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Official Description

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; hepatitis B surface antigen (HBsAg)

© Copyright 2026 American Medical Association. All rights reserved.

Common Language Description

The CPT® Code 87340 refers to a laboratory test designed to detect the presence of Hepatitis B surface antigen (HBsAg) in serum or plasma. This test employs various immunoassay techniques, including enzyme immunoassay (EIA), enzyme-linked immunosorbent assay (ELISA), fluorescence immunoassay (FIA), and immunochemiluminometric assay (IMCA). The detection of HBsAg is crucial as it indicates an active Hepatitis B virus (HBV) infection, which can lead to serious liver complications such as cirrhosis and hepatocellular carcinoma. The test can be performed qualitatively, providing a simple positive or negative result, or semiquantitatively, offering a measure of the antigen concentration. In the context of Hepatitis B, the presence of HBsAg signifies that the virus is present in the bloodstream, while the HBeAg test, which is related but distinct, is utilized to monitor the activity of the infection and the effectiveness of treatment. The HBsAg neutralization test serves as a confirmatory test for positive HBsAg results. Hepatitis B can be transmitted through blood and body fluids, and symptoms may include fever, fatigue, abdominal pain, and nausea, although some individuals may remain asymptomatic. The laboratory procedure involves obtaining a serum or plasma sample, which is then processed using the aforementioned immunoassay techniques to detect the antigen's presence through specific reactions that produce measurable signals, such as color changes or fluorescence.

© Copyright 2026 Coding Ahead. All rights reserved.

1. Indications

The procedure associated with CPT® Code 87340 is indicated for the detection of Hepatitis B surface antigen (HBsAg) in patients who may be at risk for Hepatitis B virus (HBV) infection. The following conditions warrant the performance of this test:

  • Screening for Hepatitis B Infection Individuals who are at risk for HBV infection, including those with a history of intravenous drug use, unprotected sexual contact with infected individuals, or exposure to contaminated blood products.
  • Monitoring of Chronic Hepatitis B Patients diagnosed with chronic Hepatitis B infection require regular monitoring of HBsAg levels to assess viral activity and the need for treatment.
  • Assessment of Liver Health Individuals presenting with symptoms suggestive of liver disease, such as jaundice, abdominal pain, or unexplained fatigue, may be tested for HBsAg to determine the underlying cause.

2. Procedure

The procedure for CPT® Code 87340 involves several key steps to ensure accurate detection of HBsAg in serum or plasma samples. The following procedural steps are outlined:

  • Sample Collection A serum or plasma sample is obtained from the patient, typically through venipuncture. The sample is collected in a sterile container and may be placed in a fixative or sent fresh to the laboratory for processing.
  • Preparation of the Sample Once received in the laboratory, the sample is prepared for testing. This may involve centrifugation to separate the serum or plasma from cellular components, ensuring that the sample is suitable for immunoassay techniques.
  • Immunoassay Technique Application The prepared sample is subjected to one of the immunoassay techniques, such as EIA, ELISA, FIA, or IMCA. Each technique utilizes specific antibodies that bind to HBsAg if present in the sample.
  • Detection and Measurement The presence of HBsAg is detected through a chromogenic reaction or fluorescence, depending on the technique used. For EIA and ELISA, a secondary enzyme-labeled antibody is added, producing a color change that can be quantitatively measured. In FIA, a fluorescent compound is used, while IMCA relies on chemiluminescent reactions to quantify the antigen-antibody complex.
  • Result Interpretation The results are interpreted based on the colorimetric readings or fluorescence intensity, indicating whether HBsAg is present and, if applicable, the concentration of the antigen in the sample.

3. Post-Procedure

After the procedure associated with CPT® Code 87340, the laboratory will analyze the results and report them to the requesting healthcare provider. If HBsAg is detected, further evaluation may be necessary to determine the stage of the infection and appropriate management strategies. Patients may be advised to follow up with their healthcare provider to discuss the results and any potential implications for treatment or lifestyle modifications. Additionally, if the test is positive, further testing, such as the HBeAg test or HBsAg neutralization test, may be recommended to assess the level of viral replication and the need for antiviral therapy. It is important for patients to understand the significance of their results and to engage in discussions regarding their health and any necessary precautions to prevent transmission of the virus.

Short Descr HEPATITIS B SURFACE AG IA
Medium Descr IAAD IA HEPATITIS B SURFACE ANTIGEN
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; hepatitis B surface antigen (HBsAg)
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 1
CCS Clinical Classification 206 - Microscopic examination (bacterial smear, culture, toxicology)
GZ Item or service expected to be denied as not reasonable and necessary
90 Reference (outside) laboratory: when laboratory procedures are performed by a party other than the treating or reporting physician or other qualified health care professional, the procedure may be identified by adding modifier 90 to the usual procedure number.
GA Waiver of liability statement issued as required by payer policy, individual case
33 Preventive services: when the primary purpose of the service is the delivery of an evidence based service in accordance with a us preventive services task force a or b rating in effect and other preventive services identified in preventive services mandates (legislative or regulatory), the service may be identified by adding 33 to the procedure. for separately reported services specifically identified as preventive, the modifier should not be used.
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.
GY Item or service statutorily excluded, does not meet the definition of any medicare benefit or, for non-medicare insurers, is not a contract benefit
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.
77 Repeat procedure by another physician or other qualified health care professional: it may be necessary to indicate that a basic procedure or service was repeated by another physician or other qualified health care professional subsequent to the original procedure or service. this circumstance may be reported by adding modifier 77 to the repeated procedure or service. note: this modifier should not be appended to an e/m service.
Q4 Service for ordering/referring physician qualifies as a service exemption
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.
Q1 Routine clinical service provided in a clinical research study that is in an approved clinical research study
AY Item or service furnished to an esrd patient that is not for the treatment of esrd
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.
CC Procedure code change (use 'cc' when the procedure code submitted was changed either for administrative reasons or because an incorrect code was filed)
CR Catastrophe/disaster related
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
GX Notice of liability issued, voluntary under payer policy
KX Requirements specified in the medical policy have been met
PD Diagnostic or related non diagnostic item or service provided in a wholly owned or operated entity to a patient who is admitted as an inpatient within 3 days
Q0 Investigational clinical service provided in a clinical research study that is in an approved clinical research study
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
X5 Diagnostic services requested by another clinician: for reporting services by a clinician who furnishes care to the patient only as requested by another clinician or subsequent and related services requested by another clinician; this modifier is reported for patient relationships that may not be adequately captured by the above alternative categories; reporting clinician service examples include but are not limited to, the radiologist's interpretation of an imaging study requested by another clinician
XS Separate structure, a service that is distinct because it was performed on a separate organ/structure
XU Unusual non-overlapping service, the use of a service that is distinct because it does not overlap usual components of the main service
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.
1998-01-01 Added First appearance in code book in 1998.
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