Growth Hormone Helps Short Children Achieve Normal Adult Height

Peggy Peck

October 13, 2004

Oct. 13, 2004 (San Francisco) -- About one in 100 children meet the definition for idiopathic short stature (ISS), but not all of them are good candidates for growth hormone therapy, according to pediatric endocrinologist Ron Rosenfeld, MD, senior vice president for medical affairs at the Lucile Packard Foundation for Children's Health at Stanford University in California.

Dr. Rosenfeld discussed ISS and other indications for growth hormone therapy at the American Academy of Pediatrics (AAP) 2004 National Conference & Exhibition.

In July 2003, the U.S. Food and Drug Administration (FDA) approved somatropin (Humatrope; Eli Lilly Co.) for the treatment of ISS, which is defined by the American Association of Clinical Endocrinologists and the Growth Hormone Research Society as height more than two standard deviations (SD) below the mean for age and sex. This definition describes more than 2% of children. Dr. Rosenfeld said the FDA uses a narrower definition of -2.25 SD below the mean for age and sex, which represents "the smallest child out of one hundred." This corresponds to adult heights of less than 5'3" for men and less than 4'11" for women.

Before the FDA action last year, growth hormone was approved to treat growth hormone deficiency as well as growth deficiency associated with Turner syndrome, chronic renal failure, and Prader-Willi syndrome. Adding ISS to the list of previously approved indications more than doubles the potential market for the treatment, Dr. Rosenfeld said. "Nobody expects that all short children should be treated with growth hormone," he told Medscape. "There are enormous medical, ethical, and financial issues associated with this treatment."

For example, "Short stature is not a disease and nobody has rigorously demonstrated that short kids as a group suffer any particular psychosocial difficulties." Because treatment can cost as much as $20,000 a year and continues until the growth plates fuse, it is not unusual for total treatment costs to be more than $100,000, Dr. Rosenfeld said.

Moreover, while he agreed that recombinant growth hormone treatment "has been very safe thus far, every drug has the potential for adverse side effects." Dr. Rosenfeld explained that he had firsthand experience with this potential. He noted that growth hormone treatment originally used hormones taken from cadaver pituitary glands. The human cadaver product was taken off the market when it was discovered that the contaminated human growth hormone was associated with Creutzfeldt-Jakob disease. "The first patient diagnosed with Creutzfeldt-Jakob was a patient of mine," said Dr. Rosenfeld.

Beyond the concern for safety and the cost of treatment, Dr. Rosenfeld said it is also important to evaluate the reason families seek treatment. "My responsibility is to try to get the child into the broad normal range of height. I am not in the business of making tall people."

But several studies suggest that height is associated with success, Dr. Rosenfeld said. For example, studies from Stanford University and from Carnegie Mellon both found that men with a height from 5'11" to 6'4" earned more than men who were shorter -- or who were taller than 6'4".

"And since this country was founded, the taller candidate in a presidential election was the winner in more than 80% of the elections," Dr. Rosenfeld said. Thus, he said that some families may seek treatment as a way to give a child a competitive advantage. He noted that a physician colleague called to "ask if his 16-year-old, 5'11" son could receive growth hormone treatment to improve his rebounding ability in basketball."

That said, Dr. Rosenfeld added that many ISS children "are just as short as growth hormone-deficient children," which makes them good candidates for treatment.

"Size is always a concern for families," said Myles B. Abbott, MD, chair of the AAP scientific program committee. "As pediatricians, we are regularly confronted by parents who are worried about their children's height." Both pediatricians and parents are "just now becoming aware of the fact that the FDA has approved growth hormone for ISS. I think this may affect the willingness of pediatricians to refer patients for an endocrine evaluation," he said.

Treatment should be considered when a child "falls off the growth chart and shows no signs of climbing back on," Dr. Rosenfeld said. While growth hormone-deficient children are often diagnosed during infancy, ISS children are more likely to be diagnosed later, often during the early primary school years.

"Growth hormone therapy is a race against the clock, since it is only effective until the time that the growth plates fuse. If treatment is initiated at age five, it is likely to last five to eight years," Dr. Rosenfeld said.

AAP 2004 National Conference & Exhibition: Presentation P106. Presented Oct. 9, 2004.

Reviewed by Gary D. Vogin, MD

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