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Growth Hormone Deficiency
Tuesday, 16 November 2004
Monday, 29 November 2004

What

Growth Hormone Deficiency (GHD) occurs when the pituitary gland, which is located at the base of the brain, produces inadequate amounts of growth hormone. This results in short stature. Short stature can be caused by many different conditions and GHD is only one such condition. GHD has been recognized since the early 1900s.

Who

GHD occurs in approximately one in 5,000 children. It is estimated that 15,000 children in the United States have GHD. All races are affected equally. Males appear to be diagnosed slightly more often than females; however, this may be because they are referred to doctors more frequently than females.

Signs and Symptoms

Children with a complete absence of Growth Hormone from birth are symptomatic in infancy with low blood sugar. This comprises only 5% of children with GHD. Most cases of GHD of an unknown cause, while present from birth, do not show symptoms until later in childhood. Children are usually noticed to be short for their age, beginning around 5 years of age or during puberty (10-13 years for females, 12-16 years for males). While children with GHD are short, they differ from children with dwarfism because their body proportions are normal. Children with GHD are also chubby and may have delayed teeth formation. Males with CHD may have small penises. Children with congenital GHD may have midline facial defects such as cleft palate and a solitary central tooth. If the pituitary gland is unable to secrete any hormone (panhypopituitarism), deficiency of thyroid hormone, cortisol and steroid hormones will also occur.

Possible Causes

The pituitary gland is a marble-sized structure that sits in the middle of the brain, at the base, and secretes various hormones in response to stimuli from another structure called the hypothalamus . These hormones include growth hormone (GH), cortisol (stress hormone), sex hormones, and hormones which stimulate the body to produce thyroid hormone. GH is secreted in bursts or pulses and causes the body to make insulin-like growth factor (IGF), which stimulates bone growth. Most cases of GHD are idiopathic; it is not known why the pituitary gland fails to make enough GH. Unlike dwarfism, GHD is not passed from one generation to another. Sometimes GHD is congenital as the pituitary gland may form abnormally during fetal development. Congenital GHD may be associated with other syndromes. More often, GHD occurs due to an injury to the pituitary gland early in childhood. Injury to the pituitary can result from head trauma, pituitary tumors (craniopharyngioma), brain infections, such as meningitis and tuberculosis, radiation, and rare immunologic disorders like histiocytosis and sarcoidosis.

Diagnosis

The growth rate from age 3 years to puberty in children with GHD is less than 2 inches per year. On the growth chart, the child’s growth will initially slow and eventually stop. Blood tests must be done to exclude isolated thyroid hormone deficiency, kidney disease, and intestinal disease as the cause of the short stature. Chromosomal studies are essential in females to exclude Turner’s syndrome (XO) which can also cause short stature. In GHD, the IGF levels are low but not diagnostic, as malnutrition and chronic diseases cause low IGF as well. MRI of the brain is very important and can reveal pituitary gland tumors or structural abnormalities in 15 % of children with short stature. In GHD, bone age is usually delayed. Bone age can be estimated by taking an X-ray of the wrist and evaluating its bone maturity. GHD cannot be diagnosed by measuring the blood GH level due to its pulsatile excretion and varying blood levels throughout the day. The most reliable way to diagnose GHD is GH provocative testing. A stimulus, such as insulin, is used to stimulate GH production. Peak blood GH level is then measured. If GH is too low, GHD is diagnosed.

Treatment

A pediatric endocrinologist (hormone doctor) is usually involved in the treatment of a child with GHD. Synthetically made GH is available to replace what the body cannot produce. It is given as a single injection daily. Oral medications do not work because they are broken down in the stomach and not absorbed. GH is most effective when given to the child as young as possible and will not work once the growth plates have fused, which occurs during adolescence. It is commonly started at the time of diagnosis and administered for several years until growth plate fusion occurs. Research is ongoing to make long-acting GH which can be given once or twice a month. With therapy, approximately 10 cm more of growth is expected during the first year. Growth slows each subsequent year but normal adult height can be expected with appropriate therapy. The endocrinologist will monitor the child’s growth regularly to adjust dosing. GH acts like an anti-insulin hormone and in some patients can produce elevated blood glucose and worsen any underlying diabetes. Other side effects of GH include severe headaches due to benign brain hypertension (pseudotumor cerebri), which occurs in one in 1000 patients. Swelling of the feet and carpal tunnel syndrome can also occur. If hip pain develops, it must be evaluated quickly to exclude Slipped Capital Femoral Epiphysis (SCFE), where the head of the hip bone becomes displaced from rest of the bone. This is a very serious condition and needs immediate medical attention. GH can also worsen existing scoliosis. Benign breast enlargement prior to puberty occurs in some patients. If the child develops any of these side effects, the GH is stopped and then restarted at a lower dose. There is no increased risk of developing cancer from GH therapy; however, children who have cancer cannot receive GH as it may worsen the cancer. In the past, GH was derived from human brains and some patients developed Mad Cow disease from infected brains; however, GH is only made synthetically now so this risk no longer exists.

Prognosis

Without treatment, children with GHD usually reach an adult height of only 4’9” in men and 4’4” in women. In addition, they have an increased risk for early heart disease, high cholesterol, obesity and osteoporosis. Children with GHD have normal intelligence, but they may become socially isolated due to their short stature. With GH replacement therapy, normal adult height and life span can be expected.

Connect with other parents

In the spirit of community and support, Madisons Foundation offers the unique service of connecting parents of children with rare diseases. If you would like to be connected to other parents of children with this disease, please fill out this brief form.

Weblinks

The Human Growth Foundation
Provides education, support and advocacy. Hormone Foundation www.hormone.org A non-profit organization providing resources for hormone-related conditions.

The Magic Foundation for Children s growth
National nonprofit organization providing support services for the families.

Short Persons Support
Provides support and reference material to persons of short stature.

Google Search for Growth Hormone Deficiency

References and Sources

www.emedicine.com/PED/topic1810.htm www.emedicine.com/med/topic930.htm www.hgfound.org/growth.html kidshealth.org/teen/diseases_conditions/growth/growth_hormone.html

MADISONS Foundation does not endorse the following, but we are publishing it for your information:

Consider participating in a paid, one-time telephone or focus group interview about the impact of growth hormone deficiency in children. For more information about this Novo Nordisk sponsored study, contact Suzanne Alolga, Senior Research Associate with The Brod Group at suzanne@thebrodgroup.net or by telephone at 301-832-7494, and for more information about The Brod Group visit: http://thebrodgroup.net/