Lab Test




  • The patient should be fasting 10-12 hours prior to collection.
  • The patient should not be on any antacid medication or medications that affect gastroentero-intestinal function, if possible, for at least 48 hours prior to collection.
  • Special GI preservative tubes may be obtained from Client Services (800-551-0488) or the Sendout Laboratory (248-551-9045).

Specimen Collection Criteria

Collect: One 10 mL EDTA tube containing GI Preservative. (This tube has a red top with a label stating that it contains GI preservative.)

  • Write Inter Science on label of the specimen.
  • Critical frozen. Send specimen for processing immediately after collection.

Physician Office/Drawsite Specimen Preparation

Critical frozen. Centrifuge to separate plasma from cells. Transfer plasma to plastic transport tube and freeze (-20°C/-4°F or below) immediately.

Preparation for Courier Transport

Transport: 3.0 mL plasma, frozen (-20°C/-4°F or below). (Min: 1.0 mL)

Rejection Criteria

  • Specimens not collected in EDTA with GI Preservative.
  • Specimens not collected and processed as indicated.


Monday - Friday.
Results available in 8-12 days.

Reference Range

12-75 pg/mL.

Test Methodology

Direct Radioimmunoassay.


Secretin is elevated in Zollinger-Ellison patients and in patients with duodenal ulcer. Secretin levels are low in patients with pernicious anemia and achlorhydria. Secretin secretion can be suppressed by Somatostatin, Cimetidine, and Methionine-Enkephalin.

Clinical Utility

Secretin is a 27 amino acid basic peptide produced by S cells and released by acid delivered into the duodenum. Secretin is released into the blood when duodenal pH drops below 4. Secretin shares structural similarity with Glucagon, Gastric Inhibitory

Polypeptide, Vasoactive Intestinal Polypeptide, PHIM, and Growth Hormone-Releasing Hormone. Secretin is a potent stimulus for bicarbonate secretion. Secretin also stimulates secretion of bile, release of insulin, and release of gastric pepsin in the stomach. Secretin inhibits glucagon release, intestinal motility, and prevents the uptake of water and sodium ions by the intestine. In normal patients, Secretin has little effect on gastrin levels, but stimulates gastrin greatly in Zollinger-Ellison patients.

CPT Code


Test Codes


Last Updated


Microtainer® and Vacutainer® are registered trademarks of Becton, Dickinson and Company.
UroVysion® is a registered trademark of Abbott Laboratories. ThinPrep® is a registered trademark of Hologic, Incorporated.


This directory currently reflects information only for specimens collected and/or processed at the
Farmington Hills, Grosse Pointe, Royal Oak, and Troy campuses.