Summary & Overview
CPT 83529: Interleukin-6 (IL-6) Immunoassay
CPT code 83529 represents a laboratory chemistry test that quantifies interleukin‑6 (IL‑6) in serum or plasma, typically performed using immunoassay methods. IL‑6 is a key inflammatory cytokine, and measuring its level has clinical relevance in diagnosing and monitoring inflammatory states related to infection, autoimmune disease, cardiovascular conditions, and some malignancies. Nationally, use of IL‑6 testing has grown as clinicians seek biomarkers to guide care in complex inflammatory and infectious presentations.
Key payers discussed include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find clinical context for the assay, common sites of service, and what the code covers for billing purposes. The publication summarizes typical service lines, payer coverage considerations, and operational benchmarks where available. It also outlines common reporting formats and coding implications for laboratories and billing teams.
This summary prepares clinical laboratory directors, revenue cycle managers, and policy analysts to understand the role of CPT code 83529 in care pathways and payer interactions, and to locate more detailed benchmarks and policy updates in the full report. Data not available in the input.
Billing Code Overview
CPT code 83529 describes a chemistry test for quantifying interleukin-6 (IL-6) in a biological specimen such as serum or plasma. The assay commonly uses immunoassay techniques that rely on antibody–antigen reactions to measure IL-6 concentration. IL-6 is a cytokine involved in immune response and inflammation and may be elevated in conditions including infection, autoimmune disorders, cardiovascular disease, and certain cancers.
Service Type: Laboratory diagnostic test — clinical chemistry / immunoassay
Typical Site of Service: Clinical laboratory or hospital laboratory; specimens collected in outpatient clinics, inpatient settings, or specialized testing centers
Clinical & Coding Specifications
Clinical Context
A 62-year-old male admitted to the hospital with fever, progressive shortness of breath, and hypoxemia following recent exposure to COVID-19. The treating team suspects severe systemic inflammation and possible cytokine release contributing to respiratory decline. A serum sample is ordered for measurement of interleukin-6 (IL-6) by immunoassay to quantify inflammatory activity and help guide discussions about immunomodulatory therapy. Venipuncture is performed in the inpatient ward; the specimen is sent to the hospital clinical laboratory. The laboratory receives the sample, logs it into the LIS, performs the IL-6 immunoassay (quantitative), verifies results, and reports a numeric value with the laboratory reference range to the electronic medical record. Ordering clinicians review the IL-6 value in the context of clinical status, other inflammatory markers (CRP, ferritin), microbiology results, and imaging to inform care decisions and document interpretation in progress notes.
Coding Specifications
| Modifier | Description | When to Use |
|---|---|---|
90 | Reference (Outside) Laboratory | When the IL-6 test is performed by an independent outside laboratory and billed by a referring facility/provider. |
91 | Repeat Clinical Diagnostic Lab Test |