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Test Code LAB1235221 Somatostatin (Somatotropin Release-Inhibiting Factor, SRIF)

Important Note

Mayo test code: FSOMA

Performing Laboratory

Inter Science Institute

Specimen Required

Patient preparation:

 1. Patient should be fasting 10-12 hours prior to collection.

 2. Patient should not be on any medications that affect insulin secretion or intestinal motility, if possible for at least 48 hours prior to collection.

Specimen Type: Plasma

Container/Tube: EDTA tube containing GI preservative: EDTAGI

Specimen Volume: 1 mL

Collection Instructions: Collect 10 mL of blood in special tube containing G.I. Preservative (T125). Specimen should be separated immediately and send 3 mL plasma frozen as soon as possible.

Specimen Minimum Volume

1 mL

Specimen Stability Information

Specimen Type Temperature Time Special Container
GI Plasma Frozen 90 days  

Reject Due To

Hemolysis Mild reject; Gross reject
Lipemia Mild reject; Gross reject
Icterus NA
Other Specimens other than Plasma collected in GI preservative (T125). Test is strict frozen

Day(s) Performed

Performed Monday through Friday

Report avaiable within 7 to 11 days

Method Name

Direct Radioimmunoassay (RIA)

CPT Code Information

84307

Clinical Information

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 Values

Up to 25 pg/mL