Summary & Overview
CPT 86329: Immunodiffusion Assay for Immunoglobulins
CPT code 86329 represents an immunodiffusion assay to evaluate the amounts and types of immunoglobulins (antibodies) in a patient sample. This laboratory procedure is used to characterize immune responses and detect abnormal immunoglobulin patterns that can inform diagnosis and monitoring of infections, immunodeficiencies, and certain hematologic disorders. Nationally, accurate coding for specialized immunology tests like 86329 matters for clinical documentation, lab billing integrity, and appropriate utilization tracking across health systems.
Key payers covered in this analysis include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a concise overview of the clinical context for the test, typical sites of service, and the types of benchmarks and policy considerations that commonly accompany specialized laboratory codes. The publication outlines expected content such as coverage and reimbursement benchmarks, coding guidance and common modifiers, and policy updates that affect lab services. It also situates the code in clinical practice by describing when immunodiffusion testing is ordered and its relevance to diagnosis and monitoring.
Data not available in the input is noted where payer-specific rates, taxonomies, ICD-10 pairings, and related codes would normally appear.
Billing Code Overview
CPT code 86329 describes an immunodiffusion laboratory procedure used to evaluate a patient sample for the amounts and types of immunoglobulins (antibodies). The test assesses the presence and relative concentrations of specific immunoglobulin types produced by the immune system to respond to infections or other immune stimuli.
Service type: Specialty clinical laboratory immunology testing. Typical site of service: Clinical laboratory or hospital laboratory (specimen collected in outpatient clinic or hospital and analyzed in the lab).
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Clinical & Coding Specifications
Clinical Context
A 47-year-old patient with a history of recurrent respiratory infections and unexplained hypogammaglobulinemia is referred to the clinical laboratory for protein immunodiagnostic testing. The ordering clinician suspects a quantitative and qualitative abnormality of immunoglobulins (IgG, IgA, IgM) and requests immunodiffusion to characterize immunoglobulin types and relative concentrations. Blood is drawn via standard venipuncture; the specimen is labeled and transported to the immunology laboratory. A clinical laboratory scientist or immunology technologist performs 86329 (immunodiffusion, not elsewhere specified) using agarose or polyacrylamide gel techniques to separate and visualize immunoglobulin precipitin lines. Results are reviewed by the laboratory director or pathologist and reported to the ordering clinician for correlation with serum protein electrophoresis, clinical findings, and possible further testing (e.g., immunofixation, quantitative immunoglobulin assays). Typical sites of service include hospital outpatient laboratories, independent clinical reference laboratories, and hospital inpatient laboratories. The service type is a clinical laboratory immunology procedure performed by trained lab personnel under CLIA-certified conditions.
Coding Specifications
- Modifier and taxonomy guidance below applies to
86329performed in clinical laboratory settings. Use only clinically appropriate modifiers per payer rules.
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