Somatotropin deficiency in childhood (somatotropin is a different name for growth hormone); hypopituitarism in childhood (a broader term covering deficiencies of various hormones originating from the pituitary gland); COGHD
Growth hormone is a hormone essential to growth and development. It is produced in a gland at the base of the brain called the pituitary gland. Growth hormone is transported in the blood all over the body to help with its many, complex functions, the most important of which, in childhood, is growth. If a child does not have enough growth hormone, then the speed of growth is much slower and final height is reduced.
A child can be born with this defect or acquire it later on in life. The cause of the majority of cases of childhood-onset growth hormone deficiency is not known. This is known as idiopathic.
In a small proportion of cases, the cause is genetic or syndromic. Genetic means that a problem has occurred in a specific gene involved with production of growth hormone. Syndromic means that during development in the mother’s womb, a problem occurred with brain development. In some cases this also involves the pituitary gland and it can therefore affect growth hormone secretion.
A child, similarly to an adult, can also develop this condition later in its life as a result of a brain tumour and its treatment, brain injury or infection. See articles on hypopituitarism and adult-onset growth hormone deficiency for more information.
Signs and symptoms vary depending on the severity of the defect and the child’s age. The symptoms from very mild insufficiency will show later in a child’s life. Babies born with growth hormone deficiency have a normal newborn size and generally show no signs at all, but can have low blood sugar levels or yellowish skin colour, which can be due to causes other than growth hormone deficiency.
In both early and later childhood, growth hormone deficiency is identified as slow growth compared with other children of the same age. Again, this can be more or less obvious. Often, the children look chubbier, shorter and younger for their age. Poor development of the bones in the middle of the face is also a sign of inadequate growth hormone. Body proportions and intelligence remain normal.
Growth hormone deficiency can be associated with deficiencies of one or several other pituitary hormones, for example those that control the thyroid or adrenal glands. Signs and symptoms may also be present because of these additional hormone deficiencies and there are many conditions that can account for poor growth and short stature that have nothing to do with growth hormone deficiency. This can make reaching the correct diagnosis a challenge.
Growth hormone deficiency has been identified in about 1 in every 3,800 babies. Additionally, some children acquire it later in their life as a result of a brain tumour, brain operation, radiation therapy, injury or infection.
Most incidences of childhood-onset growth hormone deficiency occur as isolated cases and are not inherited. However, it can occasionally run in families. A number of genes have been identified that cause growth hormone deficiency. Brothers and sisters are affected in around 3% of the cases.
The child will show slow growth compared with other children of the same age when his height and weight are plotted on a growth chart. Doctors will need to ask many questions regarding the family and other health issues.
A number of specific blood tests will be taken in the outpatients department of a hospital or at a GP surgery to run this information against a wide range of possible conditions causing slow growth. During most of the day, growth hormone levels are very low in the blood, making single blood tests of growth hormone of limited value. Measurement of the hormone insulin-like growth factor-1 is a good indicator of growth hormone deficiency in childhood, but can be influenced by abnormalities of the liver, kidneys, thyroid and nutrition.
It is more accurate to focus on testing the individual child’s ability to produce growth hormone. This can be performed in several ways, but generally involves giving the child something to stimulate release of growth hormone, and then levels of growth hormone are checked by blood tests over the following 2–3 hours. An X-ray of the bones helps to estimate the potential for further growth. The overall assessment can be complex and requires an expert doctor with special interest in children's hormones (a paediatric endocrinologist).
Growth hormone has been manufactured since the 1980s. It is available only as a daily injection into the fat underneath the skin, although there are some injection devices available that do not involve needles. This injection is normally given in the evening to fit in with the body’s natural cycle for producing growth hormone. Expert monitoring of the correct dose, and advice on the range and most appropriate injection device is very important. The dose prescribed will vary from patient to patient, according to the weight and size of the child.
Generally there are few side-effects to the treatment; these occur more frequently if the dose is too high. Side-effects can include soreness and lumpiness of the skin at the injection site. Headaches, fluid retention, joint and muscle pains have also been reported. Growth hormone cannot be given to children with untreated cancer. If the patient is concerned about any side-effects, these should be discussed with the endocrinologist or GP.
Treatment should start early and continue as long as the child is growing to prevent abnormally short stature and the consequent physical and psychological problems this can cause. Treated children generally achieve relatively normal height and development as long as they are diagnosed early enough to give time for ‘catch-up’ growth to occur. Like many medical conditions, this one requires regular specialist follow-up as an outpatient.
In the past, growth hormone treatment was stopped at the end of growth. It is now clear that growth hormone contributes to both bone mass and muscle mass reaching the best possible level, as well as reducing fat mass during development to an adult. The specialist is therefore likely to discuss the benefits of continuing growth hormone after growth has completed until age 25 to make sure bone and muscle mass reach the best possible level. In addition, growth hormone has been linked to a sensation of wellbeing, specifically energy levels. There is evidence that 30–50% of adults with growth hormone deficiency feel tired to a level that impairs their wellbeing. These adults may benefit from lifelong treatment with growth hormone.
Last reviewed: Dec 2014