Coding Ahead
CasePilot
Medical Coding Assistant
Case2Code
Search and Code Lookup Tool
CareerCenter
Medical Coding Job Board
Log in Register free account

Need help choosing the right code?

Ask CasePilot about procedures, modifiers, bundling, and coding guidance.

Try CasePilot
Code deleted, see 87301-87451, 87802-87899

Official Description

Infectious agent antigen detection by immunoassay technique, (eg, enzyme immunoassay [EIA], enzyme-linked immunosorbent assay [ELISA], immunochemiluminometric assay [IMCA]), qualitative or semiquantitative; single step method, not otherwise specified, each organism

© Copyright 2026 American Medical Association. All rights reserved.

Common Language Description

The CPT® Code 87450 refers to a laboratory test designed to detect infectious agent antigens in blood and other body fluids through the use of immunoassay techniques. This code encompasses various methodologies, including enzyme immunoassay (EIA), enzyme-linked immunosorbent assay (ELISA), and immunochemiluminometric assay (IMCA). These techniques are pivotal in clinical diagnostics as they utilize labeled antibodies to identify specific antigens present in patient samples. The EIA and ELISA methods are particularly sensitive, capable of detecting minute quantities of antigens due to the incorporation of a secondary enzyme-labeled antibody. This enzyme catalyzes a reaction that results in a color change or fluorescence, allowing for qualitative or semiquantitative assessment of the infectious agent's presence. On the other hand, IMCA employs a light emission device to quantify the antigen-antibody complex, providing a more precise measurement of the infectious agent. The testing can be performed using a single-step method, where the labeled antibody is added to the sample, followed by a wash and examination, or a multi-step method that involves several washes and additional labeled antibodies. It is important to note that this code specifically applies to the single-step method for each organism that is not otherwise specified (NOS), distinguishing it from other related codes that may involve multi-step methods or multiple organisms.

© Copyright 2026 Coding Ahead. All rights reserved.

1. Indications

The CPT® Code 87450 is indicated for use in the detection of infectious agent antigens in various clinical scenarios. The following conditions may warrant the use of this test:

  • Infectious Disease Diagnosis This test is utilized to identify specific infectious agents in patients presenting with symptoms of infection.
  • Monitoring Treatment Efficacy It can be employed to assess the effectiveness of ongoing treatment for infections by measuring antigen levels.
  • Screening for Infectious Agents The test may be used as a screening tool in populations at risk for certain infectious diseases.

2. Procedure

The procedure for CPT® Code 87450 involves several key steps to ensure accurate detection of infectious agent antigens:

  • Sample Collection A sample of blood or other body fluid is collected from the patient, which will be tested for the presence of infectious antigens.
  • Preparation of the Sample The collected sample is prepared for testing, which may involve dilution or other preparatory steps to optimize the assay conditions.
  • Application of Labeled Antibody A labeled antibody specific to the target antigen is added to the sample. This antibody will bind to any infectious agent antigens present.
  • Washing Step The sample is washed to remove unbound antibodies, ensuring that only the antigen-antibody complexes remain for detection.
  • Detection of Antigen The presence of the antigen is detected through a chromogenic reaction or fluorescence, depending on the method used (EIA, ELISA, or IMCA). This step allows for qualitative or semiquantitative measurement of the infectious agent.

3. Post-Procedure

After the procedure associated with CPT® Code 87450, the laboratory will analyze the results and report the findings. The expected outcome is a qualitative or semiquantitative result indicating the presence or absence of the infectious agent antigen. Clinicians may use these results to guide further diagnostic or therapeutic decisions. It is essential for healthcare providers to interpret the results in conjunction with clinical findings and other diagnostic tests. Additionally, any necessary follow-up testing or treatment adjustments should be discussed with the patient based on the results obtained from this immunoassay technique.

Short Descr AG DETECT NOS IA SINGLE
Medium Descr IAAD IA SINGLE STEP METHOD NOS EA ORGANISM
Long Descr Infectious agent antigen detection by immunoassay technique, (eg, enzyme immunoassay [EIA], enzyme-linked immunosorbent assay [ELISA], immunochemiluminometric assay [IMCA]), qualitative or semiquantitative; single step method, not otherwise specified, each organism
Status Code Statutory Exclusion (from MPFS, may be paid under other methodologies)
Global Days XXX - Global Concept Does Not Apply
PC/TC Indicator (26, TC) 9 - Not Applicable
Multiple Procedures (51) 9 - Concept does not apply.
Bilateral Surgery (50) 9 - Concept does not apply.
Physician Supervisions 09 - Concept does not apply.
Assistant Surgeon (80, 82) 9 - Concept does not apply.
Co-Surgeons (62) 9 - Concept does not apply.
Team Surgery (66) 9 - Concept does not apply.
Diagnostic Imaging Family 99 - Concept Does Not Apply
CLIA Waived (QW) No
APC Status Indicator Conditionally packaged laboratory tests
Type of Service (TOS) 5 - Diagnostic Laboratory
Berenson-Eggers TOS (BETOS) T1H - Lab tests - other (non-Medicare fee schedule)
MUE Not applicable/unspecified.
CCS Clinical Classification 206 - Microscopic examination (bacterial smear, culture, toxicology)
Date
Action
Notes
2022-01-01 Deleted First appearance of deletion in codebook.
2021-01-01 Deleted First appearance of deletion in CPT® Code Set.
2021-01-01 Changed Code description changed.
2020-10-05 Deleted Code deleted.
2020-10-01 Deleted Code deleted, see 87301-87451, 87802-87899
2016-01-01 Changed Description Changed
2011-01-01 Changed Short description changed.
2001-01-01 Changed Code description changed.
1998-01-01 Added First appearance in code book in 1998.
Code
Description
CasePilot

Get instant expert-level medical coding assistance.

Ask about:
CPT Codes Guidelines Modifiers Crosswalks NCCI Edits Compliance Medicare Coverage
Example: "What is CPT code 99213?" or "Guidelines for E/M services"