 We often think of Growth Hormone Deficiency as a childhood issue. This is true. However, it can be a deficiency which follows an affected person into adulthood. The transition from childhood growth hormone deficiency to adult growth hormone therapy (which will last a lifetime) can be confusing. Dr. Underwood prepared the following article to assist our understanding of this transition from childhood growth hormone deficiency to adult growth hormone therapy. Please feel free to call us with any questions you may have, or for additional assistance.
Growth Hormone Therapy- The Transition to Adulthood
Growth hormone (GH; somatotropin), a principal stimulator of body growth, is produced by the pituitary (or master) gland, a small structure located at the base of the brain. Production of too little Growth Hormone (growth hormone deficiency; GHD) in children causes growth to be slow. Because Growth Hormone Deficiency produces striking effects in children and has been a recognized condition for many years, we usually associate the term GHD with children and with the process of statural growth. Growth Hormone, however, is also secreted in adult life, and adults need Growth Hormone to maintain health. Adults who produce too little Growth Hormone also are designated as Growth Hormone Deficient, or we sometimes use the term somatotropin deficiency.
Causes of Growth Hormone Deficiency
Growth Hormone Deficiency in many adults is the continuation of a process that began in infancy or childhood, or it may have its onset after adulthood is reached. The most common form of Growth Hormone Deficiency beginning early in life is termed "idiopathic", meaning that the cause is not determined. Known causes beginning in childhood include developmental defects in the region of the pituitary gland, genetic problems with the production of GH, damage to the pituitary area resulting from tumor, infection, irradiation, etc. The most common causes of adult-onset Growth Hormone Deficiency are tumors in and around the pituitary gland. Such tumors may compress and damage the remaining pituitary gland, or the GHD may follow efforts to remove the tumor. Other causes of damage to the pituitary of adults include infection, blood vessel disease, and irradiation administered for treatment of tumors of the head or neck.
The Adult Who Was Growth Hormone Deficient During Childhood
In the 3½ decades that Growth Hormone has been used therapeutically, the emphasis has been on alleviation of the short stature of Growth Hormone deficient children. For the most part, these patients have been led to believe that the only purpose of GH therapy was to stimulate their growth so that they would achieve an acceptable adult height and that therapy would not be needed once they reached their adult height. Experience in recent years, however, has led to the conclusion that many, if not most, of the adults who were GH deficient during childhood need to continue GH therapy in adult life.
Several findings have led to this conclusion:
When GH therapy is stopped, the young Growth Hormone deficient adult tends to gain weight and become relatively obese. This excess of body fat tends to accumulate around the abdomen.
The cessation of Growth Hormone therapy results in a loss of lean body tissue. This is manifest principally by a decrease in muscle mass.
This relative deficiency of muscle mass results in diminished strength and physical performance, changes that may be manifest as decreased ability to perform tasks such as lifting heavy loads or to sustain physical tasks for long periods of time. Adults with Growth Hormone Deficiency have impaired ability to consume oxygen and expend their body energy, both at rest and at work.
 Adults with Growth Hormone Deficiency also may have lower mineral content in their bones, predisposing them to fractures. All of us lose bone mineral and have increased tendency to fracture our bones as we age. This natural process may be accelerated by deficiency of GH. Additionally, if the Growth Hormone Deficient adult had insufficient GH during childhood, when bones normally accumulate mineral, he/she is likely to begin adult life with low bone mineral content. This, superimposed on the loss of mineral during adulthood, eventually results in lower-than-normal bone mineral content and a greater predisposition to fractures.Blood lipid profiles in adults with GHD are such that they are likely to be predisposed to atherosclerosis. Their blood levels of total cholesterol., low-density lipoprotein cholesterol, and triglycerides are higher than individuals who have normal GH secretion. Suggesting that these findings are significant is the observation that adults with hypopituitarism (GH deficiency associated with deficiencies of other pituitary hormones) have an increased mortality rate. Despite replacement of the thyroid, adrenal and gonadal hormones, their excess death rate is due mainly to vascular problems of the type commonly resulting from athrogenic lipid profiles.
Treatment of the Growth Hormone Deficient Adult Who Had Growth Hormone Deficiency in Childhood
Young adults who were GHD during childhood may have signs and symptoms of impaired psychological well-being. These include feelings of depressed mood, emotional instability, social isolation, anxiety and reduced vitality. Although most children who have GH deficiency will be GH deficient in adulthood, the capacity of some patients to secrete GH improves over time. Some patients, therefore, will not need GH therapy in adult life. This is why it is important that as each GH deficient child reaches adulthood, studies be done to determine need for continuing therapy. The extent and nature of testing needed for this purpose will vary from one patient to another.
If treatment is needed, a variety of beneficial effects can be anticipated:
Effects on Body Composition
GH therapy for as little as six months causes as much as a 25% reduction in body fat, with the greatest reduction occurring in the region of the abdomen. Concurrently, the reduced lean tissue mass of the GHD patient is increased substantially by treatment with GH. This change is reflected in large part by improvement in muscle mass. Although improvements in bone mineral density would be an anticipated effect of GH replacement therapy, systematic studies have not shown that this occurs. However, long periods of observation are needed to assess changes in bone mineral density.
Effects on Physical Performance
Probably because of its beneficial effects on skeletal muscle, heart muscle and metabolism, treatment with GH improves exercise performance, oxygen consumption and cardiac output.
Effects on Blood Lipid Levels
The blood lipid profile improves with GH therapy. Specifically, total cholesterol and low density and lipoprotein cholesterol are reduced and high-density lipoprotein cholesterol (good cholesterol) is increased. The extent to which these changes retard the development of atherosclerosis are not yet known.
Effects on Psychological Well Being
One of the striking effects of GH therapy in GHD adults is the improve-ment in psychological well-being reported by these patients. Many experience a rapid improvement in their energy level. Improvements in mood and in the level of perceived psychological distress also have been documented.
Other Considerations
Treatment with GH requires that the hormone be injected daily into the fat tissue beneath the skin. This is made relatively simple by the need for small volumes of GH and the availability of fine, small-bore needles.
In the hierarchy of treatments used for patients with various illnesses, GH is relatively safe. Over 30 years of experience with GH therapy in children has uncovered few adverse effects of the hormone. In adults, who are treated with a smaller weight-related dose, edema (collection of fluid in tissue) and discomfort in the joints are sometime reported. Decreasing the dosage temporarily can relieve these. Because GH antagonizes the action of insulin, it will tend to raise blood sugar values, although this has not proven to be a significant problem in children. Individuals with prolonged excessive GH from a pituitary tumor have a tendency to develop tumors elsewhere in the body. This raises the concern that GH might promote the development or growth of tumors. This, however, has not been observed to be the case with GH therapy.
Adults produce and need GH.
Adults who are deficient in GH accumulate excess fat, have deficient lean tissue, have lower bone mineral content, have an unfavorable blood lipid profile, and experience undesirable psychological effects.
Treatment with GH reverses/attenuates many of the effects of GH deficiency-leading to better physical performance and a healthier psychological status.
Use of GH in children for nearly 40 years indicates that it has a high degree of safety.
The Transition from Child to Adult Growth Hormone Therapy
Contributed By:
Louis E. Underwood, M.D
Chapel Hill, NC
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ADDITIONAL Pages commonly requested by growth hormone deficient parents:
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Remember, MAGIC is made up of parents of affected children some of who are now affected adults. If you need to speak to someone about your child's transition to adult growth hormone therapy feel free to call us (9-4 Central time) or email us anytime!
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