IntroductionThere are several concerns associated with gonadotropin-releasing hormone agonist (GnRHa) treatment for central precocious puberty (CPP), such as obesity and changes in body mass index (BMI). We aimed to investigate whether any anthropometric differences exist and if they persist over time.MethodsWe conducted an observational study of Portuguese children (both sexes) diagnosed with CPP between January 2000 and December 2017, using a digital platform, in order to analyze the influence of GnRHa treatment on BMI-SD score (BMI-SDS).ResultsOf the 241 patients diagnosed with CPP, we assessed 92 patients (8% boys) in this study. At baseline, 39% of the patients were overweight. BMI-SDS increased with treatment for girls but then diminished 1 year after stopping GnRHa therapy (p = 0.018). BMI-SDS variation at the end of treatment was negatively correlated with BMI-SDS at baseline (p < 0.001). Boys grew taller and faster during treatment than did girls (p < 0.001), and therefore, their BMI-SDS trajectory might be different.ConclusionsThis study showed an increase of body weight gain during GnRHa treatment only in girls, which reversed just 1 year after stopping treatment. The overall gain in BMI-SDS with treatment is associated with baseline BMI-SDS.

Objective Idiopathic central precocious puberty (iCPP) is common in paediatric endocrinology. Gonadotropin‐releasing hormone agonists (GnRHa) are safe, but the effect on final height and the ideal timing for treatment remains controversial. This study aims to assess the effectiveness of GnRHa on growth outcomes in girls with iCPP treated before and after the age of 8 years old. Design and Patients This retrospective longitudinal study evaluated data from Portuguese girls with iCPP who completed treatment between 2010 and 2021. Measurements Auxological and clinical characteristics were compared according to age at treatment onset. Results A cohort of 134 girls with iCPP, was divided into early treatment (ET) (<8 years, n = 48) and later treatment (LT) groups (≥8 years, n = 86). In both groups, most children presented with Tanner II and III. Tanner IV was more frequent in LT group (p = .003). At the end of treatment, predicted adult height increased in both groups (ET p = .032; LT p = .04) and bone age significantly slowed down in all participants (p = .008, p = .034). The height gain was greater in the ET group, but without significant differences (p = .065). Conclusions Treatment with GnRHa improved final height in all girls with iCPP, even when initiated after 8 years. To achieve better outcomes, treatment should be provided promptly after diagnosis.