How much has she grown since the last visit? What is his height today? These are very likely the most common questions parents ask at their child’s annual checkup. Although we like to say that children grow two to 2 ½ inches a year, the reality is far more complicated.
On average, babies grow 10 inches in the first year and another four inches in the second. The rate of linear growth slows year by year after that until the onset of puberty. Right before puberty, growth may only be two inches per year, but by the middle of puberty height is increasing by as much as four inches each year.
Adult men are on average five inches taller than women, the principle reason being differences in the timing of puberty. The earlier puberty starts, the earlier growth finishes. On average, girls generally finish puberty at about the same time that boys are just beginning.
Whether a child is tall, average or on the short side, a normal rate of growth assures clinicians that everything related to growth is as it should be. A child who has had a slowdown in growth is always a concern no matter what the child’s height may be, and careful monitoring of growth by the pediatrician is important.
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Most short children simply have familial or genetic short stature. By definition, children with familial short stature grow normally, have normal puberty and reach a height that is in keeping with that of the parents. Even when the rate of growth is normal, parents may still worry that the child’s short stature will result in psychological problems. Results of studies are not clear on that. In fact, one very interesting study indicated that children are just as likely to consider their short classmates as good leaders as they are their classmates who are tall.
Children with normal growth and short stature can also catch up. This happens when puberty starts later than usual, and the children continue to grow even after their friends have finished. An X-ray image of the hand can be used to determine the “bone age,” or more precisely the extent of the maturation of the skeletal system. A delayed bone age predicts a potential for greater continued growth. Children with normal growth, short stature and delayed advancement of skeletal age usually turn out to have late puberty and catch up in growth on their own.
When the cause of the slow growth is not clear, tests are needed to exclude problems in general health and in the endocrine system, which is responsible for normal growth. Hormonal problems that present with a slowdown in growth include inadequate production of thyroid hormone and growth hormone deficiency. Hypothyroidism is easily diagnosed with blood tests that measure the amount of thyroid hormone in the blood.
Confirming a diagnosis of growth hormone deficiency requires a slightly more complicated evaluation. Growth hormone levels are rising and falling in the blood stream at different times of the day, so a single blood test may not pick up a level of growth hormone that is high enough to say that growth hormone production is normal. To diagnose growth hormone deficiency, specific medications are given that briefly increase the growth hormone levels in the blood, and several blood samples are obtained to determine if the increase in the growth hormone levels is normal.
Growth hormone therapy is needed when growth hormone production is insufficient for normal growth. Even though the growth hormone used for treatment is identical to the hormone the body makes, side effects can occur, and the decision to treat with growth hormone therapy should only be made when there is a clear indication that the benefits outweigh the potential risks.
Attention has also been paid to the role of growth hormone treatment for children with height that is well below the normal range but for whom no cause can be determined. Growth hormone therapy has been approved for this condition, but the benefits of treatment remain controversial. Studies that have been published indicate an overall benefit of about two inches in height. But the benefits for any individual child are hard to predict, and there is currently no evidence that growth hormone therapy improves the quality of life.
While every child develops differently, markers such as growth rates are good indicators of whether your child is maturing normally. If you are worried about your child’s growth, share your concerns with your pediatrician.
Gary D. Berkovitz, M.D., is a professor pediatrics and Chief of Pediatric Endocrinology at UHealth – University of Miami Health System. For more information, visit UHealthSystem.com/patients/pediatrics.