Half of all children are shorter than average. That is what average means, and it is worth saying out loud before anything else, because a great deal of unnecessary anxiety begins with a parent comparing their child to the tallest child in the class.
Still, short stature is the single commonest reason a child is referred to me, and a minority of those children have something identifiable and treatable. The job is telling them apart.
The three questions
Almost every assessment reduces to these.
1. Is the child short for the family?
Short parents have short children, and that is not a disorder. Calculate the mid-parental height:
- Boy: (mother’s height + father’s height + 13 cm) ÷ 2
- Girl: (mother’s height + father’s height − 13 cm) ÷ 2
Allow roughly ±8–9 cm. A child tracking inside that range is usually doing exactly what their genes intended.
2. Is the growth rate normal?
This matters more than height itself. Between the age of about four and the start of puberty, a healthy child gains roughly 5–7 cm a year. Consistently under about 4–5 cm a year deserves investigation regardless of which centile the child is sitting on.
You cannot know the rate from one visit. It needs two accurate measurements at least six months apart, and preferably a year.
3. Is the child crossing centiles downwards?
A line drifting down through the centile bands after the age of two is the classic pattern that brings a child to an endocrinologist. Where the line sits matters far less than which way it is heading.
The common, benign explanations
Together these account for the majority of referrals.
Familial short stature. Short child, short parents, normal growth rate, bone age matching chronological age, puberty on time. Adult height will be short and normal.
Constitutional delay of growth and puberty. The late bloomer. Growth is slow but steady, the bone age is behind, puberty arrives late, and a parent very often tells the same story about themselves. Adult height usually lands in the expected family range. Treatment is not always needed, but a short course can be offered when the social cost of being fifteen and pre-pubertal is high, and that cost is real.
Small for gestational age with catch-up. Babies born small who catch up in the first two years. About one in ten does not, and that subgroup does need endocrine review.
The causes worth looking for
These are what the investigation is actually hunting.
- Hypothyroidism. Often strikingly slow growth with weight gain, which is a distinctive combination
- Growth hormone deficiency. Isolated, or part of wider pituitary dysfunction
- Coeliac disease. Sometimes with no gut symptoms at all
- Chronic disease. Kidney, heart, liver, inflammatory bowel disease, poorly controlled asthma on high-dose steroids
- Turner syndrome. Every short girl with an unexplained slow growth rate warrants a karyotype, even without other features
- Skeletal dysplasias. Suggested by disproportion, which is why sitting height and arm span are measured
- Excess glucocorticoid, including from long-term inhaled or topical steroids
- Nutritional deficiency, still common and still frequently missed
What the first appointment involves
No tests on day one, usually. The history does most of the work: pregnancy and birth weight, milestones, illnesses, medications, diet, family heights and pubertal timing, and above all every previous measurement you can produce.
Then careful measurement: standing height on a proper stadiometer, weight, sitting height, arm span, head circumference, and an assessment of pubertal stage.
If investigation follows, it is typically an X-ray of the left hand and wrist for bone age plus a first-line blood panel: thyroid function, coeliac screening, a blood count, kidney and liver function, IGF-1, and a karyotype in girls. Growth hormone stimulation testing comes later, and only if the first round points that way. It is not a screening test.
About growth hormone
It is a genuinely transformative treatment for the children who need it: growth hormone deficiency, Turner syndrome, some children born small who fail to catch up, and a small number of other specific indications.
It is a daily injection, usually for years, it requires regular monitoring, and it is expensive. It is not a height booster for a healthy short child, and it does not work well as one. Anyone offering it without a documented diagnosis and a proper workup is not doing you a favour.
When to seek an opinion
- Growth rate under 4–5 cm a year in a school-aged child
- Crossing downwards through centile bands over more than a year
- Height well below the mid-parental range
- Short stature with disproportion, dysmorphic features, or delayed puberty
- Any short girl with no explanation
- Short stature with headaches or visual symptoms, promptly
And if none of these apply, and your child is simply a shorter child in a family of shorter people, growing steadily along their own line: that is a good chart, and it is worth being told so.
General information, not advice about an individual child. Bring the growth records to a paediatrician or paediatric endocrinologist.