The patient presented with multiple stomach ulcers and thickened gastric folds. To check for a possible gastrinoma, doctors measured the patient's serum gastrin level after stopping proton pump inhibitor therapy for a week, and performed a secretin stimulation test. Based on the results, further testing was recommended to localize a gastrinoma.

1. Suspected gastrinoma
Endoscopy shows
multiple stomach ulcers
& thickened gastric folds
Check serum gastrin
level off PPI therapy for
1 week
Secretin
stimulation
test
No
gastrinoma
Check gastric pH off PPI
therapy for 1 week
No
gastrinoma
Further
testing to
localize
gastrinoma
>1000
pg/mL
<110
pg/mL
110-1000
pg/mL
Negative
Positive
pH>4
pH≤ 4