Overview of growth hormone deficiency
Growth hormone deficiency (GHD) occurs when the pituitary gland does not produce enough growth hormone. It affects children more than adults.
The pituitary gland is a small gland about the size of a pea. It is found at the base of the skull and secretes eight hormones. Some of these hormones regulate thyroid function and body temperature.
GHD occurs in about 1 in 7,000 births. This condition is characteristic of many genetic diseases, including Turner syndrome and Prader-Willi syndrome.
You may be concerned if your child does not meet the standards for weight gain and height. Growth hormone deficiency can be treated. Children who are diagnosed early will recover much better. If left untreated, the condition can lead to lower than average height and puberty.
Your body still needs growth hormone after you hit puberty. Once you hit puberty, growth hormone maintains your body’s structure and metabolism. Adults can develop GHD too, but this is not as common.
How do you define “normal” growth?
Growth rates vary significantly from child to child. But measured in height, the average “normal” increase is often described as:
- 0-12 months: 10 inches per year
- 1-2 years: 5 inches per year
- 2-3 years: 3 ½ inches per year
- 3 years from puberty: 2 to 2 inches per year
If your child is less than 3 per cent of the height of child age, it could be an agenda for growth hormone deficiency.
Complications of growth hormone deficiency
Some research suggests that there may be additional complications from the growth hormone deficiency, including:
- The decrease in bone mineral density.
- Increase in cardiovascular risk factors
Symptoms of growth hormone deficiency
Children with GHD are shorter than their peers and have younger, rounder faces. They may also be chubby or have “baby fat” around the abdomen, even though their body proportions are normal.
If GHD develops later in a child’s life, such as from a brain injury or tumour, its main symptom is delayed puberty. In some instances, sexual development is halted.
Many teens with GHD experience low self-esteem due to developmental delays such as short stature or slow maturation. For example, young women may not develop breasts, and young men’s voices may not change as much as those of their peers.
Decreased bone strength is another symptom of GHD. People with low levels of growth hormone may feel tired and without resistance. They may experience sensitivity to hot or cold temperatures.
A variety of psychological symptoms can occur, including:
- Lack of concentration
- Poor memory
- Bouts of anxiety or emotional distress
Causes of growth hormone deficiency
Damage to the pituitary gland or hypothalamus may be the result of an abnormal formation that occurred before your child was born (congenital) or something that occurred during or after birth (acquired).
Congenital growth hormone deficiency can occur if there are mutations in genes for factors that are important in pituitary gland development, or receptors and factors (including growth hormone) along the growth hormone pathway; to date, however, the cause of most of these cases is unknown.
Acquired causes of growth hormone deficiency include:
- A brain tumour in the hypothalamus or pituitary.
- Head trauma
- Radiation therapy for cancers, if the treatment field includes the hypothalamus and pituitary.
- Diseases that infiltrate the hypothalamus or its connection to the pituitary gland, such as histiocytosis.
- An autoimmune condition (lymphocytic hypophysitis).
Diagnosis of growth hormone deficiency
If your child’s height and weight don’t meet the milestones, your paediatrician will look for signs of GHD. They will ask you about your growth rate when you hit puberty, as well as the growth rates of your other children. If they suspect GHD, several tests can confirm the diagnosis.
A blood test can measure growth hormone in the body. However, growth hormone levels fluctuate a lot during the day and night (this is called the “daily variation”). There is not enough evidence to diagnose a blood test with a lower than normal result.
The growth plates are the developing tissue at each end of the arm and leg bones. The growth plates will fuse when development is complete. X-rays of your child’s hand indicate the level of bone growth.
Kidney and thyroid function tests can determine how the body makes and uses hormones.
If your doctor suspects a tumour or other damage to the pituitary gland, an MRI scan will provide a detailed view of the inside of the brain. Growth hormone levels are often tested in adults with a history of pituitary disorders, brain injury, or the need for brain surgery.
The test will determine if the condition of the pituitary gland is congenital or was due to trauma or tumour.
How is growth hormone deficiency treated?
The treatment for growth hormone deficiency is the administration of recombinant human growth hormone by subcutaneous injection (under the skin) once a day. The pediatric endocrinologist calculates the initial dose based on weight, and then bases the dose on response and puberty. The parent is instructed on how to administer the growth hormone to the child at home, rotating injection sites among the arms, legs, buttocks, and stomach. The length of growth hormone treatment depends on how well the child’s height responds to growth hormone injections and how puberty affects growth. Usually, the child is on growth hormone injections until growth is complete, which is sometimes many years.