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

Reporting Name

Somatostatin (Plasma)

Performing Laboratory

Inter Science Institute

Specimen Type

GI Plasma


Specimen Required


1. Patient should be fasting 10 to 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: GI Plasma

Container/Tube:

Preferred: EDTA tube containing GI preservative (T125)

Acceptable: EDTA purple top plasma tube

Specimen Volume: 3 mL

Collection Instructions:

1. Collect 10 mL of blood in special tube containing GI Preservative (T125), EDTA purple-top plasma tube is acceptable.

2. Specimen should be separated immediately.

3. 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 180 days

Reference Values

Up to 25 pg/mL

Day(s) Performed

Monday through Friday

Test Classification

This test was developed and its performance characteristics determined by Inter Science Institute. It has not been cleared or approved by the US Food and Drug Administration. The FDA has determined that such clearance or approval is not necessary.

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 Pro-somatostatin. 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.

Report Available

9 to 11 days

Reject Due To

Gross hemolysis Reject
Gross lipemia Reject
Gross icterus Reject

Method Name

Direct Radioimmunoassay (RIA)