Need help choosing the right code?
Ask CasePilot about procedures, modifiers, bundling, and coding guidance.
Try CasePilot© Copyright 2026 American Medical Association. All rights reserved.
The CPT® Code 87400 refers to a laboratory test designed to detect the presence of Influenza A or B antigens in a sample using various immunoassay techniques. These techniques include enzyme immunoassay (EIA), enzyme-linked immunosorbent assay (ELISA), fluorescence immunoassay (FIA), and immunochemiluminometric assay (IMCA). Influenza A and B are viral pathogens responsible for causing influenza, commonly known as the flu, which can lead to a range of symptoms from mild respiratory issues to severe complications such as pneumonia. Influenza A is notable for its ability to infect both humans and animals, including birds and swine, while Influenza B primarily affects humans. The testing process involves obtaining a sample, which may be blood or respiratory secretions, and preparing it for laboratory analysis. The sample is either placed in a fixative or sent fresh to the laboratory. The immunoassay techniques employed in this test are highly sensitive and capable of detecting even minute quantities of the influenza antigen. For instance, EIA and ELISA work by binding the antigen to a specific antibody, followed by the addition of a secondary enzyme-labeled antibody that facilitates detection through a colorimetric reaction. This reaction results in a visible color change, which can be quantitatively assessed. Similarly, FIA utilizes a fluorescent compound to detect the binding of the antibody to the antigen, while IMCA employs chemiluminescent substances to identify and quantify the antigen-antibody complex through light emission. The results of this test can be reported qualitatively or semi-quantitatively, providing valuable information for diagnosing influenza infections.
© Copyright 2026 Coding Ahead. All rights reserved.
The CPT® Code 87400 is indicated for the detection of Influenza A or B antigens in patients presenting with symptoms consistent with influenza infection. The following conditions may warrant the use of this test:
The procedure for conducting the test under CPT® Code 87400 involves several key steps to ensure accurate detection of Influenza A or B antigens:
After the completion of the test, the laboratory will analyze the results and provide a report detailing the presence or absence of Influenza A or B antigens. Healthcare providers will interpret these results in conjunction with the patient's clinical presentation and history. Depending on the findings, further clinical management may be necessary, including treatment options or additional testing. It is important for healthcare professionals to communicate the results to the patient and discuss any required follow-up actions or precautions, especially in cases of confirmed influenza infection.
| Short Descr | INFLUENZA A/B EACH AG IA | Medium Descr | IAAD IA INFLUENZA A/B EACH | Long Descr | Infectious agent antigen detection by immunoassay technique (eg, enzyme immunoassay [EIA], enzyme-linked immunosorbent assay [ELISA], fluorescence immunoassay [FIA], immunochemiluminometric assay [IMCA]), qualitative or semiquantitative; Influenza, A or B, each | 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) | Yes | 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 | 2 | CCS Clinical Classification | 206 - Microscopic examination (bacterial smear, culture, toxicology) |
| QW | Clia waived test | 59 | Distinct procedural service: under certain circumstances, it may be necessary to indicate that a procedure or service was distinct or independent from other non-e/m services performed on the same day. modifier 59 is used to identify procedures/services, other than e/m services, that are not normally reported together, but are appropriate under the circumstances. documentation must support a different session, different procedure or surgery, different site or organ system, separate incision/excision, separate lesion, or separate injury (or area of injury in extensive injuries) not ordinarily encountered or performed on the same day by the same individual. however, when another already established modifier is appropriate it should be used rather than modifier 59. only if no more descriptive modifier is available, and the use of modifier 59 best explains the circumstances, should modifier 59 be used. note: modifier 59 should not be appended to an e/m service. to report a separate and distinct e/m service with a non-e/m service performed on the same date, see modifier 25. | 91 | Repeat clinical diagnostic laboratory test: in the course of treatment of the patient, it may be necessary to repeat the same laboratory test on the same day to obtain subsequent (multiple) test results. under these circumstances, the laboratory test performed can be identified by its usual procedure number and the addition of modifier 91. note: this modifier may not be used when tests are rerun to confirm initial