What is growth hormone?

Growth hormone is crucial for normal growth and development.

In our bodies, growth hormone is produced naturally. It is a type of protein that is made by the pituitary gland – a very small gland at the base of the brain. As its name implies, growth hormone is responsible for making us grow. However, it also contributes to many other important functions in the body such as:

 

  • Growing strong and healthy bones
  • Regulating the body’s metabolism, specifically the balance between lean muscle and fat
  • Developing and maintaining the bodies organs
  • General well-being and energy levels
 

Growth hormone works by causing other hormones and factors to be released in the body. These then travel through the bloodstream and cause growth to occur. Specifically, they work on a part of the bones called "growth plates". Growth hormone and growth factors cause the cells in these growth plates to multiply, thus adding to the length of the bones. This increase in length, especially in the leg bones, causes a child to grow taller.

 

What is growth hormone therapy? 

Human growth hormone (hGH) or growth hormone therapy (GHT) is a biosynthetic hormone replacement therapy. It is identical to the natural growth hormone produced by the body. As it is a protein, it needs to be injected in order to work properly. 

GHT is normally used to treat children who are not growing due to an underlying medical condition. Different types of GHT are used in different situations, and you should speak to your health care provider about which GHT is best for you.

Some of the conditions that could be affecting a child's growth include the following:

 

Childhood Growth Hormone Deficiency

As stated above, growth hormone is a naturally occurring protein found in our body. When a child is diagnosed as Growth Hormone Deficient, it means his/her pituitary gland is not producing enough growth hormone. This can either be acquired or caused by hereditary or genetic conditions. Without enough growth hormone, a child does not grow the way he/she should. Growth hormone is also crucial for bone development and healthy muscles. It is important that children who are growth hormone deficient are identified and diagnosed as early as possible so they can receive the necessary treatment to help them grow and develop. When a GHD child is diagnosed and treated early, adult height is expected to be normalized.

The most common treatment is growth hormone therapy (GHT).  GHT is identical to the growth hormone made in the body and is a good replacement when the body does not make enough of its own growth hormone. Most children will only need GHT until they finish growing, or for a couple of years afterwards. In a few rare cases, they might need to continue treatment as adults.

 
Small for Gestational Age (SGA)

If a baby is born SGA, it means that he/she is smaller than he/she should be in: 

 

  • Length
  • Weight
  • Length and weight 
  • Head circumference
 

Most babies born SGA will catch-up to average length and/or weight by two years of age. In some cases, they will not catch-up and will require growth hormone therapy (GHT) to help them grow.

Children born SGA who fail to catch-up may also have additional health problems as they grow older. That is why it is important to ensure these children are identified at birth and followed by doctors so any problems are identified early.

 

Turner syndrome

Turner syndrome (TS) is a genetic disorder that can affects girls. TS happens when one of the two X chromosomes in girls is either missing or only partly there. TS is rare and only 1 in 2,500 baby girls is born with it. TS is often missed until the girl reaches puberty and her period does not start as expected.  

TS has an impact on many different aspects of a girl's health, including her ovaries, heart, and ears. It also affects the way she grows, and growth retardation can be one of the first recognizable signs of TS.  

Girls with TS may require many different medical treatments, like replacement therapy or growth hormone therapy to help them grow. This is why it is important that TS is identified early - so girls can get the appropriate medical treatment they need. 

 

Noonan syndrome

Noonan Syndrome (NS) is a genetic disorder that occurs in both boys and girls. NS affects the body in many different ways, including physical features like webbed neck, dropping eyelids and low-set ears. It also affects the heart, and in many cases it is first identified due to a heart murmur. NS can also affect the testes in boys.  

These different physical displays can vary in level of "severity", and some children with NS may not display any of the more noticeable physical characteristics. However, one thing that is common among most NS children is very short height. Growth hormone therapy (GHT) is often given to help children with NS grow. Studies have shown that when treated with GHT early enough, the majority of children with NS can reach an adult height within the normal range.

Children with NS will probably require different types and levels of medical care throughout their lives. Early identification and treatment is crucial to their overall health and well-being. 

 

Skeletal dysplasia

Skeletal dysplasia is a term used to describe a range of more than 200 very rare conditions that affect cartilage and bone growth. Achondroplasia (ACH) and Hypochondroplasia (HCH) are two of the more common skeletal dysplasias - but both are still very rare.  They are known as "short limb" dysplasias because they mostly affect the size of the arms and legs. 

In some children with ACH or HCH, growth hormone therapy (GHT) may be an option to help them grow. This  may result in some length gains in the legs and arms.

 

Chronic Renal Disease

Chronic Renal Disease (CRD), also called chronic renal failure (CRF), is a condition in which a child's kidneys are not working well. A child may be born with poorly functioning or malformed kidneys, or may develop kidney problems later in childhood due to other conditions like diabetes. 

Chronic kidney disease affects the kidneys' ability to filter blood which leads to a build-up of fluid and waste products in the body. This condition affects most body systems and functions and results in:

 

  • High blood pressure
  • Low blood cell count
  • Vitamin D deficiency and poor bone health
 

CRD can even affect a child's growth. In most cases, growth can be improved by better control and management of the underlying disease. However in more severe cases, growth hormone therapy (GHT) may be prescribed to help these children grow.

 

Prader-Willi syndrome

Prader-Willi syndrome (PWS) is a genetic condition that can affect boys and girls. It is a rare condition, and while hard to say how many children are born with PWS, it is usually estimated as 1 in 30,000 births.  

PWS is usually described as having two phases. Phase 1 is from birth until 2 years of age. During this time, children with PWS are very weak, have low muscle tone, and do not nurse well. Phase 2 can happen anytime between 1 and 6 years of age and starts when a child develops an abnormal interest in food and eating. This change is not sudden but will happen over a period of time and will lead to obesity at a young age. 

Some children with PWS may have low levels of growth hormone and will not experience the normal growth spurt at puberty. Growth hormone therapy (GHT) may be prescribed to help these children grow.

 
Adult Growth Hormone Deficiency

As adults, our bodies continue to produce and need growth hormone in smaller amounts even though we have finished growing. In adults, growth hormone is important for other reasons, including heart health, strong bones, and fat to muscle proportion. Growth Hormone Deficiency can also affect adults - either when children who were severely growth hormone deficient still require GHT as adults, or when adults become growth hormone deficient due to illnesses or accidents affecting the pituitary gland (like a tumour or severe head injury). 

 


Important Note: The content of this website is not intended to be a substitute for professional medical advice, diagnosis or treatment. Do not disregard your doctor's advice or delay in seeking it because of something you have read in this website.

HQMMA/NT/0815/0140 October 2015