Some patients with peptic ulcer disease will have mildly elevated serum gastrin levels. The gastrin stimulation test following secretin injection can help distinguish patients with gastrinoma and Zollinger-Ellison syndrome from patients with secondary causes for the elevated gastrin levels.

Patient selection: A patient with gastric acid hypersecretion and a high gastrin concentration (> 500 pg/mL, about 5 times the upper limit of normal) has Zollinger-Ellison Syndrome and does not need additional diagnostic testing.


Patient preparation: overnight fasting


Specimen: serum, separated immediately and frozen if immediately if testing delayed


dose of secretin to inject in units =

= (2-3 units) * (body weight in kilograms)



(1) Collect 2 fasting blood samples.

(2) Inject the secretin intravenously (IV) in 20-30 seconds.

(3) Collect samples at 2, 5, 10, 15, 20 and 30 minutes after the injection.

(4) Test all samples for gastrin.


basal fasting value in pg/mL =

= AVERAGE(2 fasting blood samples before secretin injection).


maximal increase in gastrin level in pg/mL after stimulation =

= (maximal value after secretin injection) - (basal fasting value prior to secretin)



• A maximal increase >= 200 pg/mL is considered a "positive" test and is supportive for the diagnosis of Zollinger-Ellison Syndrome.

• An increase of 100 - 199 is considered suggestive (some consider positive).

• A few patients without gastrinomas may show increases up to 300 ng/mL.

• A normal person shows no increase or a mild decrease in gastrin levels.

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