Oral glucose-stimulated growth hormone (GH) test in adult GH deficiency patients and controls: Potential utility of a novel test

ContextThe diagnosis of adult GH deficiency requires confirmation with a GH stimulation test. Oral glucose (OG) administration affects GH secretion, initially decreasing and subsequently stimulating GH secretion.ObjectiveThe aim of this study was to investigate the diagnostic efficacy and safety of a long OG test (LOGT) as a stimulus of GH secretion for the diagnosis of adult GH deficiency (AGHD).DesignProspective experimental cross-sectional study.SettingsThe study was conducted at the Endocrinology department of the University Hospital of a Coruña, Spain.Participants and methodsWe included 60 (40 women) AGHD patients (15) and controls (45) paired 1:3, of similar age, sex and BMI. The area under the curve (AUC) and peak were calculated for GH. The Mann-Whitney test was used to compare the different groups. ROC curve analyses were used. p-Values < 0.05 were considered as statistically significant.InterventionsThe intervention consisted of orally administering 75 g oral glucose administration; GH was obtained every 30 min for a total of 300 min.Main outcome measurementPeak GH area under receiver operating characteristic curve (ROC-AUC) following LOGT.ResultsPeak GH (μg/L) levels were lower in the AGHD patients (0.26 ± 0.09) than in the controls (4.00 ± 0.45), p < 0.001. After LOGT, with the ROC plot analysis the best peak GH cut-point was 1.0 μg/L, with 100% sensitivity, 78% specificity, ROC-AUC of 0.9089 and 81.82% accuracy. There were no relevant adverse events during any of the LOGT.ConclusionsThe LOGT could be a cheap, safe, convenient and effective test for the diagnosis of AGHD.