ESPE Abstracts

Background: The GnRH stimulation test is widely used in the evaluation of precocious puberty but it requires repeated blood sampling, time-consuming and uncomfortable for the patients.

Objective and hypotheses: To identify which parameters can be used to predict pubertal response in GnRH stimulating test for the diagnosis of central precocious puberty (CPP) in girls.

Method: Included in the study 123 girls aged 3–9 years that underwent GnRH stimulating test due to early pubertal development. Clinical parameters were collected from the medical files. The results of GnRH tests were retrieved retrospectively. Stepwise logistic regression was used to identify which variables can predict the probability for GnRH pubertal response (peak LH ≥6 IU/l).

Results: Included in the final model the following variables; age, Tanner breast stage (B1–5) and basal LH with cut of point of LH >0.3 IU/l (P< 0.0001, C-statistic 84.3%). In girls aged 3–6 years that presented with Tanner B2 and in girls aged 7–9 years that presented with Tanner B1, when basal LH was ≤0.3 IU/l, the predictive probability for pubertal response in GnRH test was <9%. In girls aged 3–9 years that presented with Tanner B3 and with basal LH higher than 0.3 IU/l, the probability for pubertal response was more than 72%. BMI and advanced bone age were not significantly associated with GnRH pubertal response.

Conclusion: Basal LH combined with age and Tanner breast stage can predict the response to GnRH test, therefore GnRH test is unnecessary in the majority of the cases for the diagnosis of CPP in girls.