SAT-127 Predictive Value of Leuprolide-Stimulated Estradiol Levels in Girls With Central Precocious Puberty (CPP)

Abstract T. Colangelo: None. S. Sridhar: None. K. Bangalore Krishna: None. L.R. Garibaldi: None. Background: When random LH and estradiol levels are low or minimally elevated in the context of physical findings and imaging suggestive of puberty, GnRH stimulation testing is performed to assess the activation of the HPG- axis and differentiate central precocious puberty (CPP) from isolated premature thelarche (PT). However, when the stimulated LH values (stLH) do not meet the diagnostic criteria, additional data become important in diagnosing CPP and guide treatment. The aim of this study was to evaluate the diagnostic role of 24-hr leuprolide-stimulated estradiol levels (stE2) compared to baseline and leuprolide stimulated LH concentrations, in the diagnosis of CPP in girls. Methods: The study was a retrospective analysis of girls who underwent a leuprolide stimulation test for evaluation of CPP. A diagnosis of CPP was made based on clinical findings and either a baseline ultrasensitive LH of > 0.4 IU/L (Quest)/a baseline estradiol >50 pg/ml/120 min stLH of 5 IU/L or above. Categorical variables were tested using Pearson’s chi-square test. Pearson correlation was used to assess correlation between variables. The area under the receiver operating characteristic curve (AUC) was used to assess the predictive capacity of the variables. Results: Seventy girls with premature breast development were studied. Of them, 38/70 (∼55%) girls were diagnosed with CPP. Mean age at the onset of thelarche in CPP girls was 7.3 years (SD 1.6). Both baseline and stLH correlated with the stE2 level (r=0.49, 0.54 respectively, p=<0.001). For 40 girls with stLH < 5IU/L, stE2 levels were >=50 pg/ml in 12 girls (30%) and >=40 pg/ml in 17 girls (42%). For 35 girls with stLH<4 IU/L, stE2 was >50 pg/ml in 11 girls (31%) and > 40pg/ml in 15 girls (42%). Of the 27 girls with st LH >5IU/L, 22 were diagnosed with CPP (81%). Of 5 girls with stLH between 4 -4.9 IU/L, 2 were diagnosed with CPP (40%). Of 35 girls with stLH < 4IU/L, 7 were diagnosed with CPP (20%). Of the 31 girls with stE2 >50pg/ml, 23 were diagnosed with CPP (74%) and of the 4 girls with stE2 between 40 -49pg/ml, 2 were diagnosed with CPP (50%). Binary logistic regression with baseline LH and stE2 with stLH at 120 min as the independent variable showed an AUC of 0.841 and 0.851 respectively. ROC-curve analysis showed for an LH level >3.09 IU/L, a sensitivity of 81.5% and <25% false positive rate and for a stE2 level >47pg/ml, a sensitivity of 81.5% and <30% false positive rate in predicting CPP. AUC value for stLH at 120 min was 0.83 and stE2 was 0.81 suggesting diagnostic accuracy for CPP. Conclusion: To confirm/exclude CPP based on clinical characteristics, it is important to evaluate the activation of the HPG axis to reliably distinguish it from PT. This study showed that the stE2 level is in the pubertal range in at least 30% the girls who would be classified as PT based on the stimulated LH cut-off values of 4-5, or <4 IU/L, making it a useful adjunctive measurement to establish or support a diagnosis of CPP. Saturday, June 1, 2024