ESPE Abstracts (2019) 92 P2-154

Determinants of the Peak GH Response of the Glucagon Stimulation Test in Slowly Growing Children

Jean De Schepper 1,2, Charline Dewulf2, Marghareta Craen2, Martine Cools2, Inge Gies1

1UZ Brussel, Brussels, Belgium. 2UZ Gent, Ghent, Belgium

Background/Aim: Currently, the minimum of the GH peak (pGH) to GH provocative stimuli, including the glucagon stimulation test (GST), has been arbitrary set in children at 7 µg/L, irrespective of gender and age. Several doses (fixed or per bodyweight) and ways of administration (IM or SC) of glucagon are being used in daily practice. This retrospective study explores the influence of gender, age, and adiposity on the pGH after a maximally effective glucagon stimulation (0.1 mg/kg (max 2 mg) IM) and the relationship between blood glucose (BG) and GH dynamics.

Methods: Auxological and hormonal data of 84 (49 male) slowly growing (growth velocity < P25) children and adolescents (age < 18 years), who underwent a GST (in 11 subjects after priming) in 2013-2014 in two University Hospitals were retrieved. In 26 of them an insulin tolerance test (ITT) had been performed before and in 3 after the GST. In all children, GH was measured by the IDS-iSYS assay.

Results: Median(range) age was 8.1 (0.8-17.5) years and height sds was – 2.7 (–6.3 – 0.8). Median pGH after GST was similar in males and females, but significantly (P< 0.005) higher than after ITT in non-primed subjects (8.4 (1.2-16.3) vs 4.4 (0.9-6.9) µg/L), in whom pGH correlated significantly with age (r=0.29, P <0.05) and serum IGF-1 (r= 0.41; P<0.005). In 28 (33 %) of the 84 children pGH after GST was lower than 7 µg/L. BG during GST became lower than 50 mg/dl in 30 (36 %) subjects. BG nadir correlated with age (r= 0.31; P< 0.005), weight SDS (r=0.23; P<0.05) and basal BG (r= 0.48; P<0.005), but not with the pGH.

Conclusion: The GST, when performed as a second test, in a dose of 0.1 mg/kg bodyweight, is more powerful in releasing GH than the ITT. The pGH after GST is dependent on age in a non-primed condition, but independent of gender or weight status. We propose to use the GST as a first line GH test to avoid the need for a second ITT test, given its higher potency, independency of weight status and low risk of hypoglycemia.

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