Overview
Restricted growth, sometimes known as dwarfism, is a condition characterised by unusually short height.
There are 2 main types of restricted growth:
- proportionate short stature (PSS) – a general lack of growth in the body, arms and legs
- disproportionate short stature (DSS) – where the arms and legs are particularly short
As well as being short, some people with restricted growth also have other physical problems, such as bowed legs or an unusually curved spine.
But most people don't have any other serious problems and are able to live a relatively normal life, with a normal life expectancy.
What causes restricted growth?
Causes of PSS
The most common cause of PSS is being born to small parents, but it's sometimes the result of the body not producing enough growth hormone.
Certain genetic syndromes, such as Turner syndrome, Noonan syndrome and Prader-Willi syndrome, can also cause PSS.
Causes of DSS
A rare genetic condition called achondroplasia is the most common cause of DSS.
It causes poor bone growth, resulting in short upper arms and thighs.
It doesn't always run in the family – many children with achondroplasia have parents of normal height.
The Restricted Growth Association UK has more information about achondroplasia and other rare types of restricted growth.
Diagnosing restricted growth
Restricted growth may be diagnosed before a child is born, soon afterwards, or when growth problems become more obvious as they get older.
Growth hormone deficiency is usually diagnosed using growth hormone stimulation tests.
Medicine is injected into a vein or muscle to cause an increase in growth hormone levels in the blood. A lower than normal level indicates a deficiency in growth hormone.
A brain scan will be needed to look at the pituitary gland (which produces growth hormone) if blood tests show low levels of growth hormone.
If one or both parents have a family history of a condition that causes short stature, their baby can be tested for this during pregnancy (prenatal diagnosis).
Treatment for restricted growth
Treatment with growth hormone injections may benefit some people with restricted growth and can help a child with the condition grow more than they otherwise would.
In cases of DSS where the legs are particularly short, a leg-lengthening procedure is sometimes used, but there's some uncertainty about its safety and effectiveness.
Symptoms
Some people with restricted growth (dwarfism) have health problems. But for many, the only sign is short height.
Proportionate short stature
People with proportionate short stature (PSS) grow very slowly and have a general lack of growth throughout the body. The body, legs and arms are all shorter than normal.
PSS may not be noticeable until later in childhood or puberty.
Any other symptoms the person has will depend on the underlying cause of PSS.
Disproportionate short stature
In people with disproportionate short stature (DSS), the arms and legs are particularly short.
People with achondroplasia, one of the most common causes of DSS, typically have:
- a normal-length body with short arms and legs
- a large head with a prominent forehead and flat nasal bridge
- short and wide hands and feet
- short fingers and toes
Some people with achondroplasia also have:
- bowed legs, which may cause ankle or knee pain
- an abnormally curved spine (kyphosis) or (scoliosis)
- a build-up of fluid around the brain (hydrocephalus)
- repeated ear infections, which can cause hearing difficulties
- irregular breathing at night (sleep apnoea), which can interrupt sleep and cause excessive sleepiness during the day
- numbness and weakness in the legs, caused by compression of the nerves in the spine
Treatment
Some people with restricted growth (dwarfism) may be able to have growth hormone treatment or leg-lengthening surgery.
Growth hormone medication
The National Institute for Health and Care Excellence (NICE) recommends human growth hormone treatment (somatropin) as an option for children whose poor growth is linked to:
NICE also recommends it for some children who are born small and fail to catch up in growth by the age of 4 or later.
Somatropin treatment should be started and monitored by a child health specialist with expertise in managing growth hormone disorders in children (paediatric endocrinologist).
The hormone is given as a single daily injection, which can usually be done by a parent, carer, or by the child when they're old enough.
Skin reactions are the most commonly reported side effect. In very rare cases, the treatment is associated with persistent severe headaches, vomiting and vision problems.
Children with growth hormone deficiency respond very well to somatropin and may be able to reach a relatively normal adult height. The effectiveness in children with other conditions can vary.
Somatropin treatment may stop once your child stops growing, but in some cases it may be given into adulthood because it can sometimes help prevent problems such as weak bones (osteoporosis).
Leg-lengthening surgery
If you have particularly short legs, a leg-lengthening process known as distraction may be an option.
Using surgery, the leg bone is broken and fixed to a special frame. With the support of the frame, the leg is stretched, allowing new bone to form in between the 2 broken ends of bone.
Over time, this bone gets stronger until it's able to support your weight.
Distraction can sometimes result in a significant increase in height, but it's a lengthy treatment and has a risk of complications, so isn't always recommended.
Some people have pain during or after the limb-lengthening procedure.
Other possible complications include:
- poor bone formation
- fracture
- infection
- bone lengthening at an inappropriate rate
- blood clots
There's also some uncertainty about the safety and effectiveness of the procedure.
It's therefore important that you understand exactly what it involves and talk to your surgeon or doctor about the risks if it's suggested as a possible treatment for you or your child.
Support and treatment for related problems
As restricted growth can be associated with several related conditions and problems, affected children and adults will be cared for by a multidisciplinary team of healthcare professionals.
This team may include:
- a paediatrician (child health specialist)
- a nurse specialist
- a physiotherapist
- an occupational therapist
- a dietitian
- an audiologist (hearing specialist)
- a speech and language therapist
- a neurologist (specialist in nervous system disorders)
- an orthopaedic surgeon
- a geneticist
You may have regular check-ups with members of your care team so your health can be monitored and any problems that develop can be treated.
Help and support
If you or your child has restricted growth and you'd like to speak to someone for advice and support, the Restricted Growth Association UK has a helpline you can call on 0300 111 1970.
The RGA website also has more information for parents.