Growth hormone therapy can help some shorter-than-normal children reach their genetic height potential, but much depends on how early treatment is begun, according to a new study.

Using information from a large international database of children treated with growth hormone, researchers found that the therapy was able to help many reach or come close to their genetic height potential - as determined by the combination of both parents’ heights.

Still, the children typically achieved a height that was in the lower end of the normal range for their age, making the overall results “somewhat disappointing,” the study authors report in the Journal of Clinical Endocrinology & Metabolism.

Starting treatment at an early age seemed to be one key to success, as the amount of growth before puberty was related to final height, according to the researchers, led by Dr. Edward O. Reiter of the Baystate Children’s Hospital in Springfield, Massachusetts.

Synthetic growth hormone has long been used to treat children who are shorter than normal due to deficiency in the hormone. Most studies have found that while the therapy helps, children typically fail to reach their full genetic height potential.

In recent years, though, there has been a trend toward starting growth hormone therapy at a younger age, according to Reiter and his colleagues. To see whether this trend might be making a difference in children’s final height, the researchers analyzed a large database that drugmaker Pfizer maintains on patients using its growth hormone product.

The database provided “near-adult” heights for 1,258 children from Europe, Japan, the U.S. and elsewhere who had been treated for growth hormone deficiency. Males older than 17, females older than 15, and all teens who were growing at a rate of less than 2 centimeters per year were considered to have reached near-adult height.

Overall, the study found, the children typically reached a height that was close to what would be expected based on their parents’ heights, though they often remained short for their age.

Children who had greater growth before puberty or who showed a strong response to therapy in the first year tended to reach a greater final height.

These findings, according to Reiter’s team, suggest that “early and aggressive diagnosis and treatment” of growth hormone deficiency is the best way to help children reach their full height potential.

Reiter and his colleagues have served as advisors to the company, and one study author is a Pfizer employee.

SOURCE: Journal of Clinical Endocrinology & Metabolism, June 2006.