Gonadotropin Suppression for 7 Years After a Single Histrelin Implant for Precocious Puberty

Gonadotropin-releasing hormone analogues (GnRHas) are an effective treatment to address the compromise in height potential seen in patients with central precocious puberty. There is no evidence in the literature of a single GnRHa used for longer than 2 years before being removed or replaced. We describe a patient who was on continuous gonadotropin suppression for 7 years and despite this, achieved a height potential within 1 SD of mid-parental height. A boy aged 10 years 3 months presented to the endocrine clinic with signs of precocious puberty and advanced bone age. Initial laboratory values were a random luteinizing hormone (LH) level of 9.4 mIU/mL, follicle-stimulating hormone (FSH) 16.3 mIU/mL, dehydroepiandrosterone sulfate 127 mcg/dL, and testosterone 628 ng/dL. The patient was initially started on Lupron injections before transitioning to a histrelin implant. Follow-up laboratory results 5 months post-suppression showed pre-pubertal random LH 0.2 mIU/mL, FSH 0.1 mIU/mL, and testosterone 5 ng/dL. The patient was lost to follow-up and returned 5 years later presenting with gynecomastia and delayed bone age. He had continuous gonadotropin suppression with random LH 0.10 mIU/mL, FSH 0.16 mIU/mL, and testosterone 8 ng/dL. The histrelin implant was removed, and 4 months later, his random pubertal hormone levels were LH 5.6 mIU/mL, FSH 4.3 mIU/mL, and testosterone 506 ng/dL. The patient's mid-parental height was 175.3 cm and his near final height was 170.6 cm, which is within 1 SD of his genetic potential. Further studies are needed to explore continuous gonadotropin hormone suppression with a single histrelin implant beyond 2 years.