ESPE Abstracts

Background: Organic lesions are present in 5-10% of cases with CPP. Determinants of an increased risk for organic pathology underlying CPP in girls are debatable. CNS imaging is recommended for girls who have pubertal signs before 6 years of age. Although neurological findings may suggest organic pathology, other clinical features and hormonal variables have not been adequately examined.

Aim: To analyze clinical&hormonal characteristics that would point to an organic pathology, thus requirement of CNS imaging in girls with CPP.

Methods: Medical records of 286 girls who had GnRHa therapy for CPP were evaluated retrospectively. All cases had CNS imaging either cranial or pituitary MRI. Chronological age, bone age, height, pubertal stage, gonadotropin and serum estradiol levels, peak stimulated LH level as well as findings of CNS imaging at time of diagnosis were evaluated. Cases with CNS pathology on MRI were classified as organic CPP. Parameters that differentiate organic from idiopathic CPP(iCPP) were determined using ROC curves.

Results: Organic CPP was detected in 6.3%(18/286) of cases. Girls with organic CPP were diagnosed at an earlier age, bone ages were more advanced, bone age-corrected height-SDSs were lower and sex steroid levels and peak stimulated LH levels were higher than girls with iCPP. Puberty started before 6 years of age in 88.9%(16/18) of girls with organic CPP. Mean basal estradiol and peak LH levels of patients with organic CPP at any pubertal stage were similar to those of iCPP at advanced pubertal stages such as Tanner 4(for estradiol 65.2±22.4vs 64.6±21.2pg/ml, for peak stimulated LH 16.6±5.8vs17.2±3.6 IU/L,respectively). Basal estradiol and peak stimulated LH levels were higher in organic CPP than idiopathic cases with matched pubertal stages. Threshold values to distinguish organic and iCPP at Tanner stages 2&3 were 38.1pg/ml for basal estradiol (100%sensitivity,80.4%specifity), and 13.6IU/L for peak LH (100%sensitivity,66.4%specifity).

Conclusion: Pubertal symptoms and signs generally begin before 6 years of age in organic CPP in girls.Hormone levels are much higher than expected according to stage of puberty. CNS imaging is suggested for girls younger than 6 years of age since risk of detecting an organic pathology is higher in this age group. High levels of gonadotropins and sex steroids discordant with stage of puberty may be another indication for imaging regardless of age. CNS imaging should be prioritized in those with an estradiol above 35pg/ml and/or a peak LH above 10IU/L in early stages of puberty(T2&3).