What are the growth hormone disorders?
There are two different types of growth disorders: growth hormone deficiencies and excessive growth hormone. Growth hormone (or GH) is responsible for us humans growing from children to adults. Contrary to popular belief, however, it does not solely perform this function, it is also responsible for the following:
- Bone length
- Muscle growth
- Increasing concentration of free fatty acids and glucose
- Cell reproduction and regeneration
- Increasing concentration of protein via influencing insulin-like growth factor
I’ll be going through both extremes of the scale here: first I’ll address GH deficiency and then I’ll be tackling GH excess.
Growth Hormone Deficiency
Growth hormone deficiency, as the name suggests, is a deficiency of growth hormone. It is produced in the anterior pituitary gland and its main cohort, insulin-like growth factor (IGF-1), is produced in the liver.
How is it picked up?
The vast majority of cases of GH deficiency are diagnosed in young children, but it can also occur sometimes within adults. As part of childhood development, when a kid is taken to the doctor’s surgery with their parents or adult guardians, their growth is compared against a chart, much like the one alongside. If the growth rate turns out to be significantly lower than that of both their parents, then GH deficiency is suspected.
If it is picked up in childhood, would it affect their appearance or intelligence?
Despite the child growing at a slower rate than normal, as the above picture demonstrates, the body proportions would be normal, or in some cases (depending on genetics), would have a chubbier build and a youthful appearance in their face. Occasionally, GH deficiency is picked up inadvertently through examination of cleft palates or cleft lips. GH deficiency does not affect intelligence.
What about if it is tracked later on in life?
If the deficiency is not caught until adolescence, puberty may be delayed, or, like Peter Pan, people with this condition may never fully develop into adults.
What are the root causes of GH deficiency?
Most of the time GH deficiency would be described as idiopathic. What that entails is that the root cause of the disease is unknown. However, there are some external or internal triggers that may lead to the development of GH deficiency: such triggers include:
- Severe head injury
- Radiotherapy used to treat brain cancer
- Tumours of the pituitary gland and/or hypothalamus
Is the disorder referred to by any other name?
There are several other names that refer to deficiency of growth hormones: they include the following:
- congenital GH deficiency
- isolated GH deficiency
- acquired GH deficiency
- pituitary dwarfism
- panhypopituitarism (lack of all pituitary hormones)
Can GH deficiency be treated?
If it caught early enough, yes: the prognosis for the person is better the earlier that they are diagnosed. It is likely that children diagnosed with GH deficiency within the first few years of life will achieve an adult height within the normal range: albeit they may fall within the short end of the normal spectrum.
How is it treated?
GH deficiency is treated by means of once-daily injections of synthetic growth hormone: they are reasonably safe and the side effects are usually mild. Side effects of this injection include aching muscles and joints, swelling due to retention of fluid and headaches. Injection via growth hormone is effective in most cases, however it is not guaranteed that it will work in every case.
Are there any other ways growth hormone is used?
Yes: some athletics use synthetic growth hormone in the popular belief that it will better their physique, and is spread around via the black market, as it is seen as illegal. Despite this widespread belief, however, it is more than likely to be a waste of money as that is not what it is designed to do.
Acromegaly: what is it?
Acromegaly happens when excess GH from the anterior pituitary gland is produced. It happens after the process of puberty has closed the epiphyseal plates located in each of the long bones. As this picture shows, in childhood, this plate is made of flexible cartilage, but it solidifies through the teenage years, and by the time you hit adulthood, it is solid bone and the only evidence that this conversion has occurred is a line across the bone.
What is seen?
If the GH is secreted in excess before puberty starts, the person grows to a height well above average, and the condition is known as gigantism. However, if puberty is allowed to pass as normal, the person may be within the normal range of height, however there is overgrowth present within their bones and soft tissues. Some of the features that may be affected include:
- Mandible (chin bone)
- Teeth (gaps present)
Unfortunately, there are also side effects from this condition that are present in classic cases of acromegaly. Such effects include:
- Arthritis in the spine due to overgrowth
- High blood pressure (hypertension)
- Pre-diabetes (i.e. glucose intolerance) or full-blown diabetes mellitus
- Athersclerosis i.e. growth of fatty plaques within arteries
- Muscle weakness due to myopathy (muscular abnormalities)
- Sleep apnoea (stoppage of breathing during sleep)
- Hyperhydrosis (excessive sweating)
- Heat intolerance
- Organomegaly (enlargement of organs)
Can acromegaly affect the life span?
Due to some of the potential side effects, yes: the life span may be shortened due to either the hypertension, athersclerosis or the diabetes.
How is acromegaly diagnosed?
Growth hormone is tracked in the serum (the non-cellular component of blood). There are two potential ways of diagnosing acromegaly: the first is the gold standard (the test that has the most reliability), and the second is the alternative method.
- It is diagnosed in the lab with a biochemistry analyser by the results showing up with an elevated GH level that is not suppressed with additional glucose loaded in. However, this does not always happen. In that case, the second method is applied.
- Occasionally the results of GH can turn out be falsely normal. In this case, the lab staff will check the IGF-1 (insulin-like growth factor) levels: if this is elevated, acromegaly can also be diagnosed.
Can acromegaly be treated?
Yes, albeit it is not always easy: the course of treatment taken is dependent on the size of the tumour which caused the excess GH in the first place. The treatment options include:
- Removal of the tumour via surgery: can happen in one hit if the tumour is small enough, but some of the tumour may remain if the tumour is large or has invaded too far.
- Irradiation focused on the tumour
- Somatostatin analogs (somatostain is otherwise known as growth-hormone inhibiting hormone).
- Dopaminergic agnosists (helps activate dopamine receptors, but is only useful if the tumours secretes excessive prolactin as well as excessive GH)