Growth Hormone Deficiency
Article updated and reviewed by Hubert Chen, MD, Associate Director of Medical Sciences, Amgen Inc. and Assistant Professor of Clinical Medicine University of California, San Francisco on April 18, 2005.
Growth hormone is secreted by the pituitary gland in the brain and plays an important role in the regulation of growth in children and overall metabolism in adults. The effects of GH are mediated almost exclusively by another molecule called IGF-1 (insulin-like growth factor 1), which is produced primarily in the liver. Growth hormone (GH) deficiency refers to inadequate levels of GH (and therefore IGF-1), resulting in growth retardation in children and metabolic disturbances in adults.
GH deficiency can occur as an isolated deficiency or in combination with other pituitary hormones. In the latter case, the condition is termed hypopituitarism, and one or more of the following hormones may be deficient: corticotropin (ACTH), thyroid-stimulating hormone (TSH), luteinizing hormone (LH), follicle-stimulating hormone (FSH), growth hormone (GH), or prolactin. When GH deficiency is diagnosed, it is critical to make sure that the other pituitary hormones are functioning properly.
GH deficiency, whether alone or in association with other abnormalities, is hereditary in about 10 percent of all cases.
Congenital hypopituitarism, a rare form of GH deficiency, may be genetic and frequently is fatal if not diagnosed in the neonatal period.
Secondary GH deficiency can occur due to central nervous system tumors, trauma, surgery involving the hypothalamus or
pituitary gland in the brain, or radiation.
Idiopathic GH deficiency (of unknown cause) accounts for most cases.
In children, symptoms of GH deficiency may not be apparent at birth, but by age 6 months, growth retardation is obvious. In children, inspection may reveal short stature, delayed secondary tooth eruption, and delayed puberty.
Those with isolated GH deficiency may have normal body proportions. Determination of bone age from hand X-rays is important in evaluating growth problems, as is the careful recording of height and weight over time on any of several available growth charts.
GH deficiency in adults causes an increase in fat tissues and a decrease in muscle mass. In addition, GH deficiency may negatively affect functioning of the heart (decreased cardiac output) or skeletal muscle (physical weakness). However, common (and perhaps major) complaints in adults may be lethargy and decreased sense of well-being that are frequently attributed to “old age”.
Blood tests are typically required to make the diagnosis of GH deficiency. “Provocative tests” may be done to determine whether the secretion of growth hormone is adequate after appropriate stimulation (e.g., exercise, insulin administration and clonidine). In other words, the tests will determine whether there is a normal and appropriate surge in the blood level of GH after the pituitary gland is provoked. Measurement of IGF-1 levels may sometimes be used as a screening test.
Radiographic studies may be required. Evaluation of the sella tursica (a saddle like prominence on the upper surface of the sphenoid bone in the brain) with MRI (Magnetic Resonance Imaging) is performed to rule out calcification and tumors. The sella is abnormally small in 10 to 20 percent of children with pituitary GH deficiency.
As previously stated, evaluation of other pituitary hormones or glands may be required to make sure that the GH deficiency is not accompanied by other endocrine disorders.
Replacement therapy with hGH (human Growth Hormone, somatropin) ) is indicated for all children who have documented GH deficiency and have short stature. Patients with hypopituitarism may also need adrenal and thyroid hormone replacement and, as they approach puberty, sex hormones.
Although the benefits of treating GH deficiency in children are well recognized, there is still significant debate about the value of treating GH deficiency in adults. There is concern that the magnitude of improvement in body composition and functional capacity may not be worth the financial cost or side effects of somatropin treatment. Hand swelling and stiffness, joint and muscle ache, and insulin resistance are the most common side effects. In addition, there are reports linking increased cancer risks with increased GH activity/IGF-1 levels in population studies. Although a causal relationship remains to be proven, these reports suggest that the risk-to-benefit ratio of treating GH deficiency in adults needs to be more precisely determined. As a result, most physicians are conservative in initiating somatropin therapy in adults.
Are there any tests that need to be performed to rule out any other disease?
What is the cause of the GH deficiency?
Will you be prescribing growth hormone replacement therapy?
What are the side effects?
Will the child have to remain on this medication for the rest of his/her life?
How much can we expect the child to grow while on the hormonal therapy?
Has there been any permanent damage done already?
Editorial review provided by VeriMed Healthcare Network.