Interleukin 6 (IL 6), Serum

Test Codes

EPIC: LAB1232099, Beaker: INTERLEUKIN, Quest: 34473

Department

Send Outs

Instructions

Patient Preparation:
No biotin supplements 48 hours prior to blood draw.

Specimen Collection Criteria

Collect: One Gold-top SST.

Also Acceptable: One plain Red-top tube.

Physician Office/Draw Specimen Preparation

Let specimen clot 30-60 minutes then centrifuge to separate serum from cells within two hours of collection. Transfer serum to a plastic transport tube and freeze (-20°C/-4°F or below).

Preparation for Courier Transport

Transport: 1.0 mL serum, frozen (-20°C/-4°F or below). (Minimum: 0.5 mL)

Rejection Criteria

• Grossly hemolyzed specimen.
• Received room temperature.
• Received frozen.
• Specimens not collected and processed as indicated. 

In-Lab Processing

Let specimen clot 30-60 minutes then centrifuge to separate serum from cells within two hours of collection. Transfer serum to a plastic transport tube and freeze (-20°C/-4°F or below).

Do not thaw. Cytokine levels may demonstrate diurnal variation. Recommend cytokine levels be determined at the same time of day for improved longitudinal comparison.

Transport: 1.0 mL serum, frozen (-20°C/-4°F or below). (Minimum: 0.5 mL)

Storage

Specimen Stability for Testing:

Room Temperature (20-26°C or 68-78.8°F): 24 hours
Refrigerated (2-8°C or 36-46°F): 48 hours
Frozen (-20°C/-4°F or below): 7 months

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

Daily.
Results available in 2-4 days.

Reference Range

By report.

Test Methodology

Immunoassay (IA)

Clinical Utility

IL-6, a multi-functional cytokine produced by a range of cells, plays a central role in host defense mechanisms, is involved in induction of B-cell differentiation, induction of IL-2 and IL-2 receptor expression and proliferation and differentiation of T cells. Elevated IL-6 concentrations are reported in a variety of autoimmune diseases (e.g., rheumatoid arthritis), proliferative diseases (e.g., mesangial proliferative glomerulonephritis), and malignancies (e.g., leukemia and lymphoma).

CPT Codes

83529

Contacts

Last Updated

12/19/2025