Growth hormone is produced by the pituitary gland located deep inside the brain. Instructions for producing growth hormone come from other parts of the body, for instance, the hypothalamus. If there is a problem with the hypothalamus, the pituitary or the connection between the two, the release of growth hormone will be affected, leading to growth hormone deficiency.
Growth hormone is also responsible for releasing other hormones (chemical messengers), such as telling the liver to produce insulin-like growth factor (IGF 1) which is essential for growth in childhood.
What causes growth hormone deficiency?
In many cases, the cause of growth hormone deficiency cannot be identified so it is described as idiopathic. We know that growth hormone deficiency is not inherited and that it can be present at birth or develop later in childhood alongside other conditions, such as septo-optic dysplasia. We also know that it is more common in males than females, although more research is needed to understand why this should be the case.
What are the signs and symptoms of growth hormone deficiency?
The main symptom of growth hormone deficiency is that growth slows down or stops from the age of two or three years onwards. Growth hormone deficiency may be suspected through routine monitoring using growth charts or it may become more obvious when a child starts nursery or school and is much shorter than other children in the class.
Although children with growth hormone deficiency grow slowly, they grow in proportion – that is, the length of their arms and legs stay at the same ratio to their chest and abdomen. Their face may also look younger than their actual age. They may seem chubbier than other children – this is due to the effect of growth hormone on fat storage within the body. Puberty may happen later than usual or not occur at all.
How is growth hormone deficiency diagnosed?
Growth hormone deficiency is diagnosed using blood tests to measure the levels of certain hormones within the blood. Careful monitoring of height and growth is also carried out using standard growth charts that show a child’s height in relation to average rates for children of the same age and gender. A DEXA scan may be useful to working out a child’s bone age, as can a hand and wrist x-ray. If a problem with the pituitary or hypothalamus is suspected, a head magnetic resonance imaging (MRI) scan may be suggested.
How is growth hormone deficiency treated?
Growth hormone deficiency treatment and monitoring is best carried out by a paediatric endocrinologist (doctor specialising in children’s hormones). Growth hormone deficiency is treated by replacing the missing hormone with a man-made version.
The aim of growth hormone therapy is to treat growth hormone deficiency by returning the child to the normal growth curve so reaching the height that would be expected taking into account parents’ height and other factors. The dose of growth hormone will be calculated according to your child’s weight so will change over time. This dose will balance the results expected against potential side effects. Growth hormone therapy is given by injection under the skin (subcutaneously) in a daily dose.
Growth hormone replacement does not work for all children, but in most cases, if started early, they can reach normal adult height.
What happens next?
Children with growth hormone deficiency need regular follow up so that the dose of growth hormone can be adjusted as they increase height and weight. They will also need regular monitoring, not only for the effects of treatment but for any side effects that might occur. In most cases, teenagers will need to transfer to an adult endocrinologist for life-long monitoring as continuing to have the injections, even after growth has stopped, can help protect various body systems, particularly stopping the bones becoming weakened (osteoporosis).