Resumption of Puberty in Girls and Boys Following Removal of the Histrelin Implant

ObjectivesTo determine time to menarche in girls and testicular volume increase in boys after removal of a histrelin implant, which causes profound hypothalamic-pituitary-gonadal axis suppression.Study designMedical records of patients treated with a histrelin implant were reviewed. Seventy-one patients (56 girls) treated with the histrelin implant were identified, of these patients, 37 explanted girls (68% naïve) and 6 explanted boys (83% naïve) were included in the analysis. Time to menarche after explantation in girls and time to testicular volume increase after explantation in boys were determined. Additional variables investigated included indication for and duration of treatment, history of menarche (girls), previous therapy, and age at beginning and end of histrelin treatment.ResultsOf the girls, 30 were treated for central precocious puberty (CPP), 26 had menarche at an average of 12.75 months after explantation. Of the 30, 7 were treated for other indications, of whom 6 had reached menarche. In girls with CPP, older age at explantation correlated with sooner menarche (P = .04). All boys achieved spontaneous testicular enlargement within 1 year of explantation.ConclusionsThis study documented resumption of puberty after histrelin explantation in treatment naïve and non-naïve boys and girls with and without CPP. Menarche in girls with CPP occurs within a similar timeframe to that observed after other treatment approaches.