Growth Hormone (GH) Response to Oral Glucose Tolerance Test in the Assessment of GH Excess Secretion in Paediatric Patients

FREIRE A; CLEMENT F; RODRIGUEZ ME; DOMENÉ HM; BALLERINI MARÍA GABRIELA; ARCARI AJ; GRYNGARTEN M; MONTESE A; ROPELATO MG; KESELMAN A,; BRASLAVSKY D; GONZALEZ S; BERGADA I

Buenos Aires

Congreso; XXVI Congreso de la Sociedad Latinoamericana de Endocrinología Pediátrica.; 2016

Sociedad Latinoamericana de Endocrinología Pediátrica

ntroduction: GH excess secretion is a rare disorder in children.In adults, a GH suppression concentration to ≤0.40 ng/mLafter oral glucose tolerance test (OGTT) together with normalIGF-I concentration exclude this diagnosis. To our knowledge, thesuppression of GH in response to OGTT using sensitive GH assaysis not clearly stated for paediatric patients.Objective: To evaluate GH response to OGTT in a cohort ofchildren 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 performedin 10 patients [age: 13.8 (5.3?17.0) yrs] referred to our outpatientEndocrinology Department for assessment of tall stature(height ≥ +2.0 SDS) and/or the presence of pituitary adenomawithout other pituitary secretory disorder. Blood samples weretaken for GH (CLIA-Siemmens), insulin and glucose measurements(30 minutes intervals during 2 hours). GH dynamics [GHnadir concentration and area under the curve (AUC)] were comparedwith a control group of non-insulin resistant children withoutGH-axis disorders (n = 10). Basal IGF-I and IGFBP-3 weremeasured. 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 AUCwas 23 (6?133) ng/mL.120 min. In 8/10 patients, GH dynamic profilewas 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 didnot reach GH nadir obtained for controls (0.60 and 0.80 ng/mL).Moreover, they presented a paradoxical rise at 30 minutes and elevatedAUC: 286 and 294 ng/mL.120  min. IGF-I and IGFBP-3were above +2.0 SDS in 4/8 and 6/8 patients, respectively, withnormal GH response to OGTT and in 1 out of 2 patients with paradoxicalresponse.Conclusion: Our finding of a GH nadir concentration of 0.30ng/mL in OGTT in children using ultrasensitive assays was similarto the one suggested for adults. A paradoxical response, an elevatedGH nadir and an increased AUC in patients with clinical suspiciousof GH excess secretion alert to a close follow-up to furtherconfirm diagnosis.