|
Overview :
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)
Method:
(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)
Interpretation:
•
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.
|