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Adult Growth Hormone Deficiency
Growth hormone (often referred to as hGH, or simply GH) doesn't just contribute to physical growth in children. Adults need growth hormone, too. In adults, it is essential to maintain healthy body composition and metabolism. When an adult's body is unable to produce enough growth hormone, he or she is said to have adult growth hormone deficiency (AGHD).

The healthy body continues to produce growth hormone even after growth has stopped. Medical research indicates that adults need adequate levels of this hormone to maintain healthy body composition and metabolism. Growth hormone plays an important role in maintaining a normal ratio of body fat to lean mass, "bad" to "good" cholesterol levels, and proper bone mineral density.

AGHD occurs when the pituitary gland (a gland about the size of a pea, located at the base of the brain) does not secrete enough growth hormone. The pituitary gland is often called the "master gland" because it controls many different kinds of hormones. If the pituitary gland is missing or does not function correctly, it may be necessary to replace some or all of the hormones that the gland cannot provide; one of which is growth hormone. In adult patients, pituitary disease occurs as a result of pituitary tumors, pituitary surgery, radiation therapy, or head injury.

Growth hormone therapy is indicated to treat adult growth hormone deficiency and should not be used for "anti-aging" purposes or athletic enhancement.

The two types of AGHD and what you can do about them
Generally, adults with growth hormone deficiency can be divided into two groups: those who were GH-deficient as children and continue to be so as adults (childhood-onset patients), and adults with pituitary disease who became GH-deficient as adults (adult-onset patients).

Signs and symptoms of both childhood-onset and adult-onset AGHD may include:

  • Increased body fat, especially around the abdomen
  • Decreased muscle mass
  • Lower bone mineral density
  • Predisposition to atherosclerosis (hardening of the arteries)

More about childhood-onset AGHD
In many people, adult growth hormone deficiency is the continuation of a disorder that began in infancy or childhood. This type of AGHD is referred to as childhood onset AGHD.

In some cases, the causes of GH deficiency in childhood cannot be determined; this type of disorder is referred to as idiopathic. Known causes may include:

  • Developmental defects in or near the pituitary gland
  • Genetic problems with the production of GH
  • Damage to the pituitary gland or the surrounding area due to tumors, infection, radiation treatment, or severe head injury

Some children with GH deficiency may gain the ability to secrete GH with time and may not require GH therapy as adults. However, scientific evidence suggests that many adults who were GH-deficient as children and continue to be GH-deficient as adults may need to continue therapy into adulthood in order to have enough GH to meet metabolic demands as adults (although many factors can contribute to such conditions).

Signs and symptoms of childhood-onset AGHD may include:

  • Increased body fat, especially around the abdomen
  • Decreased muscle mass
  • Lower bone mineral density
  • Predisposition to atherosclerosis (hardening of the arteries)

References
Lifshitz F, ed. Pediatric Endocrinology. 4th ed. New York, NY: Marcel Dekker Inc; 2003.
More about adult-onset AGHD
Some people with adult growth hormone deficiency were not GH-deficient as children. These people are said to have adult-onset AGHD.

The usual cause of adult-onset AGHD is damage to the pituitary gland, which is responsible for secreting GH. This damage is most commonly caused by one or more tumors in and around the pituitary. Such a tumor may compress the gland, or the damage may occur when the tumor is removed through neurosurgery. The pituitary gland may also be damaged by infection, blood vessel disease, severe head injury, or radiation treatment for tumors of the head or neck. Injury to the pituitary gland may affect the production of one or more pituitary hormones, including GH.

Signs and symptoms of adult growth hormone deficiency associated with pituitary disease may include:

  • Increased body fat, especially around the abdomen
  • Decreased muscle mass
  • Lower bone mineral density
  • Increases in LDL ("bad") cholesterol and decreases in HDL ("good") cholesterol
  • Decreased insulin sensitivity
  • Increased hardening of the arteries (atherosclerosis)
Reference
Wilson JD, Foster DW, Kronenberg HM, Larsen PR, eds. Williams Textbook of Endocrinology. 9th ed. Philadelphia, Pa: WB Saunders; 1998.
How does the healthcare provider determine if you have AGHD?
The signs and symptoms of adult growth hormone deficiency can be varied. People with this disorder often suffer from decreased energy levels and exercise capacity, as well as impaired psychological wellbeing. They may also experience metabolic changes which manifest as increased body fat, especially around the waist, and decreased muscle mass.

In addition, an adult who has experienced one or more of the following may be more likely to be evaluated for growth hormone deficiency:

  • Evidence of hypothalamic-pituitary disease
  • Cranial irradiation (radiation therapy for treatment of head and neck tumors)
  • Previous diagnosis of childhood-onset growth hormone deficiency
  • Multiple hormone deficiencies as a result of surgery or trauma

Your healthcare provider will perform diagnostic tests if he or she feels you may be at risk for growth hormone deficiency.

Criteria for a diagnosis of AGHD
In order to be diagnosed with adult growth hormone deficiency, you must meet either of the following two criteria:

First, you must be biochemically diagnosed with AGHD based on a smaller-than-normal response to a growth hormone stimulation test. This is a special blood test your healthcare provider may order if he or she suspects you are growth hormone deficient.

