April - June 2015, Volume 11, Issue 2

Aydin C, Ersoy R, Ozdemir D, Cuhaci N, Arpaci D, Usluogullari CA, Ustu Y, Baser H, Dirikoc A, Cakir B

Comparison of Growth Hormone Suppression Response after Oral and Intravenous Glucose Tolerance Tests in Healthy Adults

Acta Endo (Buc) 2015, 11 (2): 202-207
doi: 10.4183/aeb.2015.202

Objective. Personal discrepancies in gastrointestinal physiology might influence responses to GH suppression during OGTT. We aim to compare growth hormone (GH) response during oral glucose tolerance test (OGTT) and intravenous glucose tolerance test (IVGTT). Methods. Data of 18 healthy volunteers were analyzed in the study. Subjects were firstly evaluated with standard 75-g OGTT. In subjects with serum glucose <100 mg/dL at basal state and <140 mg/dL at 120th minute of oral loading, IVGTT was performed after at least 3 days. Serum glucose, insulin and GH levels were measured during two tests. Results. Basal GH levels had a wide distribution ranging from 0.00005 μg/L to 0.768 μg/L (median 0.0145 μg/L). Mean nadir GH level during OGTT was obtained at 60th minute and it was 0.0376 μg/L(range 0.00011-0.387, median 0.0016 μg/L, SD: 0.095, SEM: 0.038). Nadir GH level during IVGTT was observed at 10th minute and it was 0.112 μg/L(range 0.0005-0.770 μg/L, median 0.0053 μg/L, SD: 0.242, SEM: 0.057). There was a statistically significant difference between nadir GH levels obtained during IVGTT and OGTT (p=0.028). Conclusions. We found that mean nadir GH level was significantly higher during IVGTT in healthy subjects. This is a preliminary study and further large scale studies are required to suggest that IVGTT may be used in the diagnosis and follow-up of patients with acromegaly as an alternative to or instead of OGTT.

Keywords: Growth hormone, oral glucose tolerance test, intravenous glucose tolerance test.

Correspondence: Reyhan Ersoy MD, Yildirim Beyazit University, Faculty of Medicine, Department of Endocrinology and Metabolism Lodumlu Mevkii, Bilkent Yolu No 2, Ankara, 06800, Turkey, E-mail: reyhanersoy@yahoo.com.tr