Growth Hormone Deficiency Is Just One Of The Many Causes Of Short Stature In Children
Question: Our son is fourteen years old. He has always been short. In the last few years, he hasn’t grown very much at all. He did not outgrow his clothes or shoes. All of his friends, including boys, have become much taller than him. Otherwise he is healthy and doing well in school. Recently we informed our doctor about our concern. She referred us to a paediatrician. Our son will be getting blood tests and X-rays. He said that our son might be lacking the growth hormone. We went on the Internet and found that the treatment involves giving him injection daily. We are worried sick, because all of us are horrified of needles. Can you give us some advice?
Calm down! Your son may be perfectly fine! Allow your paediatrician to complete the investigation first! In the meantime, read on so that I can explain to you about this, and hopefully calm your fear.
There are many factors that affect the growth of children. Before a child is born, growth of the foetus depends mostly on the health and nutrition of the mother. That is why undernourished women (and women who smoke heavily) have a much higher chance of delivering small babies.
After birth, children’s growth follows a relatively set path with some variations. For the first year, an average child will grow by about 25 cm (this equals 10 inches). In the second year, the growth is around 12 cm. In the third year, this will decrease to 8 cm only. From three until puberty, average children will gain between 4 to 7 cm per year.
Just before puberty, most boys and girls slow down in their growth in height for a short time. Girls start puberty (enlargement of breasts) earlier than boys (enlargement of testes). The puberty growth spurt actually happens about two years earlier for girls than boys. As a result, many girls in grades 5 to 8 are taller than their male classmates. Later in high school, most boys will catch up with their own growth spurt.
The majority of the children that we see because of short stature are totally normal. Most of them have so called familial short stature (FSS) or are simply “late bloomers.”
Children with familial short stature are going to be short because they have short parents. These children are usually born just as big as everyone else. However, during the first 3 years of life, instead of growing as fast as I have mentioned earlier, their growth slows down so that their height will be at or below the bottom of the growth curve. Nevertheless, these children will continue to grow year by year, following the bottom of the curve. They will start their puberty like everyone else, and their ultimate height will be similar to their parents.
The “late bloomers” are very similar to those with familial short stature from birth until puberty. They slow down in height during the first 3 years, and then continue at the bottom of the growth curve. However, these children are a little late in their puberty. Once it starts, their growth spurt brings the height to within normal range, although they may be a little shorter than their parents. Very often, one of the parents (especially the father) also has a history of being a “late bloomer.”
When evaluating a child who is felt to be short, it is important to make sure that one takes into consideration the ethnic background of the parents. The growth curve that we use is derived from information in North America, mostly with Caucasian background. Children from other ethnic background may appear to be abnormally short.
Although the majority of short children are normal and healthy, some serious medical conditions can affect children’s growth. Once in a while, these conditions may not be obvious. They include congenital heart disease, cystic fibrosis, kidney failure, immune deficiency, malabsorption (celiac disease), inflammatory bowel disease, etc. On occasion, severe anorexia nervosa in girls can also lead to stunted growth until the condition is treated.
Children with specific syndromes (like Down syndrome and others), or those with defective growth of bones and cartilage, can also present with short stature. The scope of these conditions is too wide for this column. Suffice to say is that many of these children have abnormal physical features that are not difficult to pick out.
Growth hormone deficiency (GHD) is actually a very uncommon medical condition. This hormone is produced in an area of the brain called the pituitary gland. The production, secretion, and action of this hormone is regulated by many other hormones and receptors. Children who have severe brain infection or brain radiation can develop growth hormone deficiency.
Rarely, children can be born without growth hormone. This can happen because of mutation of the gene that controls the production or function of the growth hormone. It is interesting to know that growth of the foetus before birth does not depend on its growth hormone. Therefore newborns with GHD are completely normal. During the neonatal period, however, they may develop low blood sugar or jaundice. Moreover, these two symptoms are very common in normal newborns, and do not justify testing for growth hormone at this stage.
Children with GHD will fall off the growth curve fairly quickly, within the first year or two of life. In contrast to children with FSS and late bloomers, they continue to fall off more and more below the growth curve. These children, however, will continue to gain weight normally. As a result, many of them appear to be short and relatively chubby. They also tend to have immature features. Most often, puberty is markedly delayed.
You are right in that children confirmed to have GHD require treatment with growth hormone injection. However, the diagnosis needs to be confirmed by rather sophisticated tests that are usually performed by endocrinologists at centres specialized for children.
Down the road, if your son requires growth hormone injection, the staffs at the hospital will teach you how to administer it. Nowadays, there are special “pens” that one can use which will make the injections a lot easier. Special medicated patches can also be put on the skin to reduce the pain from the needle.
I hope I have given you a balanced view about your concern with your son. At the present time, you need to give the paediatrician time to find out the reason behind his short stature. I certainly hope that whatever that is found is not too serious. Good luck!
[Note to Readers: In recent years, World Health Organization (WHO) has developed new growth charts for children, boys and girls, in Canada, that is based on the diverse ethnic background of our country. Many physicians have already adopted the WHO growth charts in monitoring children’s growth.]