Endocrine Abstracts

Objectives: Current provocative tests for GH deficiency (GHD) are neither 100% sensitive nor specific. GH neurosecretory dysfunction (NSD) refers to the presence of growth failure, normal stimulated GH responses, but impaired spontaneous GH secretion. We describe our experience in managing GHNSD over 7 years.

Methods: We retrospectively reviewed a cohort of 106 children admitted for 12-h overnight GH profiles (with 20-min sampling) between 2010 and 2016. Auxological, biochemical and neuroradiological data were collected at the time of profiling, at 1-year and 3-year follow-up. GHNSD was defined when the overnight profile showed <3 spontaneous peaks of GH ≥6.7 ug/l.

Results: Seventy-nine boys and 27 girls presenting at a mean age of 7.6±3.8 years, with a mean height SDS of −3.3±1.5 and a mean height velocity (HV) SDS of −2.1±1.7 SDS were included. 103 patients had IGF-1 concentrations below the reference range mean. All had normal GH peaks to provocation (mean 12.7±5.7 μg/l). 85 patients had GHNSD, with auxological outcomes available for 53 at 1 year and 30 at 3 years (39 and 25 treated with GH respectively). Height SDS was not significantly different between the treated and untreated groups (1-year: −3.4±2.8 vs −3.3±1.4, P=0.952; 3-year: −2.3±1.0 vs −3.4±1.9, P=0.068) but HV SDS was significantly increased in the GH-treated group (1-year: +1.9±2.3 vs −1.8±1.6, P=0.001; 3-year +1.4±1.7 vs −1.4±1.5, P=0.002). Height SDS also significantly increased at 3 years with treatment (+1.2±1.0 vs +0.1±0.6, P=0.03). Exclusion of patients with syndromes affecting growth or attaining puberty during follow-up did not reveal any difference in findings. Anterior pituitary hypoplasia was present in 71% of GHNSD patients and 54.5% of patients with a normal GH profile (P=0.306), whilst other endocrine deficits were present only in patients with GHNSD (12.9%).

Conclusions: Children with abnormal auxology and a normal GH peak to provocative testing may warrant an overnight GH profile to identify GHNSD. Children with GH deficiency secondary to NSD display similar responses to GH replacement as in frank GHD, and therefore should be considered part of the spectrum of GHD disorders. Longer-term outcomes including adult height data are still required to establish the long-term efficacy of treating GHNSD.