Short stature

Synthetic human growth hormone, also known as somatropin, can be used to treat short stature, but its benefits and costs should be considered on an individual basis.

 

Types

Short stature can be the result of many factors. The most common cause is simply coming from a family background of short height, and/or drawing the 'short stick' in the genetic 'luck of the draw'. However, in some cases short stature can also be the result of an underlying medical condition.

Normal short stature

In most cases, short stature is due to either family genetics or a natural delay of growth and puberty, also known as constitutional short stature. These are also known as types of 'idiopathic' short stature, meaning that there is no specific medical condition responsible for below-average height.

Familial short stature

A child's potential height falls in a range that is largely determined by their genes; shorter parents will likely produce shorter children. A child's final height can vary within this range (for example, this writer has a younger brother who is 10cm taller) and some healthy children of shorter parents will be at the short end of the range.

Constitutional short stature ('late bloomer')

Children develop at different rates. Some children are 'small for their age' and will arrive at developmental milestones later than others. In these cases, the child will have attained their final height later than his or her peers, but is otherwise normal.

Systemic disorders

Short stature can be the result of a large number of different medical disorders:

Genetic disorders

Numerous genetic disorders have short stature as one of their characteristics. These can include (but are not limited to):

• Achondroplasia and other forms of dwarfism;
• Down syndrome;
• Kabuki syndrome;
• Noonan syndrome;
• Osteogenesis imperfecta;
• Prader-Willi syndrome;
• Russel-Silver syndrome;
• Turner's syndrome, and;
• Williams syndrome.

Hormone disorders

Hormones regulate growth in the human body. An imbalance in hormone makeup can have many causes, including genetic causes, infections, trauma, and tumors. Some hormone problems can contribute to short stature.

Conditions that can limit growth include:

• Growth hormone deficiency;
• Growth hormone resistance;
• Hypothyroidism;
• Cushing's syndrome, and;
• Excess use of corticosteroid medications.

Development disorders and environmental conditions

Various problems during pregnancy and infancy can contribute to short stature. These can include:

• Intrauterine growth restriction (growth problem in the uterus);
• Fetal alcohol syndrome;
• Failure to thrive and malnutrition;
• Creutzfeldt-Jakob disease;
• Rickets, and;
• Infections before birth;

In addition, various chronic diseases (some of them congenital) can take their toll on a child's body and can contribute towards short stature. These can include:

• Juvenile arthritis;
• Coeliac disease;
• Type 1 diabetes;
• Asthma;
• Inflammatory bowel disease (IBS), and;
• Heart, kidney, liver and blood problems (sickle-cell anemia, thalassemia).

Methods for diagnosis

In order to assess your child's status, your doctor will:

• Measure your child's height against standard growth and development curves;
• Evaluate your child's height based on their age, health status, and family and developmental history;
• Examine your child for physical proportions (weight, sitting height) and outward signs of genetic conditions, and;
• Evaluate your child's bone age from an X-ray image of their hand and wrist.

Your doctor may also want to perform specific tests, including blood tests and growth hormone stimulation, to correctly diagnose the cause of your child's short stature.

Although you may be concerned with your child's present height, it is the pattern of growth that is the most important indicator of health and future height. Thus, your doctor will be interested in how your child has been growing over a period of months and years.

Mid-parental height

In general, expected final height of a child is estimated as the 'mid-parental height', which is the average height of both parents, adjusted for gender.

Mid-parental height is calculated as follows:

For girls - father's height plus mother's height minus 13cm, then divided by two. The range is 8.5cm on either side of this figure.

For boys - father's height plus mother's height plus 13cm, then divided by two. The range is 10cm on either side of this figure.

Thus, for a 170cm father and a 150cm mother, their daughters are expected to be within a 145-162cm range, and their sons within a 155.5-175.5cm range.

The further away a child is from their expected height, the higher the suspicion that there might be an underlying medical problem.

Types of treatment

Short stature is not a disease and does not necessarily require treatment. Whether or not a person with short stature needs treatment depends on their individual circumstances.

Many parents are concerned that their children's height will affect their social lives and their psychological wellbeing. In some cases that could be true, but studies show that this is not always the case.

Human growth hormone treatment

Human growth hormone (HGH), also known as somatropin, is currently a much-discussed substance for various uses, including 'anti-ageing' treatments and improving muscle mass, bone density and reducing body fat.

For many - though not all - cases of short stature in children, treatment with HGH can help to some extent. For idiopathic short stature, a long-term treatment course that takes 4-7 years can contribute between 3-7cm to a person's final height.

For children whose short stature is caused by growth hormone deficiency, HGH treatment is much more effective, and can add up to 30cm to the child's final height.

HGH can also be used in some cases of short stature caused by genetic syndromes, but will not help at all in others (such as achondroplasia). Generally speaking, in cases where HGH can be effective, it is more effective the earlier treatment starts.

In the past, HGH was extracted from human cadavers and was therefore in very limited supply. In addition, HGH from human sources was a potential source of contamination and disease transfer.

In recent decades, recombinant DNA technology has enabled the production of HGH in large amounts. In 2003, HGH was approved in the United States for use in children with idiopathic short stature.

Prevention

There is nothing that can outright prevent short stature. Some forms of short stature are affected by conditions during pregnancy and by the child's own environmental factors, especially nutrition and health. Therefore, the best thing you can do is to provide your child with a safe, stress-free and healthy environment during pregnancy and early development, where possible.