Short Stature in Children
(Growth Hormone Deficiency)
Short stature is defined as height below the 3rd percentile for the child’s age (according to standard growth charts for age and height).
Short stature has several causes including growth hormone deficiency, genetic disorders, and chronic illnesses.
Symptoms depend on the child's age and the cause, but typically children have poor overall growth and are short.
The diagnosis is based on a physical examination, x-rays, blood tests, genetic tests, stimulation tests, computed tomography, and magnetic resonance imaging.
Treatment typically includes hormone replacement therapy.
Most children and adolescents who have short stature are short because their families are short, or because their growth spurt came at the late end of the normal range of time for such development. Some children are short because of certain chronic illnesses that affect the thyroid, heart, lungs, kidneys, or intestines. Other children have genetic disorders that affect the bones. However, some have a deficiency of growth hormone.
Hormones are chemical messengers that affect the activity of another part of the body. Growth hormone regulates growth and physical development and is produced by the pituitary gland, which is located at the base of the brain.
Pituitary: The Master Gland
If the pituitary gland does not produce enough growth hormone, abnormally slow growth and short stature with normal proportions can result. Sometimes the pituitary gland also does not produce enough of the other hormones it secretes, such as thyroid-stimulating hormone, adrenocorticotropic hormone, follicle-stimulating hormone, and luteinizing hormone (this disorder is called hypopituitarism).
A deficiency in growth hormone production most often has an unknown cause, but about 25% of cases have an identifiable cause, including
Symptoms of short stature depend on various factors such as the child's age and the cause.
Children have poor overall growth and are short. Some children may have a delay in tooth development. Children who have growth hormone deficiency are short but have normal upper body and lower body proportions. Other abnormalities may be present depending on the cause of the growth hormone deficiency.
There is no single test to show that short stature is caused by growth hormone deficiency. Growth hormone levels in the blood vary widely and are not as useful as other hormone levels in determining why a child's growth is decreased. Thus, doctors make the diagnosis based on a collection of findings.
First, doctors measure the child's height and weight and plot the measurements on age-specific growth charts to determine whether they are growing too slowly. Then they often do x-rays of bones in the hand. Such x-rays can show if the bones are developing normally for the child's age. Children who are simply short have normal bone development for their age. Children who have growth hormone deficiency have delayed bone development. Delayed bone development can also occur in other conditions, such as hypothyroidism and delayed puberty.
It is difficult for doctors to assess growth hormone production because growth hormone production fluctuates throughout the day. As a result, measurement of random growth hormone levels is often not helpful. Instead, doctors do blood tests to measure levels of other substances in the blood that are stimulated by growth hormone. Such substances include insulin-like growth factor 1 and insulin-like growth factor binding protein 3. However, these substances may be affected by other conditions, such as hypothyroidism, celiac disease, and undernutrition, so doctors may do tests to rule out these conditions.
Other laboratory tests are done to look for other causes of poor growth (such as thyroid, blood, kidney, inflammatory disorders, and immune disorders). Genetic testing may be done if doctors suspect the child has a specific syndrome (such as Turner syndrome).
If tests suggest that the child has a pituitary disorder, computed tomography (CT) or magnetic resonance imaging (MRI) of the brain may be done to look for structural abnormalities in the pituitary gland and tumors.
If children have no other cause of poor growth and their growth factor levels are low, doctors typically do a stimulation test. The stimulation test involves giving drugs that stimulate growth hormone production, then measuring growth hormone levels over several hours.
Children are given injections of synthetic growth hormone. The hormones are given until children reach an acceptable height or until children do not grow more than 1 inch (about 2.5 centimeters) in a year. During the first year of treatment, children may grow up to 4 to 5 inches (10 to 12 centimeters), but individual responses vary. Children do not usually have side effects from growth hormone therapy, but some children develop idiopathic intracranial hypertension (pseudotumor cerebri), slipped capital femoral epiphysis, and mild swelling of the limbs that usually resolves quickly (peripheral edema).
Growth hormone also may be used to increase height in children who are short but have normally functioning pituitary glands, but this use is controversial. Some parents feel that short stature is a disorder, but many doctors do not approve of the use of growth hormone in these children. Regardless of the cause of short stature, growth hormone is effective only if given before the bones stop growing.
If identified, brain tumors can be removed surgically, but children are at high risk of hypopituitarism because surgery may damage the pituitary. Children who have hypopituitarism are given hormones to replace the ones they are lacking (see Treatment of Hypopituitarism).