Test Directory

Test Code
INSU
Test Name
Insulin
CPT Codes
83525
Expected Turnaround Time
1 - 3 days
Clinical Utility

Can be used to evaluate insulin producing neoplasm (islet cell tumor, insulinoma) or pancreatic islet cell hyperplasia; work-up for hypoglycemia to evaluate insulin production in diabetes mellitus. Insulin-secreting tumors usually present with hypoglycemic symptoms and are diagnosed by a 72-hour prolonged fast. After 72 hours of fasting, an insulin concentration greater than 6 mU/L indicates an insulinoma. Factitious hypoglycemia from exogenous insulin shows increased insulin, but not proinsulin or C-peptide.

Specimen and Container Info

Specimen Type: Serum

Preferred Collection Container: Gold Top, Serum Separator

Alternate Collection Container: Red Top, Separator

Minimum Acceptable Volume: 1.0 mL

Processing and Submission Instructions

Separator tubes: Contains clot activator and gel for separating serum from cells, but not anticoagulant. Separate serum from cells as soon as the clot has formed (30 minutes). If specimen is centrifuged before clotting is complete, a fibrin clot will form on top of the cell. This may cause the gel barrier to not be intact and could cause improper separation of serum and cells, possibly affecting test results.

Patient Preparation
Fasting
Transport Instructions

Transport to the laboratory refrigerated.

Stability Requirements

Refrigerated

48 hours

Methodology
Chemiluminescent Immunoassay
Reference Intervals
Performing Location
Roble Road Core Laboratory
Testing Schedule
Routine, daily