Someone has to be the smallest kid in their year at school. But what if that’s your child – should you be concerned?
One of the most common referrals to Paediatric Endocrine clinics is because of parents worrying that their child is too short for their age. Although all children grow at different rates, and some will naturally be much taller or smaller than others, there are also some conditions that can prevent a child from growing as they otherwise would - which can be rectified with proper treatment.
But how can you tell the difference between a child who is naturally short and one who would benefit from being treated? We spoke to Professor Mehul Dattani, Head of Paediatric Endocrinology at Great Ormond Street Hospital (GOSH), who participated in the 15th SEHA International Paediatric Conference, about short stature in children – what’s normal, and what is not.
What does it mean to be ‘short’?
The term ‘short stature’ refers to any child who has a height well below the average for his or her age, sex and racial group - usually below the line marking the third percentile (or some people say the 5th percentile) when plotted on a growth chart.
How to use a growth chart
Growth charts use lines to display an average growth path for a child of a certain age, sex, and height. Each line indicates a certain percentage of the population that would generally be that particular height at a particular age.
For instance, if a boy has a height that is plotted on the 50th percentile line, it indicates that approximately 50 out of 100 boys his age are shorter than him, and 50 out of 100 boys are taller than him. If a boy has a height that is plotted on the 30th percentile line, it indicates that approximately 30 out of 100 boys are shorter than him, and 70 out of 100 boys are taller than him.
Children do not usually follow these lines exactly, but the idea is that their growth over time is roughly following these lines if everything is normal. A child that has a height plot that is below the 3% line is considered to have ‘short stature’ compared to the general population.
When is being short a sign that something might be wrong?
There is nothing wrong with being in the third percentile for height if that’s where your child consistently stays and it makes sense genetically, says professor Dattani. “Children who are short because their parents are short (familial short stature) or due to no obvious underlying cause (idiopathic short stature) usually grow at a normal rate for their age, or a slightly slower rate, and they track along a centile line on the growth chart,” says professor Dattani.
However if your child suddenly drops down on the growth curve as they age (dropping from the 30th to the 5th percentile for instance), this can be a warning sign that there may be an underlying medical condition affecting growth.
But it’s important not to be alarmed unnecessarily. “In the first three years of life children do tend to catch up and down,” says Professor Dattani, meaning that they have growth spurts and slow-downs, which are nothing to worry about. “Thereafter they should follow their own trajectory along the centile charts,” says professor Dattani.
“If a child follows their own trajectory, and if the growth rate is normal for their age and gender, as well as their pubertal status, then the family can be reassured that their grow is probably normal for them."
Sometimes, the child is growing at a normal rate, but is short for the family, and the bone age (assessed from an Xray of the non-dominant hand and wrist) is delayed. "This suggests a diagnosis of growth delay which is good news generally, as the child will catch up later, usually at the time of puberty, and will likely end up with a normal height for the family," explains professor Dattani.
• 0–12 months: Growth rate is the fastest in the first year of life, when children grow about 10 inches (25 cm)
• 1–2 years: Children grow about 4 to 5 inches (13 cm)
• 3 years to puberty: Children grow about 2 1/2 inches per year (5-6 cm)
The onset of puberty differs for boys and girls, although it is often between the ages of 8 and 14 years (average of 11 for girls and 12 for boys). Girls will grow roughly 2.5 to 4.5 inches (5 – 11cm) yearly during puberty; boys will grow three to five inches (7-12cm) yearly.
What else could be causing a child’s short stature?
There are many potential causes for a child failing to grow as tall as they genetically should do, but it’s worth remembering that most children who have short stature have no medical condition and are growing at a rate that is normal for them.
Causes of short stature not associated with disease include:
- Familial short stature that is inherited
- Constitutional delay in growth (whereby the child is short in childhood but will have late puberty and end up being a normal height as an adult)
- Idiopathic short stature (no cause can be identified but the child is healthy)
Health conditions that can cause short stature include:
- Nutritional deficiencies or malnutrition.
- Chronic medical conditions or disorders of the digestive system, kidney, heart, lung, bone or liver disease.
- Hormone disorders, such as hypothyroidism (low thyroid hormone); excessive cortisol production or exposure (Cushing Syndrome); growth hormone deficiency, insufficiency or resistance; diabetes.
- Congenital conditions, such as intrauterine growth retardation; prenatal infections; alcohol abuse during pregnancy; or other factors, such as genetic (chromosomal) or skeletal abnormalities
WHAT CAUSES GHD?
There are several causes of GHD, says professor Dattani: “These include congenital causes, those associated with midline brain defects, or those associated with craniofacial defects. Acquired causes can be associated with perinatal or postnatal trauma, brain tumours such as Craniopharyngioma, infiltrative or inflammatory lesions such as Langerhans Cell Histiocytosis, infections such as meningitis, and cranial irradiation or chemotherapy for brain tumours.”
WHAT'S THE DIFFERENCE BETWEEN A CHILD WITH GHD AND A NATURALLY SHORT CHILD?
A child with GHD often manifests a range of clinical features, explains professor Dattani. “GHD may present early in life with hypoglycaemia (low blood glucose). Later on. it may present with poor growth, classical facial features with a prominent forehead and a depressed nasal bridge, a high pitched or squeaky voice, slow hair and nail growth, and a low muscle tone. The growth rate is usually poor, and the child drops through centiles on the growth chart and is often very short for the family.”
On the other hand, children who are short because their parents are short (familial short stature) or due to no obvious underlying cause (idiopathic short stature) usually grow at a normal rate for their age, or a slightly slower rate, and they track along a centile line on the growth chart. “The basal markers of GH secretion, Insulin-like Growth Factor 1 (IGF1) and Insulin-like growth factor binding protein 3 (IGFBP3) are low in GHD, but normal in familial or idiopathic short stature.”
HOW IS IT TREATED?
Children are often diagnosed with GHD during childhood or at the time of puberty, when they fail to grow at the rate that is expected for a pubertal growth spurt, says professor Dattani. “GHD can be easily treated with recombinant human growth hormone injections, which need to be given daily currently. The injections are continued until the child stops growing (<2cm/year). At that stage the young person is usually retested for GHD, and between 25-75% of adolescents with previously treated GHD will reverse their GH secretion and have normal GH secretion. In those with persistent severe GHD, there is an indication to continue with low dose GH which has beneficial effects on body composition, metabolic status and possibly the cardiovascular system in adults. Severe GHD cannot be cured and will usually persist.
Can a naturally short child be treated with growth hormone so they will grow taller?
No – growth hormone therapy (injecting children with growth hormone) is only safe and effective if they have Growth Hormone Deficiency, says professor Dattani, or if they have a medically diagnosed condition. “Growth Hormone Therapy is a safe and effective treatment for GHD. However, its safety in familial short stature or idiopathic short stature has not been established, and it certainly is not an effective treatment for these conditions.”
• Add the mother's height and the father's height in either inches or centimeters.
• Add 5 inches (13 centimeters) for boys or subtract 5 inches (13 centimeters) for girls.
• Divide by two.
Another way to estimate a child's adult height is to double a boy's height at age 2 or a girl's height at age 18 months.
Remember, a child's height is largely controlled by genetics. It's also important to note that children grow at different rates. Some children begin their growth phases early, while others are late bloomers.
Source: Mayo Clinic