ESPE Abstracts

Introduction: Central precocious puberty is characterized by early activation of pituitary-gonadal axis, often associated with high levels of insulin-like growth factor-I (IGF-I), together with accelerated growth and bone maturation, which can ultimately lead to a low adult height (HT). Treatment with GnRH-agonists (GnRHa) can help reducing growth acceleration and rate of bone maturation, though not always restoring prepubertal growth velocity. The causes of different growth response during GnRHa treatment have not been elucidated yet. To date, several studies have examined the effect of GnRHa on IGF-I and growth velocity (GV) with conflicting results, and the role of IGF-I in growth during CPP-treatment is still debated.

Aims: The present study investigated the possible role of IGF-I as predictor of growth velocity reduction during GnRHa treatment

Methods: Data from 50 girls younger than 9 years old diagnosed with precocious and early puberty (Tanner stage B2 and LH peak response to GnRH test above 5 mU/L) and treated with GnRHa for at least 12 months were retrieved from medical records. Their auxological parameters, serum IGF-I and bone age were collected at diagnosis and during treatment.

Results: At diagnosis, median age was 7.8 years (IQR 7.5-8.2), whereas mean HT-SDS was 0.35± 1.06 SDS and mean BMI-SDS 0.69±1.18 SDS. Median estradiol was 8.0 pg/mL (IQR 5-23), median basal LH was 0.5 mU/L (IQR 0.3-1.5) and LH peak 12.1 mU/L (IQR 7.6-22.4). Mean baseline IGF-I SDS was 1.68±1.42 SDS (>2 SDS in 22/50 patients, 44%). At baseline, IGF-I SDS resulted positively correlated to Tanner stage (P = 0.025), BMI-SDS (P = 0.011), LH peak (P =0.031) and DHEAS-SDS (P = 0.004). After 12 months of treatment, IGF-I SDS significantly decreased (P =0.021) (>2 SDS in 15% patients), whereas HT-SDS did not significantly further increase. Basal IGF-I SDS showed a positive correlation with GV-SDS at 12 months (P =0.003, R² 0.201) which, remarkably, resulted independent from chronological age at diagnosis.

Conclusions: Present results confirm the importance of pretreatment IGF-I in supporting CPP diagnosis, and firstly highlight its predictive role in growth velocity reduction during GnRHa treatment. Noteworthy, chronological age at diagnosis did not represent an important determinant for the growth response to therapy.