Testosterone priming increased growth hormone peak levels in the stimulation test and suppressed gonadotropin secretion in three Japanese adolescent boys

[Introduction] The guidelines from the Pediatric Endocrine Society in 2016 recommended sex steroid priming before GH stimulation test in prepubescent boys older than 11 yr to avoid false positives owing to physiological hyposecretion of GH. While a previous study showed an elevation in peak GH levels in the stimulation test after testosterone priming, there have been no such reports from Asian countries, including Japan. Although the secretion of gonadotropins would be suppressed by the negative feedback of testosterone priming, gonadotropin levels associated with testosterone priming have not been evaluated in the guidelines. Here, we aimed to determine whether testosterone priming would increase peak GH levels in Japanese boys and assess the effect of testosterone priming on gonadotropin secretion. [Materials and Methods] After receiving approval from the Institutional Review Board at Keio University School of Medicine (institutional review board number 20150104) and providing opt-out statements, we retrospectively reviewed medical records of all male patients who underwent GH stimulation tests between 2017 and 2019 in the Department of Pediatrics, Keio University Hospital.