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Growth Hormone Deficiency |
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Definition
Growth hormone deficiency entails inadequate levels of, or response to, growth hormone and its clinical manifestations.
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Description
A complex syndrome marked by metabolic dysfunction, sexual immaturity, and growth retardation (when it occurs in childhood). It can occur as an isolated deficiency or in combination with other pituitary hormone deficiencies.
Hypopituitarism results from a deficiency of the hormones secreted by the anterior pituitary gland, including growth hormone.
Panhypopitiutarism refers to a generalized condition caused by partial or complete failure of the pituitary gland to produce all six of the vital hormones: corticotropin (ACTH), thyroid-stimulating hormone (TSH), luteinizing hormone (LH), follicle-stimulating hormone (FSH), growth hormone (GH), and prolactin.
Although endocrine disorders constitute a minority of all causes of growth retardation, it is important to try to identify them because they are treatable.
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Causes and Risk Factors
Growth hormone 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 (unknown cause) GH deficiency accounts for most cases.
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Symptoms
Physical signs 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.
Evaluation of the sella turcica (a saddle like prominence on the upper surface of the sphenoid bone in the brain) with CT (Computed Tomography) or MRI (Magnetic Resonance Imaging) is indicated to rule out calcification and neoplasms. The sella is abnormally small in 10 to 20 percent of children with pituitary GH deficiency.
Growth deficiency in adulthood tends to cause mild to moderate obesity, weakness (asthenia), and reduced cardiac output.
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Diagnosis
In suspected hypopituitarism, evaluation must confirm hormonal deficiency caused by impairment or destruction of the anterior pituitary gland. Evaluation must also rule out disease of the target organs (adrenals, gonads, and thyroid gland) or the hypothalamus (plays a role in the nervous mechanisms underlying moods and motivational states).
Blood tests may be done to help make the diagnosis. "Provocative tests" may be done to determine if the secretion of growth hormone is adequate after appropriate stimulation (e.g., exercise, insulin administration, clonidine). In other words, the tests will determine if there is a normal and appropriate surge in the blood level of GH after the pituitary gland is provoked. Radiologic studies may also be required.
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Treatment
Replacement therapy with hGH (human Growth Hormone, somatropin) is indicated for all children with short stature who have documented with GH deficiency. Reported side effects of somatropin therapy include edema (swelling), hand stiffness, joint pain, muscle pain, and back pain. Children with hypopituitarism may also need adrenal and thyroid hormone replacement and, as they approach puberty, sex hormones.
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Questions to Ask Your Doctor
Are there any tests that need to be performed to rule out any other disease?
Does the child positively have GH deficiency?
What is the cause of the GH deficiency?
How severe is the GH deficiency?
Will you be prescribing hormonal 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?
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