ESPE Abstracts

Background: The diagnosis of GH deficiency is challenged by the suboptimal accuracy of GH stimulation tests. Overnight GH sampling (OGS) may be useful in the diagnosis of growth disorders.

Objectives: To establish if 1) the reduced number of spontaneous overnight GH profile peaks (SOGPP) is associated with hypothalamo-pituitary (H-P) abnormalities on MRI, 2) these children benefit from GH treatment.

Methods: We retrospectively reviewed a cohort of 212 patients (67%M, 33%F, aged 0.4-17.5y) admitted for 12-hour overnight GH profiles (20-minute sampling) between 2010-2023. Inclusion criteria: height ≤-2SDS or height velocity ≤-1.5 SDS, IGF1<0 SDS, normal response to glucagon test (peak GH≥6.7μg/l). Auxological data and annual mean GH daily dose were collected at time of profiling, 1y and 3y of treatment, and final height (FH, n = 34). ΔHeightSDS was calculated as difference between height SDS at 1y and 3y post treatment and FH vs that at diagnosis.163/212(77.3%) patients had <3 spontaneous GH peaks ≥6.7μg/l. 100/156 patients with reduced number of SOGPP were treated with GH. Pituitary MRIs were available in 161 patients. Classification of OGS severity (GH peaks): 2 (n = 55); 1 (n = 56); 0 (n = 52). H-P abnormalities grading: normal MRI (n = 61); isolated small anterior pituitary (SAP) (n = 74); SAP with ectopic posterior pituitary (EPP) and normal/thin stalk (n = 20); SAP with absent PP and normal/thin stalk (n = 6).

Results: Pathological overnight profiles were associated with H-P abnormalities on MRI (P = 0.03; 95% CI 0.06-0.22), with a trend towards a correlation between the severity of OGS and type of H-P anomalies (P = 0.07). Children with reduced number of SOGPP treated with GH (mean dose 11±16 mcg/kg/d) showed a greater improvement in Δheight SDS at the 3y (P = 0.01; 95% CI 0.32-1.27) and at FH (P <0.01; 95% CI 0.75-2.58) FU compared to untreated patients.A trend towards a greater improvement in Δheight SDS at 1y and 3y has been found in children treated with higher annual mean GH daily dose (P = 0.09 and P = 0.07, respectively), but not at FH.

Conclusion: Children with reduced number of SOGPP display a wide range of H-P anomalies on MRI that correlate with the severity of overnight GH dysfunction. They benefit from GH treatment, with better ΔFH SDS than those untreated, and with dose-response effect up to 3y of treatment. FH data on larger numbers of patients will ultimately clarify the benefits of GH treatment in this condition. The study provides convincing evidence, on a large cohort, that OGS represents a valuable diagnostic method for patients with growth disorders but normal GH stimulation tests.