NEW YORK – Significant growth slowdown during treatment with stimulants may occur in a small subset of children who require closer monitoring and referral, Dr. Harold E. Carlson said at a psychopharmacology update sponsored by the American Academy of Child and Adolescent Psychiatry.
“It's pretty well established that children who receive stimulants, typically for [attention-deficit hyperactivity disorder], can have some slowing of their growth,” said Dr. Carlson, head of endocrinology at the State University of New York at Stony Brook.
Height velocity, or yearly growth, typically slows for the first few years of stimulant therapy and then resumes at a nearly normal rate. Pubertal development is normal.
Final adult height is usually normal with long-term use of stimulants. However, a small subset of patients, perhaps 10%, has a more significant slowdown of growth, Dr. Carlson said.
“I don't think anybody has a good handle on how many [children experience this significant slowdown], and we certainly don't have a good idea as to how to identify them ahead of time,” he said.
Because the secretion of growth hormone in these children is normal, researchers have speculated that the slowdown may be related to a decrease in food intake during stimulant use. “That's probably it,” Dr. Carlson suggested, because “people on stimulants, especially on higher doses, often lose their appetite.”
The slowdown of growth is greater in prepubertal children, boys, children who are taller or overweight at baseline, and children who use sustained-release medications.
Little data exist on the final adult height of children who have taken stimulants, Dr. Carlson said. Few studies have extended follow-up beyond 16 years of age for girls and 18 years for boys. In one study, 97 boys aged 4–12 years who were treated with methylphenidate for a mean of 36 months grew to a final adult height at 21–23 years of age that was similar to the final adult height of other males in their family, their community, and unmedicated controls. These data are “reassuring,” Dr. Carlson said, but “we want to emphasize that there may well be a subset of children who do have more significant slowing of growth.”
Dr. Carlson recommended obtaining prior growth records and measuring the height and weight of children before beginning stimulants. Height and weight should be measured and plotted every 6 months during treatment. A decrease of more than one standard deviation in height for age during treatment should prompt consultation to exclude other disorders such as hypothyroidism or gastrointestinal diseases.