Ghrelin is a somatotrophic, orexigenic and adipogenic hormone that has an important homeostatic role by linking regulatory systems for growth and energy balance. Ghrelin- secreting neuroendocrine tumors are rare, but we had the opportunity to study a 71 years old female patient with a gastric ghrelinoma. The patient was submitted to gastroenterological examination after having episodes of diarrhea, and small subepithelial polyp (5 mm) was revealed on gastroscopy. Pathohystological analysis after endoscopic biopsy proved it to be a well-differentiated neuroendocrine tumor (Ki 671%) with immunostaining positive for general neuroendocrine markers (CgA and synaptophysin +++) as well as for ghrelin (+++). The patient was otherwise in good health condition, was slightly obese (BMI-27.4 kg/m2) and had no clinical signs of acromegaly. Serum ghrelin level was elevated. It has been previously shown in gastrectomized patients that short-term ghrelin administration during hyperinsulinemic euglycemic clamp induces a transient increase in GH levels, a decrease in IGF1 level, and a decrease in C-peptide level, thus having a negative influence on insulin secretion and glucose consumption. Our patient had normal IGF1 level for age and gender (155 ng/ml, ref. 64188), but her basal GH level was elevated (3.9 ng/ml), with no signs of GH-producing pituitary tumor. Her basal insulin level was normal (17.6 mmol/l), with marked increase during glucose tolerance test ((300 mmol/). We performed a hyperinsulinemic euglycemic clamp and found significantly reduced M value (2.83 mg/kg bw per min). We conclude that chronic hyperghrelinemia may induce insulin and GH resistance.
03 - 07 May 2008
European Society of Endocrinology