Test Overview
Test Methodology

Direct RIA

Test Usage

Somatostatin is a cyclic peptide originally isolated from sheep hypothalami and shown to inhibit the release of Growth Hormone. Somatostatin is present primarily in three main forms: a 14 amino acid peptide, a 28 amino acid peptide ("Big" Somatostatin), and a 12,000 molecular weight ProSomatostatin. This assay measures only the 14 amino acid form of Somatostatin. All three forms of Somatostatin have similar biological properties and overall potencies. Somatostatin is a physiological regulator of Islet Cell and gastrointestinal functions, and is a suppressor of many pituitary hormones including Growth Hormone, Prolactin, and Thyrotropin (TSH). Somatostatin levels are often elevated in diabetics, but the levels return to normal upon correction of the hormonal and metabolic deficiencies present. In many cases of APUDomas including VIPoma, Insulinoma, Glucagonoma, and Gastrinoma, elevated levels of Somatostatin are found.

Reference Range *

< 25 pg/mL

* Reference ranges may change over time. Please refer to the original patient report when evaluating results.

Test Details
Days Set Up
Monday - Friday
Analytic Time

9 - 11 days

Soft Order Code
MiChart Code
  • Somatotropin Release Inhibiting Factor
Reference Laboratory
Mayo FSOMA (90172) (Interscience)
Special Testing
Specimen Requirements
Collection Instructions

Collect specimen in "G.I. Preservative" tube (EDTA tube with preservative), available from MLabs. For baseline determination collect specimen following an overnight (10-12 hour) fast. Following collection, centrifuge, aliquot plasma into a plastic vial, and freeze. If possible, discontinue insulin medication prior to collection.

Special Handling

Fasting specimen. Requires special "G.I. Preservative" tube.

Normal Volume
1.5 mL plasma
Minimum Volume
1 mL plasma
Additional Information

Test sent to Mayo Medical Laboratories; performed by Interscience Institute.

CPT Code
Fee Code