Question: My 15-year-old son hasn’t grown much, if at all, for about a year, including his foot size. Has he stopped growing? Or might he still have another growth spurt? I know that boys often grow until they are 21.
Answer: Many factors determine a child’s pattern of growth and final adult height: genes, diet and hormones, among others.
Pediatricians often predict that a child’s final height will be roughly halfway between his mother and father’s — the genetic factor. Until a child grows at least to that level, more growth can usually be expected, unless some other condition has occurred.
Nutrition is the major environmental influence on growth. In countries where women are malnourished during pregnancy, babies are born smaller and are likely to be shorter as adults.
Girls in poor rural areas of India and Africa who suffer from severe malnutrition often do not have their first period until they are in their late teens, since they are not able to eat the minimum amount of fat needed for puberty to begin.
Under normal circumstances, estrogen levels increase in girls with puberty. Estrogen is necessary for girls’ bones to absorb calcium and grow. Girls who are malnourished because of anorexia nervosa may also fail to achieve their full expected height, especially if they become ill with this disease before puberty. Malnutrition delays puberty and interferes with growth.
In boys, blood levels of testosterone and the other related male hormones increase as puberty proceeds. Once those hormones reach a certain level, they actually turn off bone growth.
When a boy has all the physical signs of sexual maturation — for example, the need to shave — he’s likely to have completed his major growth spurt and may only grow another inch or so. The onset of puberty, which varies from child to child, will help predict the timing of growth spurts. On average, girls start those spurts before boys, and often tower over them until the boys catch up.
Since hormones are such a critical part of guiding growth for boys and girls, failure to grow as expected can be a sign of a hormone problem that needs attention.
You didn’t tell us how tall your son is. Without knowing his height or that of his parents, it is impossible tell whether some interference with his growth needs attention. We recommend you share your question with his pediatrician. The pediatrician will check his height and weight, compare it to his overall pattern of growth during childhood by looking at his growth curve, and calculate the midway point between the heights of his biological parents.
The pediatrician will also perform a physical examination to determine his stage of puberty. If, based on this information, his height isn’t as expected, the pediatrician may look further.An X-ray of the wrist bones gives the “bone age” — information about how much more bone growth might be anticipated. Sometimes blood tests are called for, to measure hormone levels.
If these markers aren’t where they should be, further studies may be done to take a closer look at the different organs involved in producing and balancing the different hormones — the hypothalamus and the pituitary in the brain; the adrenal glands that sit atop the kidneys; and ovaries in girls, testes in boys.
Questions or comments should be addressed to Dr. T. Berry Brazelton and Dr. Joshua Sparrow, care of The New York Times Syndicate, 620 Eighth Ave., 5th Floor, New York, N.Y. 10018. Questions may also be sent by e-mail to: nytsyn-families(at)nytimes.com. The (at) represents the symbol on your keyboard. Questions of general interest will be answered in this column, which may be posted on a Families Today Web site or collected in book form. Drs. Brazelton and Sparrow regret that unpublished letters cannot be answered individually.
Responses to questions are not intended to constitute or to take the place of medical or psychiatric evaluation, diagnosis or treatment. If you have a question about your child’s health or well-being, consult your child’s health-care provider.
Dr. Brazelton heads the Brazelton Touchpoints Project, which promotes and supports community initiatives that are collaborative, strength-based, prevention-focused sources of support for families raising children in our increasingly stressful world. Dr. Sparrow, a child psychiatrist, is director of Special Initiatives at the Brazelton Touchpoints Center. Learn more about the Center at www.touchpoints.org.
