Background: Gender disparities were found in reports of early pediatric recombinant human growth hormone (rhGH) use in the USA. With rhGH entering its third decade, we sought to examine US gender-based treatment patterns and how these patterns compare to that of other countries.

Methods: All children entered in the Pfizer International Growth Study (KIGS), a database designed to document long-term outcomes and safety of Genotropin®, were categorized by gender, location, date and age of therapy initiation, and diagnosis. Measures of national health status, health care expenditure, general economic indices and mean adult heights were also compared.

Results: Throughout the past 30 years, USA had an almost 2:1 male:female ratio overall. The gender ratio depended on the specific indication and age. There was no consistent relation to geographic region, pediatric population size, or density of pediatric endocrinologists. Male predominance was seen in Asia (mostly Japan), USA and Europe/Australia/New Zealand (65%, 64% and 55%, respectively), but not the rest of the world (47%), where rhGH was prescribed less frequently. In the countries with the greatest rhGH use, the gender ratios depended on the specific indications but did not correlate with mean adult height, national healthcare measures or general economic indices.

Conclusions: Male predominance among US pediatric rhGH recipients persists, especially for indications without a clear organic etiology. Global differences in gender ratios suggest factors other than biology are at play. We speculate that social and cultural pressures and the healthcare systems' permissiveness towards paying for rhGH therapy contribute to these international differences.