA) required its removal from the U.S. market.

Children with GHD are typically treated with supplemental synthetic growth hormone for a number of years until they either have reached an acceptable height for their age or have reached their maximum growth potential. Parents of children with GHD who are undergoing treatment should be patient. A noticeable increase in growth may take 3 to 4 months of treatment. Along with affecting height by promoting bone growth, growth hormone treatment affects muscles as well. Children and their parents also should see weight loss with treatment as a result of decreasing body fat and a trimmer overall look.

Adults with GHD, by contrast, are usually treated with synthetic growth hormone to ease the symptoms associated with the deficiency rather than to increase height. A decrease in body fat and an increase in lean muscle tissue, improved mood, and improved exercise performance are commonly achieved through treatment. Treatment in adults may also have the beneficial effects of lowering cholesterol levels and increasing bone density, decreasing the risks for high cholesterol and osteoporosis.

To learn more about the drugs used as growth hormone replacement therapy, click on the Drug Class links below.

Helping Yourself

It is important for children and adults with GHD to practice good health behaviors and take good care of themselves. Some recommendations are as follows:

  • Eat a balanced diet (a healthy diet will also promote growth)
  • Get plenty of rest
  • Seek emotional support (ask your doctor for information about support groups in your community)
  • Follow your doctor's directions and advice
  • Inform all healthcare providers that you use growth hormone replacement therapy
  • Take growth hormone replacement therapy exactly as directed
  • Get regular exercise under a doctor's supervision

What is on the horizon?

Some biosynthetic growth hormone products are currently being investigated, including examorelin (Hexarelin). Like growth hormone-releasing hormone products, these drugs are growth hormone-releasing peptides that stimulate the release of growth hormone, but they work at different sites in the body. These products may provide added benefit when used in combination with growth hormone-releasing hormone products. Also encouraging is that they have been shown to be effective when given orally or nasally, or when injected.

Research is ongoing to better understand the causes of GHD and discover ways to prevent the disorder. Current technological advances offer strong hope that medicines to prevent and even cure growth hormone deficiency will be developed.

References

American Association of Clinical Endocrinologists website. Available at: http://www.aace.com. Accessed June 2005, June 2006, and April 2007.

Growth Hormone Deficiency. Human Growth Foundation website. Available at: http://www.hgfound.org/growth.html. Accessed June 2005, June 2006, and April 2007.

Heck AM, Yanovski JA, Calis KA. Pituitary gland disorders. In: DiPiro JT, Talbert RL, Yee GC, et al. (eds.). Pharmacotherapy: A Pathophysiologic Approach. 6th ed. New York: McGraw-Hill. 2005; 1407-1423.

Hormone Foundation website. Available at: http://www.hormone.org. Accessed June 2005, June 2006, and April 2007.

The Magic Foundation website. Available at: http://www.magicfoundation.org. Accessed June 2005, June 2006, and April 2007.

Growth Hormone Deficiency Health Condition Last Updated: April 2007

Note: The above information is intended to supplement, not substitute for, the expertise and judgment of your physician, pharmacist, or other healthcare professional. It is not intended to diagnose a health condition, but it can be used as a guide to help you decide if you should seek professional treatment or to help you learn more about your condition once it has been diagnosed.

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