Gastrin 478X Clinical Use Clinical Background • Diagnose gastrinoma Gastrin is a polypeptide hormone • Differential diagnosis of peptic ulcer secreted by the G cells of the gastric antral mucosa and proximal duodenal disease and gastrin-secreting tumors Test Alphabetical cells. Gastrin is a potent stimulator of Reference Range antral acid secretion, and also has Section pg/mL trophic actions on the parietal cells, Adults <100 chief cells, and enterochromaffin-like cells in the oxyntic mucosa. Gastrin Children levels increase with food intake 5-7 y 13-64 (protein, amino acids) and age. Levels decrease with gastric acid Interpretive Information secretion. • Gastrinoma In Zollinger-Ellison syndrome (ZE • Pernicious anemia syndrome), a pancreatic neoplasm produces large amounts of gastrin, • Atrophic gastritis with anacidity which in turn stimulates excess gastric Zollinger-Ellison syndrome: gastrin acid secretion and peptic ulcer disease. levels >200 pg/mL (Roy PK, et al. A variety of pathological, but non- Medicine. 2000;79:379-411.) tumorous, disorders in which gastric acid secretion is low also lead to ®’ ®’ Zantac , Prilosec , and pepsid elevations in blood gastrin; these interfere with gastrin production. disorders include pernicious anemia and atrophic gastritis with anacidity. Secretin- or calcium-stimulation tests can assist in differentiating tumors from gastrin secreted by the antrum in patients with slight or moderate hypergastrinemia. Method • Immunochemiluminometric assay (ICMA) • Analytical sensitivity: 10 pg/mL • Analytical specificity: detects gastrin (G17); 7% cross reactivity with big gastrin (G34); does not cross react with G13. Specimen Requirements 1 mL frozen serum 0.5 mL minimum No additive red top preferred SST red top acceptable Overnight fasting is required. 81.