Triptorelin-stimulated gonadotropin concentrations for precocious puberty

Purpose: Subcutaneous triptorelin stimulation testing is used to evaluate girls with early breast development when intravenous gonadotropin-releasing hormone is unavailable, but the optimal sampling times and minimum test duration remain uncertain.Methods: We retrospectively analyzed 186 girls younger than 8 years who presented with breast development and underwent subcutaneous triptorelin testing (0.1 mg), with serum luteinizing hormone (LH) and follicle-stimulating hormone measured at 0, 30, 60, 90, and 120 minutes. Central precocious puberty (CPP) was defined as peak LH ≥5.0 IU/L; those below this threshold were classified as premature thelarche (PT). We performed receiver operating characteristic analyses for stimulated LH at 30, 60, 90, and 120 minutes and compared LH trajectories using mixed-effects modeling.Results: CPP was identified in 88 girls (47.3%). Using the 5.0 IU/L threshold, cumulative detection reached 90.9% by 60 minutes, 95.5% by 90 minutes, and 100% only by 120 minutes. Peak timing differed between groups: LH peaked mainly at 30–60 minutes in the CPP group (33.0% at 60 minutes; 29.5% at 30 minutes) and at 120 minutes in the PT group (51.0%). Diagnostic discrimination was excellent at all time points (area under the curve, 0.993–0.999), and LH trajectories differed significantly between groups (group-by-time interaction, P<0.001).Conclusion: Although stimulated LH showed excellent discrimination at each sampled time point, sampling through 120 minutes was required to maximize sensitivity and minimize false-negative classification using a peak LH threshold of 5.0 IU/L.