Abstract
Background: Re-testing for GH secretion is needed to confirm the diagnosis of GH deficiency (GHD) after adult height achievement in childhood-onset GHD (COGHD).Aim: 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.Patients and methods: 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 <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.Results: Forty-six subjects with a GH peak to ITT ≥6μg/L and 42 with GH peak <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.Conclusions: 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.
Highlights
Growth hormone deficiency (GHD) is a well-recognized clinical entity in adults
The aim of the study was to evaluate the reliability of the GHRHarg testing in the diagnosis of permanent GHD in childhood-onset GHD (COGHD) based on (1) their GH response to insulin tolerance test (ITT)
The median GH response to GHRHarg in the entire cohort based on their underlying etiology and the number of pituitary defects is reported in Table 2 In particular, the GH response was significantly lower in congenital growth hormone deficiency (CGHD) and tumoral GHD (TGHD) patients than in idiopathic GHD (IGHD) subjects and in multiple pituitary hormone defects (MPHD) patients compared to isolated GHD
Summary
Growth hormone deficiency (GHD) is a well-recognized clinical entity in adults. It is characterized by abnormalities in substrate metabolism, body composition, physical, and psychosocial functioning, all of which improve after GH replacement (1). The last international consensus statement (2), recommended re-testing for GH secretion young adults with childhood-onset GHD (COGHD) and evidence of hypothalamic-pituitary disease for whom there is intention to treat. This includes patients (1) with signs and symptoms of hypothalamic-pituitary disease from endocrine, structural, and/or genetic causes; (2) who received cranial irradiation or brain tumor treatment; and (3) who presented traumatic brain injury or subarachnoid hemorrhage. Re-testing for GH secretion is needed to confirm the diagnosis of GH deficiency (GHD) after adult height achievement in childhood-onset GHD (COGHD)
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