The second criterion is whether your growth hormone deficiency began in childhood or in adulthood. If you have adult-onset growth hormone deficiency, you must have a deficiency of growth hormone either alone, or in combination with deficiencies in other hormones, resulting from disease, surgery, radiation therapy, or trauma. If your growth hormone deficiency began in childhood, the diagnosis of your childhood condition will need to be confirmed prior to beginning therapy as an adult.

Keeping track of your own progress
If you are diagnosed with AGHD and begin Primatropin therapy, it's important to remember that evaluating the effectiveness of your therapy is the job of your healthcare provider.

References
Growth hormone deficiency in adults: diagnosis and treatment. Genentech, Inc.
Lifshitz F, ed. Pediatric Endocrinology. 4th ed. New York, NY: Marcel Dekker Inc; 2003.


Frequently Asked Questions
As an adult, the idea of taking "growth" hormone seems unusual. After all, most people reach full height during their teens. So, as an adult facing Primatropin therapy, it's only natural that you have some questions. While you should always make it a point to discuss any concerns with your healthcare provider, here are answers to some of the basic questions about adult growth hormone deficiency.

What is growth hormone?
Growth hormone (often referred to as hGH, or simply GH) is a protein that, among other things, tells a child's body to grow. It is produced by the pituitary gland (an organ about the size of a pea, located at the base of the brain) and released into the bloodstream.

What does growth hormone do?
As its name suggests, growth hormone is the chief hormone responsible for growth. In children, it stimulates the development of muscles and bones, and also helps regulate metabolism.

In adults, growth hormone is essential to the maintenance of healthy body composition and metabolism. Throughout adulthood, growth hormone plays an important role in maintaining an improved ratio of body fat to lean mass, "bad" to "good" cholesterol levels, and proper bone mineral density.

What is AGHD?
AGHD occurs when the pituitary gland does not secrete enough growth hormone. In adult patients, pituitary disease may occur as a result of pituitary tumors, pituitary surgery, radiation therapy, or head injury—impacting the gland's ability to produce sufficient growth hormone.

Are there two types of AGHD? Generally, adults with growth hormone deficiency can be divided into 2 groups: those who were growth hormone deficient as children and continue to be so as adults (childhood-onset patients) and adults with pituitary disease who became growth hormone deficient as adults (adult-onset patients).

How is AGHD diagnosed?
Your healthcare provider will perform diagnostic tests if he or she feels you may be at risk for growth hormone deficiency. In order to be diagnosed with adult growth hormone deficiency you must meet either of the following two criteria:

First, you must be officially diagnosed with AGHD based on a smaller-than-normal response to a growth hormone stimulation test.

If you have adult-onset growth hormone deficiency, you must have a deficiency of growth hormone either alone, or in combination with deficiencies in other hormones resulting from disease, surgery, radiation therapy, or trauma.

If your growth hormone deficiency began in childhood, the diagnosis of your childhood condition will need to be confirmed prior to beginning therapy as an adult.

What pituitary problems cause adult-onset growth hormone deficiency?
In adults, growth hormone deficiency may often result when the pituitary gland becomes diseased or damaged. Particular tumors of the pituitary gland (pituitary adenomas), physical injury to the brain (hemorrhage, trauma, surgery), or radiation therapy can all injure the pituitary gland severely enough to cause growth hormone deficiency.

In the U.S. approximately 50,000 adults have growth hormone deficiency and 6,000 new cases of AGHD are diagnosed each year. Children who receive growth hormone therapy may need to continue with the therapy into adulthood if AGHD is confirmed.

When can I expect to see results from my Primatropin therapy?
It may be a number of months until you see the results of your Primatropin therapy. The changes may be so gradual at first that they are difficult to notice, but try not to get discouraged. Take your replacement therapy when and how your healthcare provider instructs. If you take it every day and don't miss doses, you can improve the likelihood of positive results.

I am taking other hormone medicines—why do I need to take Primatropin therapy?
Depending on the cause of AGHD, many patients need to take other hormones. GH is produced by the pituitary gland—a small gland located at the base of the brain. This small gland is actually responsible for releasing and controlling many hormones in our bodies. Each of these hormones is released in tiny amounts into the blood stream. Once in the blood, each hormone travels to a different part of the body to perform a specific function. GH released from the pituitary is important for growth, body composition, lipid metabolism, and strength. Each of the other hormones released from the pituitary are important for other reasons—from salt and water regulation to helping our bodies deal with stress. Primatropin cannot replace the function of these other hormones. Remember to tell your healthcare provider about all of the medications that you take, including nonprescription medications and vitamins. >Why did my healthcare provider order a DEXA scan before I started taking Primatropin therapy? Dual-energy x-ray absorptiometry (DEXA) is a special kind of x-ray that uses a very low amount of radiation. It is the method that healthcare providers use to determine body composition or the proportion of your body that is made up of fat. DEXA is also considered the "gold standard" for measuring bone density. Patients with AGHD may experience changes in decreased bone density and body composition. By taking a DEXA scan before you begin treatment, your healthcare provider will have a baseline measurement of your bone density and the composition of your body.

How is the effectiveness of Primatropin therapy measured?
For adults on Primatropin therapy, success may be gauged using measures such as assessments of body fat and muscle mass, spine bone mineral density (in certain patients), and ratio of LDL to HDL cholesterol.

 

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