ESPE Abstracts

Background: Boys with delayed puberty represent one of the main cause for pediatric endocrine referrals. Although the majority of them have constitutional delay of growth and puberty (CDGP), it is important to identify isolated hypogonadotropic hypogonadism (IHH) for optimal management.

Objective and hypotheses: The aim of the study was to evaluate the usefulness of inhibin B and AMH as biological markers for distinguishing between CDGP and IHH.

Method: Observational, retrospective and monocentric study. Inclusion criteria included age older than 14 years and Tanner stage I or II.

Results: Forty-five patients with delayed puberty were included, 30 patients with CDGP and 15 with IHH. Compared with CDGP patients those with IHH had lower inhibin B levels (76±75 pg/ml vs 127±63 pg/ml, P=0.016), especially those with Tanner stage I (40±45 pg/ml vs 100±39 pg/ml, P=0.005). In CDGP and IHH patients, sensitivity was 53%, specificity 90% and positive predictive value (PPV) 73% for inhibin concentration of 60 pg/ml or less. In patients with Tanner stage I, sensitivity was 70%, specificity 100% and PPV 100% for inhibin concentration of 41 pg/ml or less. Basal LH concentrations and LH response to LH-RH were significantly lower in IHH vs CDGP (0.64±0.70 UI/L vs 1.20±1 UI/L, P=0.028 and 8.2±8.8 UI/l vs 13.9±6.9 UI/L, P=0.026 respectively). There were no significant differences for AMH, testosterone or FSH levels.

Conclusion: Inhibin B marker is confirmed as the best diagnostic tool to discriminate IHH from CDP in early adolescence. This new study updates the cut-off to 60 pg/ml when using new specific inhibin B reagents (from Anshlabs).