82784

Gammaglobulin (immunoglobulin); IgA, IgD, IgG, IgM, each

CPT code 82784 represents the laboratory test for the quantitative measurement of a specific class of gammaglobulin (immunoglobulins), which includes IgA, IgD, IgG, or IgM, in serum or other body fluids. Immunoglobulins are essential antibodies produced by plasma cells that play a critical role in the immune system by recognizing and binding to specific antigens, such as bacteria, viruses, and other pathogens. This quantitative assay is crucial for diagnosing, assessing, and monitoring a wide variety of immunological and hematological disorders. Common clinical applications include the evaluation of primary and secondary immunodeficiencies, autoimmune diseases, chronic infections, multiple myeloma, macroglobulinemia, and other plasma cell dyscrasias. The procedure begins with the collection of a patient specimen, usually a venous blood sample, which is processed in the laboratory to extract the serum. The serum is then analyzed using advanced immunoassay methodologies, predominantly automated nephelometry or turbidimetry, to accurately quantify the concentration of the specific immunoglobulin class requested by the ordering physician. It is critical to note that the CPT descriptor specifies 'each' for this code. Therefore, the code is applied per individual immunoglobulin class measured. If a clinician orders a quantitative panel for IgA, IgG, and IgM concurrently to evaluate a patient's overall humoral immune status, CPT code 82784 must be reported three times to accurately reflect the three separate assays performed. The quantitative results help healthcare providers assess the patient's immune competence, evaluate for potential monoclonal gammopathies, and guide targeted therapeutic interventions, such as initiating immunoglobulin replacement therapy or prescribing immunosuppressive treatments.

Clinical Indications

  • Evaluation of suspected primary immunodeficiency disorders, such as Common Variable Immunodeficiency (CVID) or X-linked agammaglobulinemia.
  • Assessment of secondary immunodeficiencies due to conditions like protein-losing enteropathy, nephrotic syndrome, or immunosuppressive therapy.
  • Diagnosis, staging, and monitoring of multiple myeloma, Waldenstrom's macroglobulinemia, and other plasma cell neoplasms.
  • Investigation of patients presenting with recurrent, severe, or atypical bacterial or viral infections.
  • Monitoring the efficacy and adjusting dosing of immunoglobulin replacement therapies (e.g., Intravenous Immunoglobulin [IVIG] or Subcutaneous Immunoglobulin [SCIG]).
  • Evaluation of chronic liver diseases, such as autoimmune hepatitis or primary biliary cholangitis, which may feature elevated immunoglobulins.
  • Assessment of autoimmune diseases, including systemic lupus erythematosus (SLE) or rheumatoid arthritis.

Procedure Steps

  1. Order verification: The clinical laboratory receives and verifies the physician's order specifying which exact immunoglobulin class(es) (IgA, IgD, IgG, or IgM) need to be quantified.
  2. Sample collection: A phlebotomist performs a standard venipuncture to collect a blood sample from the patient into an appropriate serum separator tube or plain red-top tube.
  3. Sample processing: The collected blood sample is centrifuged in the laboratory to separate the serum from the red blood cells and other cellular components.
  4. Reagent preparation: The laboratory scientist or technician prepares the specific antisera and reagents (e.g., anti-IgG or anti-IgA antibodies) required for the precise immunoassay.
  5. Analysis: The patient's serum sample is introduced into an automated clinical chemistry analyzer employing nephelometry, turbidimetry, or radial immunodiffusion techniques.
  6. Quantification: The automated analyzer measures light scattering or absorbance caused by antigen-antibody complexes to calculate the precise concentration of the targeted immunoglobulin class.
  7. Result validation: A qualified laboratory professional reviews the raw analytical data against established reference intervals, calibration curves, and internal quality control standards.
  8. Reporting: The final quantitative results for each requested immunoglobulin class are documented and securely transmitted to the ordering clinician's electronic health record.

Coding Guidelines

  • CPT code 82784 must be reported individually for each specific immunoglobulin class (IgA, IgD, IgG, or IgM) that is tested. For example, an order for IgG, IgA, and IgM requires billing 82784 three times.
  • When billing multiple units of 82784 on the same date of service, follow specific payer policies; some may require the use of modifier 59 (Distinct Procedural Service) or 91 (Repeat Clinical Diagnostic Laboratory Test), while others accept multiple units on a single claim line.
  • Do not use CPT code 82784 for the measurement of Immunoglobulin E (IgE). The quantitative measurement of IgE should be reported using the specific CPT code 82785.
  • If the physician orders testing for specific subclasses of IgG (e.g., IgG1, IgG2, IgG3, IgG4), CPT code 82787 (Gammaglobulin; immunoglobulin subclasses, each) must be used instead of or in addition to 82784.
  • Ensure that the medical record includes clear documentation establishing the medical necessity for each individual immunoglobulin class ordered, linking it to the appropriate ICD-10-CM diagnosis code.

Associated ICD-10 Codes