Because adults are no longer growing, growth hormone deficiency (GHD) in adults manifests itself less as a growth disorder and more as an imbalance of the hormones that keep our bodies functioning. The amount of growth hormone, or somatotropin, that our bodies produce declines with age, but a true deficiency is almost always caused by damage to the pituitary gland.

The signs of insufficient growth hormone include muscle weakness, tiredness, and a tendency to get out of breath more easily due to weaker heart muscle and cardiac output. You may also feel a lack of energy as your body's metabolic rate slows. Weight gain is common as body fat increases and muscle mass decreases. Blood tests may show elevated fats in the blood, higher cholesterol, and higher triglycerides. Blood pressure may rise as well. Some people have trouble sleeping or notice that their concentration and memory are poorer. Some studies have even linked growth hormone deficiency to premature cardiovascular disease, according to the American Association of Clinical Endocrinologists.

Because growth hormone is an important part of your overall hormonal system, a deficiency can have psychological symptoms as well. People with GHD often find themselves feeling shy or withdrawn. Some feel anxious, while others find themselves unusually sad or depressed.

Growth hormone levels are hard to measure accurately since the hormone is released in pulses primarily at night and remains in the blood a very short time -- only 19 minutes. Therefore a single reading is rarely accurate. The most accurate test is called a growth hormone stimulation test and measures the amount of GH produced in response to a stimulus. Currently the insulin tolerance test, which measures the body's response to insulin-induced hypoglycemia, is considered the best predictor of GHD. However, your doctor can't use this test if you have a history of coronary artery disease. Another accurate stimulation test measures the response to arginine and growth hormone releasing hormone.

If you have another hormone deficiency, such as a thyroid disorder, your doctor will probably want to make sure you are on adequate hormone replacement for that condition prior to stimulation testing. The night before the test you won't be able to eat or drink after midnight and you shouldn't exercise the morning of the test. If the tests reveal that your peak growth hormone level is less than 3 to 5 mcg/L, then you are probably deficient. But keep in mind that your doctor will take other things into consideration, such as whether you were growth hormone deficient as a child or your pituitary gland was damaged in some way, before making a final diagnosis.

In fact, Growth Hormone Deficiency (GHD) is not very common: in the United States approximately 50,000 adults have GHD and 6,000 new cases are diagnosed each year, according to the American Association of Clinical Endocrinologists.

If your doctor is recommending human growth hormone, there are a number of factors you need to consider. Cancer is a primary concern, since some experts suspect that growth hormone could make tumors grow more quickly. Cancer patients should be in remission for five years before growth hormone treatment is recommended.

You should also be tested for diabetes, since 40 percent of adults on growth hormone develop diabetes or glucose intolerance, according to Dr. David Cook, an endocrinologist at Oregon Health and Science University. "Growth hormone can aggravate insulin effects, so if you're already diabetic it may get worse," says Cook.

Lastly, remember that once you start taking growth hormone you will likely be doing so for the rest of your life, since a growth hormone deficiency doesn't correct itself. Your doctor will need to monitor your hormone levels regularly. According to experts, growth hormone is likely to be safe as long as you are replenishing a deficiency and bringing the level in your body up to a normal level for someone your age. People who take growth hormone to fight aging, however, are venturing into unknown territory.

Common side effects of growth hormone treatment include edema, tingling in the hands and feet -- probably as a result of swelling -- aching joints, and headaches. All of these are thought to be reversible by decreasing the dosage of growth hormone.

References

First published December 17, 2003
Last updated December 16, 2008
Copyright © 2003 Consumer Health Interactive

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