AUTHOR=Patti Giuseppa , Noli Serena , Capalbo Donatella , Allegri Anna Maria Elsa , Napoli Flavia , Cappa Marco , Ubertini Grazia Maria , Gallizia Annalisa , Notarnicola Sara , Ibba Anastasia , Crocco Marco , Parodi Stefano , Salerno Mariacarolina , Loche Sandro , Garré Maria Luisa , Tornari Elena , Maghnie Mohamad , Di Iorgi Natascia 

TITLE=Accuracy and Limitations of the Growth Hormone (GH) Releasing Hormone-Arginine Retesting in Young Adults With Childhood-Onset GH Deficiency

JOURNAL=Frontiers in Endocrinology

VOLUME=10

YEAR=2019

URL=https://www.frontiersin.org/journals/endocrinology/articles/10.3389/fendo.2019.00525

DOI=10.3389/fendo.2019.00525

ISSN=1664-2392

ABSTRACT=<p><bold>Background:</bold> Re-testing for GH secretion is needed to confirm the diagnosis of GH deficiency (GHD) after adult height achievement in childhood-onset GHD (COGHD).</p><p><bold>Aim:</bold> To define the cut-off of GH peak after retesting with GH-releasing hormone plus arginine (GHRHarg) in the diagnosis of permanent GHD in COGHD of different etiology.</p><p><bold>Patients and methods:</bold> Eighty-eight COGHD (median age 17.2 y), 29 idiopathic GHD (IGHD), 44 cancer survivors (TGHD) and 15 congenital GHD (CGHD) were enrolled in the study; 54 had isolated GHD (iGHD) and 34 had multiple pituitary hormone deficiencies (MPHD). All were tested with insulin tolerance test (ITT) and GHRHarg. IGHD with a GH response to ITT ≥6μg/L were considered true negatives and served as the control group, and patients with a GH response &lt;6μg/L as true positives. Baseline IGF-I was also measured. The diagnostic accuracy of GHRHarg testing and of IGF-I SDS in patients with GHD of different etiologies was evaluated by ROC analysis.</p><p><bold>Results:</bold> Forty-six subjects with a GH peak to ITT ≥6μg/L and 42 with GH peak &lt;6 μg/L showed a GH peak after GHRHarg between 8.8–124μg/L and 0.3–26.3μg/L, respectively; 29 IGHD were true negatives, 42 were true positives and 17 with a high likelihood GHD showed a GH peak to ITT ≥6μg/L. ROC analysis based on the etiology indicated the best diagnostic accuracy for peak GH cutoffs after GHRHarg of 25.3 μg/L in CGHD, 15.7 in TGHD, and 13.8 in MPHD, and for IGF-1 SDS at −2.1 in CGHD, −1.5 in TGHD, and −1.9 in MPHD.</p><p><bold>Conclusions:</bold> Our findings indicate that the best cut-off for GH peak after retesting with GHRHarg changes according to the etiology of GHD during the transition age. Based on these results the diagnostic accuracy of GHRHarg remains questionable.</p>