I. Gastrin-secreting tumor (or tumors) from non-beta islet cells of pancreas results in greatly increased gastric HCl production
II. Tumors are usually unresectable; sometimes too small to find; about 2/3 are malignant
III. Although the hallmark is ulcers in wider geographic distribution than normal, 75% of ulcers in Z-E sd are single ulcers in the duodenal bulb.
IV. 1/3 of pts have diarrhea, which usually precedes ulcer development; 7% have diarrhea and never develop and ulcer
V. Consider dx especially when ulcers are
- Refractory to med. therapy
- Giant
- Multiple
- Not limited to duodenal bulb
- Located in a surgical anastomosis
- Associated with diarrhea not secondary to drugs
VI. Dx based on serum gastrin concentration > 1000 pg/ml (nl < 150)
- Causes for moderately elevated gastrin ( < 1000): retained antrum after gastric surgery, g-cell hyperplasia, postvagotomy plus pyloroplasty, pernicious anemia, and a small proportion of nl pts with DU
- Make sure to stop H2 blockers > 12h before measuring gastrin b/c will raise it
- Provocative tests can confirm:
- Secretin infusion test: in Z-E, gastrin level rises < 1/2 after injection of secretin; if not, it remains steady or falls
- Gastric acid monitoring with pentagastrin infusion: basal: maximal acid output > 0.6 suggests Z-E
VII. Tx
- Gastrectomy traditional tx of choice
- Highly selective vagotomyis also used
- High-dose H-2 blockers or omeprazole are used to calm things down before surgery