Evaluation of Growth Hormone Response by Oral Glucose Tolerance Test in the assessment of GH excess secretion in paediatric patients.

BALLERINI MG; FREIRE AV; CLEMENT MF; BRASLAVSKY D; RODRIGUEZ ME; ARCARI A; GRYNGARTEN MG; GONZALEZ S; MONTESE AM; DOMENÉ H; BERGADÁ I; ROPELATO MG

CABA

Congreso; XXVI Annual Meeting SLEP; 2016

Sociedad Latinoamericana de Endocrinología Pediátrica

Introduction:GH excess secretion is a rare disorder in children. In adults, a GH suppression concentration to ≤0.40 ng/mL after oral glucose tolerance test (OGTT) together with normal IGF-I concentration exclude this diagnosis. To our knowledge, the suppression of GH in response to OGTT using sensitive GH assays is not clearly stated for paediatric patients. Objective:To evaluate GH response to OGTT in a cohort of children with clinical suspicious of GH hypersecretion.Design and Methods:Cross-sectional analytical study. OGTT (1.75 g glucose/kg body weight to a maximum: 75 g) was performed in 10 patients [age: 13.8 (5.3?17.0) yrs] referred to our outpatient Endocrinology Department for assessment of tall stature (height ≥ +2.0 SDS) and/or the presence of pituitary adenoma without other pituitary secretory disorder. Blood samples were taken for GH (CLIA-Siemmens), insulin and glucose measurements (30 minutes intervals during 2 hours). GH dynamics [GH nadir concentration and area under the curve (AUC)] were compared with a control group of non-insulin resistant children without GH-axis disorders (n = 10). Basal IGF-I and IGFBP-3 were measured. Data were expressed as median (range). Results:In the control group, GH decreased at 30 minutes, maximal GH suppression was reached within 60?90 minutes [97thpercentile GH nadir concentration: 0.30 ng/mL] and AUC was 23 (6?133) ng/mL.120 min. In 8/10 patients, GH dynamic profile was similar to control group [GH nadir: 0.12 (0.07?0.20) ng/mL; AUC: 25 (10?105) ng/mL.120 min;p=NS]. Two patients did not reach GH nadir obtained for controls (0.60 and 0.80 ng/mL). Moreover, they presented a paradoxical rise at 30 minutes and elevated AUC: 286 and 294 ng/mL.120 min. IGF-I and IGFBP-3 were above +2.0 SDS in 4/8 and 6/8 patients, respectively, with normal GH response to OGTT and in 1 out of 2 patients with paradoxical response. Conclusion:Our finding of a GH nadir concentration of 0.30 ng/mL in OGTT in children using ultrasensitive assays was similar to the one suggested for adults. A paradoxical response, an elevated GH nadir and an increased AUC in patients with clinical suspicious of GH excess secretion alert to a close follow-up to further confirm diagnosis.