Endocrine Abstracts

Background: Growth hormone deficiency (GHD) is the most frequent endocrinological disorder inchildren with short stature, but there are significant controversies in the diagnosis due to lack of reliablediagnostic criteria. Moreover, at final height (FH) attainment, many subjects diagnosed withisolated GHD re-test normal. It is not clear whether this represents a form of transient GHD or a false positive diagnosis during childhood.

Aim: To evaluate differences in long-term outcomes (height gain ∆HT at FH) and retesting results in 57 GHD children (M = 34, 59.6%) according to biochemical diagnosis: Group A (n = 25) with max GH peak at stimulation test < 8 µg/l, Group B (n = 19) with max GH peak between 8 and 10 µg/l and Group C (n = 13) with mean GH < 3 µg/l (neurosecretory dysfunction, NSD). At FH all patients underwent to retesting after at least 1 month off therapy. Median GH dose at FH was 0.025 mg/kg/day.

Results: 40/57 (70.2%) were pre-pubertal at diagnosis and showed a FH of –1.22 ± 0.93 SDS not significantly different in the three groups (P = 0.14) with a satisfactory ∆HT at FH of 1.37 ± 1.00 SDS (P = 0.08). Nonetheless, Group B showed the highest percentage of “poor responders” with 46% patients with ∆HT FH < 1SDS (vs 13% and 12% in Group A and C, respectively) and with 25% children not reaching Mid-parental height (MPH) vs 6% and 0% in Group A and C, respectively. At linear regression, low HT SDS (P = 0.0006), MPH difference (P = 0.0039) and low IGF-I SDS at baseline (P = 0.0035) were the most important predictive factors of ∆HT at FH. At FH attainment, GHD was reconfirmed in 28% (7/25), 10% (2/19) and 8% (1/13) patients in Group A, B and C, respectively.

Conclusion: A reduction of diagnostic cut-off at GH stimulation tests could better discriminate between “good” and “poor responders” and predict the persistence of GHD through transition. Nonetheless, GHD diagnosis solely based on provocative tests could exclude patients that might benefit of GH treatment. Group C response along with the predictive value of baseline IGF-I SDS bring back to lightNSD: should we consider an underlying hypothalamic derangement when the clinical presentation is strongly consistent with GHDbut pharmacological stimulation test is normal?