results; due to testing problems with specimens or equipment; or for any other reason when a normal, one-time, reportable result is all that is required. this modifier may not be used when other code(s) describe a series of test results (eg, glucose tolerance tests, evocative/suppression testing). this modifier may only be used for laboratory test(s) performed more than once on the same day on the same patient. | XU | Unusual non-overlapping service, the use of a service that is distinct because it does not overlap usual components of the main service | 26 | Professional component: certain procedures are a combination of a physician or other qualified health care professional component and a technical component. when the physician or other qualified health care professional component is reported separately, the service may be identified by adding modifier 26 to the usual procedure number. | Q6 | Service furnished under a fee-for-time compensation arrangement by a substitute physician or by a substitute physical therapist furnishing outpatient physical therapy services in a health professional shortage area, a medically underserved area, or a rural area | XE | Separate encounter, a service that is distinct because it occurred during a separate encounter | 32 | Mandated services: services related to mandated consultation and/or related services (eg, third party payer, governmental, legislative or regulatory requirement) may be identified by adding modifier 32 to the basic procedure. | 51 | Multiple procedures: when multiple procedures, other than e/m services, physical medicine and rehabilitation services or provision of supplies (eg, vaccines), are performed at the same session by the same individual, the primary procedure or service may be reported as listed. the additional procedure(s) or service(s) may be identified by appending modifier 51 to the additional procedure or service code(s). note: this modifier should not be appended to designated "add-on" codes (see appendix d). | 76 | Repeat procedure or service by same physician or other qualified health care professional: it may be necessary to indicate that a procedure or service was repeated by the same physician or other qualified health care professional subsequent to the original procedure or service. this circumstance may be reported by adding modifier 76 to the repeated procedure or service. note: this modifier should not be appended to an e/m service. | 95 | Synchronous telemedicine service rendered via a real-time interactive audio and video telecommunications system: synchronous telemedicine service is defined as a real-time interaction between a physician or other qualified health care professional and a patient who is located at a distant site from the physician or other qualified health care professional. the totality of the communication of information exchanged between the physician or other qualified health care professional and the patient during the course of the synchronous telemedicine service must be of an amount and nature that would be sufficient to meet the key components and/or requirements of the same service when rendered via a face-to-face interaction. modifier 95 may only be appended to the services listed in appendix p. appendix p is the list of cpt codes for services that are typically performed face-to-face, but may be rendered via a real-time (synchronous) interactive audio and video telecommunications system. | AI | Principal physician of record | AQ | Physician providing a service in an unlisted health professional shortage area (hpsa) | CR | Catastrophe/disaster related | GA | Waiver of liability statement issued as required by payer policy, individual case | GC | This service has been performed in part by a resident under the direction of a teaching physician | GV | Attending physician not employed or paid under arrangement by the patient's hospice provider | GW | Service not related to the hospice patient's terminal condition | KX | Requirements specified in the medical policy have been met | Q4 | Service for ordering/referring physician qualifies as a service exemption | SA | Nurse practitioner rendering service in collaboration with a physician | UD | Medicaid level of care 13, as defined by each state | XP | Separate practitioner, a service that is distinct because it was performed by a different practitioner | XS | Separate structure, a service that is distinct because it was performed on a separate organ/structure |
|
Date
|
Action
|
Notes
|
|---|---|---|
| 2022-01-01 | Changed | First appearance of change in codebook. |
| 2022-01-01 | Note | Grammatical correction. |
| 2021-01-01 | Changed | First appearance of change in CPT® Code Set. |
| 2020-10-06 | Changed | Code changed. |
| 2016-01-01 | Changed | Description Changed |
| 2011-01-01 | Changed | Short description changed. |
| 2007-01-01 | Changed | Code description changed. |
| 2001-01-01 | Added | First appearance in code book in 2001. |
Get instant expert-level medical coding assistance.