Boys are twice as likely as girls in the U.S. and Asia (mostly Japan) to receive recombinant human growth hormone (rhGH) for growth hormone deficiency, illnesses that affect height, and short stature of a non-medical nature.
A smaller gender difference exists in Europe, Australia and New Zealand, but in the rest of the world short boys and girls are treated at the same rate. This indicates a likely cultural bias for male height in some countries.
The study, by researchers from The Children’s Hospital of Philadelphia and Pfizer, is electronically available prior to publication in the Journal of Clinical Endocrinology and Metabolism.
All children entered in the Pfizer International Growth Study (KIGS), a database designed to document long-term outcomes and safety of Genotropin, one of the three leading commercial brands of rhGH, were categorized by gender, location, date and age of therapy initiation, and diagnosis.
Measures of national health status, health care expenditures, general economic indices and mean adult heights were also compared. Children were categorized into four geographic regions including the U.S., Europe/Australia/New Zealand, Asia and the “Rest of the World.”
Recombinant human growth hormone has been available since 1985. “Because reports found more U.S. males receiving rhGH in its first years of availability, and rhGH use has increased considerably over the past 20 years, we thought it was important to get an up-dated look at the gender-based patterns of use in the U.S. and how they compared to other countries,” said Adda Grimberg, M.D., lead author of the study and a pediatric endocrinologist at The Children’s Hospital of Philadelphia. “We suspect that social and cultural pressures, combined with financial constraints, contribute to the international differences in the gender distributions of children treated with rhGH.”
Historical trends revealed a consistent overall male predominance among U.S. pediatric rhGH recipients at a nearly two-to-one ratio. The gender ratio did not change significantly across the more than 20 years of rhGH use. Males outnumbered females at all ages, especially during the second decade of life. Because boys typically start puberty later than girls and hit their growth spurt at a later stage of puberty, boys who lag behind their peers are more likely to be perceived as having a growth problem.
The factor that most consistently affected the gender distribution was the diagnostic indication for rhGH therapy. The greatest gender disparities occurred for diagnoses without an identifiable cause, such as idiopathic short stature and idiopathic GH deficiency because of the complexity of the diagnostic tests. Prader-Willi syndrome, a genetic disease with multiple benefits from rhGH therapy besides height, was the only indication with gender equality in the U.S. Dr. Grimberg hypothesized, “when the decision to treat involves an indication that relies more heavily on clinical judgment, treatment patterns are more likely to highlight underlying differences in social pressures for tallness.”