Growth Hormone Deficiency in Adults
In adults, deficiency of growth hormone can develop in the following situations:
1. A large pituitary tumor.
2. After surgery or radiation therapy of a pituitary tumor or other brain tumors.
3. Secondary to hypothalamic disorders.
4. Continuation of childhood growth hormone deficiency into adulthood.
Deficiency of growth hormone is very common in patients with large pituitary tumors, especially after surgery or radiation therapy of these tumors.
Deficiencies of other hormones such as thyroid hormone, cortisol and testosterone (or estrogen in women) also usually develops in these cases. Together, these deficiencies are known as Panhypopituitarism.
Until recently, panhypopituitarism has been treated with cortisone, thyroid hormone replacement and testosterone (or estrogen in women) only. Growth hormone deficiency has been ignored. However, in the past few years, several studies have clearly demonstrated the benefits of growth hormone therapy in these growth hormone deficient patients.
Clinical Features of Growth hormone deficiency
Reduced exercise capacity.
Increase in body fat and decrease in muscle mass.
Increase in LDL cholesterol (bad cholesterol) and triglycerides
and decrease in HDL cholesterol (good cholesterol).
Increased risk for heart attack, heart failure and stroke.
Decrease in bone mass with increased risk for fractures.
Anxiety and depression, especially lack of sense of well-being, social isolation and reduced energy.
Diagnosis of Growth hormone Deficiency
Random growth hormone level determination should not be used as a diagnostic test for growth hormone deficiency, because growth hormone is secreted in pulses and in normal individuals, blood growth hormone levels are undetectable at least 50% of the day.
Diagnosis of growth hormone deficiency requires special endocrine testing, called growth hormone stimulation testing.
These tests include: Insulin hypoglycemia test, L-Dopa stimulation test, Arginine infusion test, Arginine/GHRH test.
At least one of these tests should be positive before a person is diagnosed as growth hormone deficient.
These tests should be carried out in consultation with an endocrinologist.
Treatment of Growth hormone deficiency
Growth hormone deficiency is treated with recombinant human growth hormone which is given with a subcutaneous injection on a daily basis.
The generic name for growth hormone is Somatropin.
Brand names include Genotropin, Nutropin, Nutropin AQ and Humatrope.
Growth hormone replacement therapy should be carried out in consultation with an endocrinologist, who will monitor the dose of growth hormone closely, as most side-effects of growth hormone replacement therapy are dose-related.
Benefits of Growth hormone therapy
Growth hormone therapy in growth hormone deficient adult patients have been shown to have the following beneficial effects:
1. Improved sense of well being.
2. Decrease in cholesterol level.
3. Increase in muscle mass and decrease in fat mass with no change in total body weight.
4. Increase in muscle strength.
5. Increase in bone mass.
6. Improvement in heart function.
7. Increased exercise capacity.
Side-effects of Growth hormone therapy
Some of the side-effects of Growth hormone therapy include:
1. Edema (swelling).
2. Joint pains.
3. Muscle pains.
4. Tingling, numbness, usually at the wrist.
5. Carpal tunnel syndrome.
These side-effects are usually due to a large initiating dose of growth hormone and usually subsides by reducing the dose.
There has been some concern about the possibility of "cancer growth promotion" with growth hormone therapy, based upon a report of a few cases of Leukemia reported in children treated with growth hormone therapy.
This article was written by Sarfraz Zaidi, MD, FACE. Dr. Zaidi specializes in Diabetes, Endocrinology and Metabolism.
Dr. Zaidi is a former assistant Clinical Professor of Medicine at UCLA and Director of the Jamila Diabetes and Endocrine Medical Center in Thousand Oaks, California.
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