Summary & Overview
CPT 0312U: Avise® Lupus Proprietary Laboratory Assay
CPT code 0312U designates a Proprietary Laboratory Analyses (PLA) test — Avise® Lupus from Exagen, Inc. — that measures ten biomarkers, including eight IgG autoantibodies and two cell–bound complement activation products (CB–CAPs), to support the differential diagnosis of systemic lupus erythematosus (SLE). As a PLA code, 0312U applies only to this single manufacturer’s assay, reflecting the growing role of proprietary molecular diagnostics in autoimmune disease evaluation. Nationwide relevance stems from the clinical need for improved SLE diagnostic specificity and the policy implications of single-source lab codes for coverage and coding consistency.
Key payers covered in this analysis include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find an overview of clinical context for the Avise® Lupus assay, typical sites of service, and the practical implications of a PLA-designated CPT code. The publication outlines coverage considerations across major national payers, common billing modifiers, and areas where payers commonly request supporting documentation. It also summarizes benchmarks and policy updates relevant to proprietary laboratory codes, and provides clarity on how 0312U fits into laboratory service lines and diagnostic workflows for suspected SLE.
Billing Code Overview
CPT code 0312U is a Proprietary Laboratory Analyses (PLA) code reported exclusively for the Avise® Lupus test developed by Exagen, Inc. The test uses a specimen such as serum, plasma, or whole blood to measure a panel of 10 biomarkers — eight IgG autoantibodies associated with systemic lupus erythematosus (SLE) and two cell–bound complement activation products (CB–CAPs) — to aid in the differential diagnosis of SLE. CB–CAPs are traces of cell-surface proteins activated as part of the complement immune system.
Service type: Proprietary laboratory diagnostic assay
Typical site of service: Clinical laboratory or hospital laboratory, with specimens collected in outpatient clinics or phlebotomy centers
Clinical & Coding Specifications
Clinical Context
A 34-year-old woman presents to a rheumatology clinic with persistent arthralgia, photosensitivity, intermittent oral ulcers, and a history of unexplained cytopenias. Initial screening tests (ANA, anti-dsDNA, complement levels) are equivocal. The rheumatologist orders 0312U (Avise® Lupus) using a serum specimen to measure eight IgG autoantibodies and two cell-bound complement activation products (CB–CAPs) to aid in the differential diagnosis of systemic lupus erythematosus (SLE). The clinical workflow: the patient has blood drawn in clinic or at an outpatient laboratory, the specimen is sent to the manufacturer’s laboratory for the proprietary assay, and results are returned to the ordering provider. Results are used in conjunction with clinical findings and other laboratory studies to support or refute an SLE diagnosis, inform additional testing, and guide follow-up planning.
Coding Specifications
| Modifier | Description | When to Use |
|---|---|---|
00 | No modifier — standard reporting | Use when no special circumstances apply to the laboratory service |
26 | Professional component |