Growth Hormone Stimulation Testing Patterns Contribute to Sex Differences in Pediatric Growth Hormone Treatment

Abstract

Introduction: Males are twice as likely as females to receive pediatric growth hormone (GH) treatment in the USA, despite similar distributions of height z (HtZ)-scores in both sexes. Male predominance in evaluation and subspecialty referral for short stature contributes to this observation. This study investigates whether sex differences in GH stimulation testing and subsequent GH prescription further contribute to male predominance in GH treatment. Methods: Retrospective chart review was conducted of all individuals, aged 2–16 years, evaluated for short stature or poor growth at a single large tertiary referral center between 2012 and 2019. Multiple logistic regression models were constructed to analyze sex differences. Results: Of 10,125 children referred for evaluation, a smaller proportion were female (35%). More males (13.1%) than females (10.6%) underwent GH stimulation testing (p < 0.001) and did so at heights closer to average (median HtZ-score −2.2 [interquartile range, IQR −2.6, −1.8] vs. −2.5 [IQR −3.0, −2.0], respectively; p < 0.001). The proportion of GH prescriptions by sex was similar by stimulated peak GH level. Predictor variables in regression modeling differed by sex: commercial insurance predicted GH stimulation testing and GH prescription for males only, whereas lower HtZ-score predicted GH prescription for females only. Conclusions: Sex differences in rates of GH stimulation testing but not subsequent GH prescription based on response to GH stimulation testing seem to contribute to male predominance in pediatric GH treatment. That HtZ-score predicted GH prescription in females but not males raises questions about the extent to which sex bias – from children, parents, and/or physicians – as opposed to objective growth data, influence medical decision-making in the evaluation and treatment of short stature.