ESPE Abstracts

Background: Copeptin is secreted in isomolar amounts along with arginine vasopressin peptide from the posterior pituitary. Its stability makes it a perfect candidate for the endocrine approach in the diagnosis of AVP deficiency. Arginine-stimulated copeptin is a possible alternative for the water deprivation test. We wondered whether basal and stimulated copeptin secretion is related to growth hormone secretion status or independent of it.

Design and patients: This is a monocentric retrospective analysis of donated residual serum samples from 68 children and adolescents who underwent arginine or GHRH-arginine stimulation to test GH secretory capacity between 2018 and 2022.

Measurements: Copeptin was measured in baseline, 30-, and 60-min samples by BRAHMS Copeptin proAVP Kryptor immunofluorescence assay. GH was measured by in-house RIA calibrated against the WHO International Reference Preparation 98/574. Cut-offs for the diagnosis of GHD were 6.6 ng/ml for arginine (children, first test) and 15.9 ng/ml for GHRH-arginine (adolescents, retesting).

Results: According to the test results, there were 41 patients without GHD and 27 with GHD. The median baseline level of copeptin in the 41 patients without GHD was 5.6 (quartiles; 3.9 – 9.9) pmol/l, whereas it was 6.0 (3.1 – 9.0) pmol/l in patients with GHD (P=0.18). After 30 min, the median stimulated copeptin was 7.7 (5.3-11.2) pmol/l without GHD and 7.3 (4.3-11.3) pmol/l with GHD (P=0.49). After 60 min, the median stimulated copeptin was 7.8 (5.7-11.7) pmoil/l without GHD and 8.0 (4.9-11.4) pmol/l with GHD (P=0.67). In addition, there was no correlation between peak copeptin and peak GH concentrations.

Conclusions: The GH status of children does not appear to affect basal and arginine-stimulated serum copeptin concentrations.