ESPE Abstracts (2015) 84 P-2-392

Unaltered Ratio of Circulating Levels of GH Isoforms after Administration of Different GH Provocative Tests in a Population of Short Stature Children

Antonello Rigamontia, Cristina Meazzab, Martin Bidlingmaierc, Valentina Muratored, Luparia Martinad, Silvia Binia, Sara Paganib, Silvano Cellaa & Mauro Bozzolab

aUniversity of Milan, Milan, Italy; bUniversity of Pavia, Fondazione IRCCS Policlinico San Matteo, Pavia, Italy; cMedizinische Klinik und Poliklinik IV, Klinikum der Universität München, Munich, Germany; dFondazione IRCCS Policlinico San Matteo, Pavia, Italy

Background: Human GH is a heterogeneous protein hormone consisting of several isoforms, the most abundant being 22 kDa- and 20 kDa-GH. The availability of analytical methods to measure these GH isoforms might represent a valuable diagnostic tool to investigate GH secretion in short stature.

Objective and hypotheses: Aim of the present study was to measure circulating levels of 22 kDa- and 20 kDa-GH in children with different diagnosis of short stature such as idiopathic short stature (ISS), isolated GH deficiency (GHD), short stature by bioinactive GH (BIO-SS) or GHD subjects at time of retesting at the end of GH therapy (Re-GHD), using different GH provocative tests (insulin, arginine, GHRH+arginine or glucagon).

Method: A total of 118 short-statured children (males/females: 72/46; age range 1.1–15.6 years) after administration of insulin, arginine, GHRH+arginine or glucagon was consecutively recruited from January 2010 to December 2014. The results were analysed subdividing the study population on the basis of the administered GH provocative test or the diagnosis of short stature (ISS, GHD, BIO-SS or Re-GHD). The data are expressed as mean±standard deviation.

Results: When considering GH provocative test, there were no statistically significant differences in the ratio of GH peak 22/20 kDa (insulin: 7.0±2.7; arginine: 9.2±7.2; GHRH+arginine; 7.0±2.9; glucagon: 7.7±3.3). Similarly, when considering diagnosis of short stature, there were no statistically significant differences in the ratio of GH peak 22 kDa/20 kDa (ISS: 7.0±8.2; GHD: 5.4±3.9; Re-GHD: 5.4±3.0; BIO-SS: 7.1±1.8).

Conclusion: The main GH provocative tests currently used in paediatric endocrinological practice, which are based on different neuroendocrine mechanisms, stimulate a similar secretion of GH isoforms. Moreover, different causes of short stature are not associated with an unbalance in GH isoforms.