Ghrelin is a 28 amino acid, acylated peptide mainly produced in the P/D1 neuroendocrine cells of the stomach wall. The peptide stimulates growth hormone release by acting on both the pituitary and hypothalamus, but also stimulates ACTH and prolactin as well as gastric acid secretion and intestinal motility. Ghrelin also increases appetite and food intake. Expression of ghrelin protein and mRNA has been identified in high percentages of gastric neuroendocrine tumors (NETs) but also intestinal and pancreatic NETs. Theoretically, a ghrelinoma could cause acromegaly, diabetes mellitus, diarrhea and gastric acid hypersecretion. Small numbers of cases with elevated plasma ghrelin have been reported. However, patients often have non-specific symptoms, that do not resemble the theoretical syndrome of a ghrelinoma. This suggests a low biological activity of these elevated ghrelin levels, which could by related to the ratio of acylated ghrelin and unacylated ghrelin. At this time the clinical relevance of hyperghrelinemia for NETs remains limited. For complete coverage of all related areas of Endocrinology, please visit our on-line FREE web-text,
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