A 35-year-old man comes to the physician because of ...
Can you please explain how gastrin relates to the physical exam findings in the patient?
I believe the logic behind it is patient has pain and black stool, suggesting peptic ulcer with bleeding. Since pain is not relieved by antiacid and H2 blockers, it suggests ectopic source to stimulate the excessive acid. Among all, gastrin by ZE syndrome fits the most.