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wheezing, diarrhea, cramping

thymus, bronchus

excretion of 5-HIAA

Gastric ECLoma

Gastric carcinoid

None

Stomach

Usually discovered

during endoscopy

ECL = enterochromaffin-like cells; GRF = growth hormone-releasing factor; 5-HIAA = 5-hydroxyindoleacetic acid; PP = pancreatic polypeptide; VIP = vasoactive intestinal peptide.

ECL = enterochromaffin-like cells; GRF = growth hormone-releasing factor; 5-HIAA = 5-hydroxyindoleacetic acid; PP = pancreatic polypeptide; VIP = vasoactive intestinal peptide.

Figure 16-3. Operative photograph of a duodenal gastrinoma. The tumor has been identified and exposed by making a longitudinal duo-denotomy and palpating the duodenal wall between thumb and finger. This 3 mm tumor was identified in the submucosal space and is visible only as a "bump" from the mucosal surface shown here. There is no identifiable abnormality on the serosal side of the bowel wall.

Figure 16-3. Operative photograph of a duodenal gastrinoma. The tumor has been identified and exposed by making a longitudinal duo-denotomy and palpating the duodenal wall between thumb and finger. This 3 mm tumor was identified in the submucosal space and is visible only as a "bump" from the mucosal surface shown here. There is no identifiable abnormality on the serosal side of the bowel wall.

majority of tumors occur in the region of the duodenum or head of the pancreas. The "gastrinoma triangle" is defined by the cystic/common bile duct junc

Figure 16-4. Computed tomographic scan of the pancreas in a patient with multiple endocrine neoplasia (MEN) type I and a non-functioning tumor of the head of the pancreas.This patient was investigated because of his membership in a kindred with MEN type I and an elevated pancreatic polypeptide level. This otherwise asymptomatic tumor was resected by pancreaticoduodenectomy, and the patient is disease free at 4 years. The arrow indicates the neoplasm in the head of the pancreas.

Figure 16-4. Computed tomographic scan of the pancreas in a patient with multiple endocrine neoplasia (MEN) type I and a non-functioning tumor of the head of the pancreas.This patient was investigated because of his membership in a kindred with MEN type I and an elevated pancreatic polypeptide level. This otherwise asymptomatic tumor was resected by pancreaticoduodenectomy, and the patient is disease free at 4 years. The arrow indicates the neoplasm in the head of the pancreas.

basal acid output (BAO), maximal acid output (MAO), gastric output pH, and provocative tests. A normal BAO is < 5 mEq/hour for women and <10 mEq/hour for men. The criterion for ZollingerEllison syndrome is > 15 mEq for patients who have not previously had any gastric acid reduction surgery.17 However, the utility of acid output alone is limited because it can vary with the degree of hypercalcemia and can be elevated in patients with idiopathic hypersecretion. Therefore, BAO alone will never make the diagnosis of Zollinger-Ellison syndrome, and other tests are needed. MAO is obtained after a subcutaneous injection of pentagastrin (6 p,g/kg). A BAO-to-MAO ratio > 0.6 is indicative of Zollinger-Ellison syndrome but adds little to BAO alone. A gastric output pH > 3.0 in a patient who is not on antisecretory medications rules out Zollinger-Ellison syndrome. Approximately one-third of patients with Zollinger-Ellison syndrome can be diagnosed by a serum gastrin > 1,000 pg/mL with a gastric pH < 3.0.17 The other two-thirds of the patients require provocative tests16:

1. Secretin. Two units/kg Kabi secretin is given after two basal values of gastrin have been obtained. Then gastrin levels are measured at 2, 5, 10, 15, and 20 minutes. A positive test is an increase in gastrin > 200 pg/mL. The only cause for a false-positive result is achlorhydria, which can be ruled out with gastric juice pH. Secretin has become difficult to procure recently as it is no longer produced commercially, at least temporarily.

2. Calcium infusion test. Fifty-four mg/kg/hour of 10% calcium gluconate is given for 3 hours. Serum gastrin is measured at 120, 160, and 180 minutes with basal values. Fifty-six percent of patients with Zollinger-Ellison syndrome will have an increase > 395 pg/mL in serum gastrin. This test is contraindicated in patients with hypercalcemia or a history of cardiac arrhythmias and is therefore not commonly used in patients with MEN type I.

3. Standard meal test. Antral G-cell hyperplasia can mimic Zollinger-Ellison syndrome and should be considered in patients with mildly elevated gastrin/hyperchlorhydria but with negative secretin and calcium tests. During this test, two basal levels are obtained, and then serum gastrin is measured 30, 60, and 90 minutes after ingestion of a standard meal. A positive test is a serum gastrin increase > 100%, indicating the presence of G-cell hyperplasia. However, 30% of patients with Zollinger-Ellison syndrome also have a positive meal test; therefore, this test cannot exclude ZollingerEllison syndrome.

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