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

CONTEXT: The 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.

OBJECTIVE: The 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).

DESIGN: Prospective experimental cross-sectional study.

SETTINGS: The study was conducted at the Endocrinology department of the University Hospital of a Coruña, Spain.

PARTICIPANTS AND METHODS: We 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.

INTERVENTIONS: The intervention consisted of orally administering 75g oral glucose administration; GH was obtained every 30min for a total of 300min.

MAIN OUTCOME MEASUREMENT: Peak GH area under receiver operating characteristic curve (ROC-AUC) following LOGT.

RESULTS: Peak 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 1.0μg/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.

CONCLUSIONS: The LOGT could be a cheap, safe, convenient and effective test for the diagnosis of AGHD.