Parents are often concerned about their children's growth, especially if they seem to be shorter than other children that are the same age. While there are many medical causes for being short and having poor growth, including growth hormone deficiency, hypothyroidism, Turner syndrome, inflammatory bowel disease, kidney problems, malnutrition, etc., most children who are short are normal. They may have genetic short stature or a constitutional growth delay.
Children normally grow at a rate of about 23-28 cm/year in early infancy (birth to 12 months) and this then decreases to about 7.5 - 13 cm/year in later infancy (1 - 3 years). Many children between the ages of 6 and 18 months move up or down on their growth percentiles, but by 24 months, most children follow their growth curve and stay on the same percentile or growth channel.
In early childhood (3 years to puberty) they will then continue to grow at a rate of about 4.5 to 7 cm/year, up until the time just before they begin puberty, when their growth will slow to about 4 cm/year. Growth then accelerates again as they hit their peak growth velocity in puberty, to about 8-9 cm/year for girls and 10.3 cm/year for boys. Growth then slows again in girls to about 7 cm/year after menarche (the first period) until they reach their adult height. Boys and girls usually continue to grow until they are 14-16 years old, but this depends on when they started puberty.
Among the influences on a child's growth is his overall genetic potential for growth, which can be determined from his parents heights, his nutritional status, and the presence of any chronic medical problems.
Children with short stature are usually below the 3rd or 5th percentile on their growth chart for their height. But just as important as where they are on or below the growth chart is what their growth velocity or rate of growth has been each year.
It is also important to look at a child's weight, in relation to his height. Since overweight or obese children are usually very tall because of an accelerated growth rate, if your child is short and overweight, then he should be evaluated for a medical condition causing his growth problems.
Among the tests that are commonly performed to evaluate the growth of a child with short stature include determining a bone age, which is the chronological age of your child's bones. This is determined by taking an xray, usually of his left wrist and hand. If your child's bone age is much less than his chronological or real age, then there is probably still room for his bones to grow after the age that you would normally expect him to already stop growing. Girls usually continue to grow until a bone age of about 14 years, and boys stop growing after a bone age of 16 years (with a peak growth rate at a bone age of 14 years).
Other tests can include blood tests to check for hypothyroidism (T4 and TSH), growth hormone levels (usually by checking IGF-1 and IGF BP3), complete blood counts (CBC to check for anemia), blood chemistries (which can include a SMA 20 to check for liver and liver disease), urinalysis, and sometimes a karyotype to look for chromosomal abnormalities (especially in girls who may have Turner syndrome).
If the above tests are normal, or if your Pediatrician didn't think that testing was even necessary (which is often the case for many short children), then your child's rate of growth can just be closely followed every 3-6 months, with a further evaluation being performed if he does not continue to have a normal rate of growth.
Since familial and genetic influences strongly determine how a child grows, most children with short parents will have short children. This is termed familial short stature. You can use our height calculator to figure out your child's genetic potential for height based on his parents heights using our Height Calculator. While children with familial short stature may be at or near or just below the 3rd or 5th percentile on their growth chart for their height, their growth curve or channel will run parallel to the normal growth curves and they have a normal rate of growth. They also have a bone age that is close to their chronological age, showing that there is not any extra room or time to grow. Although growing normally, children with familial short stature will usually be short as adults, with a similar height to their parents.
Another normal condition that can cause short stature is a constitutional delay in growth. These children, although short, have a normal growth velocity or rate of growth and will usually have a delay in starting puberty, and possibly a prolonged slowdown in growth that is usually present in children just before they begin puberty. They will usually also have a bone age that is much less than their chronological age, showing that there is room to grow and that they will continue growing even after other children of the same age have stopped growing. Because of the extra room and time to grow, children with constitutional delay usually have a normal adult height. Similarly, other family members usually also report a delay in starting puberty and a late adolescent growth spurt and have a normal final adult height. While children with a constitutional delay in growth will eventually begin puberty, go through the pubertal growth spurt and reach a normal final adult height, it can be distressing for many teens to be so much shorter and less developed than their peers. In this case, he may need referral to a Pediatric Endocrinologist for an evaluation and possible treatment with montly testosterone injections to hasten the start of puberty (although it will eventually start on its own without treatments).
Many parents are worried about growth hormone deficiency in their short children. Growth hormone is required for normal growth, and children with growth hormone deficiency are short, often look younger than their chronological age, and they can be chubby with their weight higher than their height. While they will usually have a delay in their bone age, like children with a constitutional delay, children with growth hormone deficiency will have a slow rate of growth and they will have a growth curve that falls away from the the normal growth curves (unlike other normal causes of short stature which have a normal rate of growth and a growth curve that runs parallel to the growth chart). Testing that can be done if your Pediatrician suspects your child has growth hormone deficiency include checking the levels of IGF-1 and IGF BP3, which will be low. A growth hormone stimulation test may also be done by an endocrinologist.
Treatments for growth hormone deficiency include growth hormone replacement. Other conditions for which growth hormone is currently being successfully used include Turner syndrome, chronic renal failure and Prader-Willi syndrome.
Growth hormone defiency may be congenital (a child is born with it), or it may be acquired later in life from head injury or a brain tumor or mass.
Recently, the indications for which kids can be treated with growth hormone has been expanded. Growth hormone can now be used for the long-term treatment of children with idiopathic (of unknown origin) short stature, also called non-growth hormone deficient short stature, who are more than 2.25 SD below the mean for age and sex, or the shortest 1.2% of children. For example, according to the FDA, for 10-year old boys and girls, this would correspond to heights of less than 4' 1" inch. This would further correspond to heights of less than 5' 3" and 4' 11" in adult men and women, respectively.
Some new studies and reports have recently shown that another group of these short kids, those who were born Small for Gestational Age (SGA), may also benefit from treatment with human growth hormone. The International Small for Gestational Advisory Board has recommended that if 'a short child who was born SGA has not caught up by age 2 to 3 years of age and whose catch-up growth has stopped should be referred to a pediatrician who has expertise in endocrinology.'
Among the factors that will make your Pediatrician suspicious that there is a medical reason for your child's short stature and that a further evaluation is necessary include:
- if your child's plotted height on a growth curve is crossing percentiles downward after 18-24 months of age. For example, if his height had been following along at the 75th percentile and has now moved down to the 10th or 25th percentile.
- poor appetite and/or poor nutrition
- chronic abdominal pain and diarrhea
- persistent fever
- weight loss
- chronic worsening headaches and/or vomiting
- weight gain
- delayed puberty
- a growth curve very much below the 3rd percentile
- a peak growth velocity of less than 6 cm/year during puberty
- a height that is much below that predicted by mid-parental height
- if your child's short stature is disproportionate or he has other dysmorphic signs which can indicate a chromosomal disorder.