Parents and children, especially tweens and teenagers, often worry when they notice that they are shorter than many of their peers and classmates of the same age.
While there are many medical conditions that can cause children to have short stature, most children who are short are normal.
This is one time when kids can blame their parents, or at least their genes, for something. Most children are short because they have short parents. Genetics plays a very big role in how tall a person will be.
Parents often ask if their doctor can figure out how tall their children will be. While your pediatrician doesn't have a crystal ball to see how tall your children will be when they grow up, there is a simple formula that uses parental heights to help them estimate a child's target height or their genetic potential for growth. In general, you average the birth parent's heights together and then add 2 1/2 inches if the child is a boy, or subtract 2 1/2 inches for a girl. You can also use an online height predictor to make the calculations for you.
Figuring out a child's target height is important, because if a child is far below his genetic potential, then that may be a sign of a problem.
Children grow rapidly in the first 4 years of life (particularly in the first 2 years), at rates as high as 4 inches per year on average. After age 4, children usually grow at a steadily decreasing rate that goes as low as 2 to 2 1/2 inches per year - up until they begin puberty. Then as they hit their peak growth spurt in puberty, girls grow about 3 to 3 1/2 inches per year, and boys grow about 4 inches per year. After teens hit their peak growth spurt, their growth will slow steadily until they reach their full adult height, about 4-5 years after their peak growth spurt.
Boys and girls usually continue to grow until they are 14 to 16 years old, but this depends on when they started puberty, which can begin anywhere between 8 and 13 for girls and 9 and 14 for boys. For example, if a girl starts puberty at age eight, then she might hit her growth spurt at age nine and be done growing by the time she is 13 years old. On the other hand, if another girl doesn't start puberty until she is 12 years old, then she might continue growing until she is 17 years old.
Also remember that girls reach their pubertal growth spurt about two years earlier than boys, so in early adolescence, many girls are taller than boys.
In addition to the height of their parents, these differences in the timing of the start of puberty accounts for a lot of the differences in the heights of children in the tween and early teen years.
Evaluating The Short Child
When evaluating short children, more important than where they are on a growth chart is how they have been growing. To look at this pattern of growth, or a child's height velocity, you usually have to look at several years of growth.
Children who are growing normally should follow their growth curve fairly closely, so even if they are at the 5th or 3rd percentile, if that is where they have always been then they are probably growing normally. If your child is crossing percentiles or lines on the growth curve, then there may be a medical problem causing him to be short. Keep in mind that children may normally cross percentiles in the first few years of life, and this is actually a common finding in children with short parents or a constitutional growth delay (sometimes called "late bloomers").
Other red flags that may indicate a growth problem include having a chronic medical condition or other chronic symptoms, such as vomiting, diarrhea, fever, weight loss, poor appetite, poor nutrition, headaches, and delayed puberty. Having disproportionate short stature can be a sign of a chromosomal disorder, such as achondroplastic dwarfism, and being both short and overweight can indicate an endocrine or hormonal problem.
The most important part of evaluating a child with short stature is reviewing their growth records or growth chart. If a short child has had more than one pediatrician, then it is a good idea to get all of the child's old records together for their current pediatrician to review. If they are simply short but growing normally, then no further testing may be required. Your doctor may decide to just observe your child's growth over the next 3 to 6 months to make sure that he continues to grow normally.
Testing Short Children
Testing short children is sometimes required, though, either to rule out a medical condition that may be causing short stature or to reassure a short child or a parent that he is growing normally.
One of the most important tests is a bone age. To determine your child's bone age, your doctor will order an xray of your child's hand. The xray is compared to a series of standard hand xrays from normal children of different ages. For instance, if your child's hand xray looks most like the standard 8 year old xray then your child is said to have a bone age of 8 years old.
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). Having a delayed or advanced bone age can also be a sign of a problem that needs further evaluation.
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 (to check for anemia), blood chemistries (which can include a SMA 20 to check for kidney and liver disease), urinalysis, and sometimes a karyotype to look for chromosomal abnormalities (especially in girls who are suspected of having Turner syndrome).
Some Causes of Short Stature
One of the most common normal reasons for your child to be short is having familial short stature, which means a child's parents and other family members are also short. These children usually grow at a normal rate, although they are short, and they follow a growth curve that may be below but parallel to the normal growth curves. Testing is not routinely required, but if a bone age is done, the result would be normal and not delayed.
Another common cause of short stature in normal children is having a constitutional delay of growth. Children that have this normal variation of growth are short and are growing at or below the 3rd percentile for their height. Their rate of growth will be normal at 2 to 2 1/2 inches per year. These children will have a delayed bone age, showing that there is still extra room to grow. They also often have a delay in beginning puberty. Although short, children with constitutional growth delays will commonly continue to grow when other children have stopped growing and they should reach a final adult height that is near their target height. These children are sometimes described as being "late bloomers", and there are usually other family members that also developed late and followed this pattern of growth.
Treatments for Short Children
Although there are a lot of normal reasons for your child to be short, there are also some serious conditions that require treatment. Children with these conditions are short, but are also not growing normally, are not following a growth curve, and often cross percentiles downward.
One of these conditions, and the one that parents are usually worried about, is growth hormone deficiency. Growth hormone is required for normal growth, and children with growth hormone deficiency are short, often look younger than their chronological age, and can be overweight. 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. Growth hormone deficiency 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.
if your pediatrician suspects your child has growth hormone deficiency, he can check your child's levels of IGF-1 and IGF BP3, which will be low in a child with a deficiency. A growth hormone stimulation test may also be done by a pediatric 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 therapy has also recently been approved for the long-term treatment of children with idiopathic short stature, also called non-growth hormone deficient short stature, if they are more than 2.25 standard deviations below the mean for age and sex, or among the shortest 1.2 percent of children.
It is important to note that growth hormone shots are expensive, are usually given to short children for six out of seven days of the week until they complete puberty, and will usually only get a child an extra 2 to 3 inches of growth. So a short child who has a predicted height of 5'6", and who has idiopathic short stature, likely won't become 6 feet tall just because he is getting growth hormone shots.
Growth hormone can also be used for children who were born small for gestational age and do not catch up in their growth by the time they are two years old.
Keeping good records of your child's height and weight can make it a lot easier to evaluate a child with short stature. Be sure to go to your regular well child visits with your pediatrician, and even at a sick visit, ask them to measure your child's height if it hasn't been done recently. While most pediatricians can begin the initial evaluation of a short child, if additional testing is required, or you or your child need reassurance, then a visit to a pediatric endocrinologist can be helpful.
American College of Medical Genetics (ACMG) practice guideline: Genetic evaluation of short stature. Genetics in Medicine: June 2009 - Volume 11 - Issue 6 - pp 465-470.
Gubitosi-Klug RA. Idiopathic short stature. Endocrinol Metab Clin North Am, September 2005; 34(3): 565-80.
Kronenberg: Williams Textbook of Endocrinology, 11th ed.
Leschek EW. Effect of growth hormone treatment on adult height in peripubertal children with idiopathic short stature: a randomized, double-blind, placebo-controlled trial. J Clin Endocrinol Metab, July 2004; 89(7): 3140-8
Quigley CA. Growth hormone treatment of non-growth hormone-deficient growth disorders. Endocrinol Metab Clin North Am, March 2007; 36(1): 131-86