ESPE Abstracts

Introduction: in females with precocious thelarche (PT) (< 8 years), elevation of morning luteinizing hormone levels (mLH) may be indicative of pubertal activation of the pituitary gonadal axis. However, this approach could not be satisfactory in real life management of PT due to the risk of reduced specificity and sensitivity of the mLH thresholds. We propose a diagnostic flow-chart based on basal and stimulated gonadotrophins integrated with bone age and ultrasound uterine diameters to screen CPP in females.

Patients and Methods: the clinical, radiologic and hormonal data of 213 consecutive girls with PT who underwent GnRH stimulation test (GnRHST) to exclude CPP were retrospectively evaluated from 2017 to 2020 at our Centre. Bone age was assessed by Greulich-Pyle method, uterine diameters by B-mode ultrasound scans. CPP was diagnosed by LH peak ≥ 5UI/l after GnRHST. Retrospectively a diagnostic flow-chart was created evaluating mLH against the stimulated LH peak, bone age, basal FSH, FSH/LH ratio, longitudinal uterine diameter and uterine volume.

Results: according to the statistical analysis (ROC curves, Younden index) the following features and thresholds were found associated to CPP: mLH ≥0.5 UI/l, FSH ≥3.5 UI/l, mLH/mFSH ≥0.16 UI/l, uterine volume ≥ 3.6 cc, longitudinal uterine diameter ≥41 mm, bone age advancement >1.8 years. According to mLH we subdivided the patients (Pts) in 2 groups: group 1 (≥0.5UI/L) group 2 (<0.5 UI/L), however we found respectively 19% of false positive in group 1 and 17 % of false negative in group 2. Therefore we subdivided the pts more accurately in 3 groups according to mLH: group A, 31 pts: ≥ 1,5 UI/L; group B, 36 pts: 0.5-1.4 UI/L; group C,146 pts: <0.5 UI/L: CPP was found in 100% of pts of Group A, 34% of group B and 17% of group C. In Group C, 41 pts (28%) without any of the clinical features reported above did not show CPP, in the remaining 105 pts with at least one feature 25/105 pts has CPP.

Conclusion: our data seem to confirm the correlation between mLH and LH peak. GnRHST seems not necessary to diagnose or exclude CPP in cases with mLH levels ≥1.5 IU/l and in cases with <0.5 UI/l without any puberty-associated clinical features. In the other pts with low levels of mLH a careful evaluation of other basal hormonal levels and other positive predictive features should advice the GnRHST evaluation case by case.