Insulin, Free (Bioactive)

Insulin, Free and Total, Serum

Test Codes

EPIC: LAB1232217, Beaker: Insulin Free, Quest: 36700

Department

Send Outs

Instructions

The patient should be fasting overnight prior to specimen collection.

Specimen Collection Criteria

Collect (preferred specimen): One Gold-top SST tube.

Also acceptable: One plain Red-top tube.

Physician Office/Draw Specimen Preparation

Let specimen clot 30-60 minutes and centrifuge to separate serum from cells within 2 hours of collection. Transfer serum to a plastic transport tube and refrigerate (2-8°C or 36-46°F).

Preparation for Courier Transport

Transport: 0.5 mL serum, refrigerated at (2-8°C or 36-46°F). (Minimum: 0.3 mL)

Rejection Criteria

• Hemolyzed specimens.
• Received room temperature.
• Specimens not collected and processed as indicated.

In-Lab Processing

Let specimen clot 30-60 minutes and centrifuge to separate serum from cells within 2 hours of collection. Transfer serum to a plastic transport tube and refrigerate (2-8°C or 36-46°F).

Transport: 0.5 mL serum, refrigerate (2-8°C or 36-46°F). (Minimum: 0.3 mL)

Storage

Specimen Stability for Testing:

Room Temperature (20-26°C or 68-78.8°F): 12 hours
Refrigerated (2-8°C or 36-46°F): 7 days
Frozen (-20°C/-4°F or below): 28 days

Specimen Storage in Department Prior to Disposal:

Specimen retention time is determined by the policy of the reference laboratory. Contact the Send Outs Laboratory with any questions.

Laboratory

Sent to Quest Diagnostics, Wood Dale, IL.

Performed

Sunday, Tuesday, Thursday.
Results available in 4-7 days.

Reference Range

Insulin, Free

1.5-14.9 uIU/mL

Insulin levels vary widely in specimens taken from non-fasting individuals.
Insulin analogues may demonstrate non-linear cross-reactivity in this assay. Interpret results accordingly.

Test Methodology

Immunoassay (IA)

Clinical Utility

Insulin, Free (Bioactive) - The free insulin measurement is helpful in interpreting blood sugar concentration and its relationship to insulin injections in insulin-treated patients with insulin antibodies.

CPT Codes

83527

Contacts

Last Updated

12/17/2025