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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) neutralization

© Copyright 2026 American Medical Association. All rights reserved.

Common Language Description

The CPT® Code 87341 refers to a laboratory test that is specifically designed to detect the presence of Hepatitis B surface antigen (HBsAg) through various immunoassay techniques. This test is crucial for diagnosing and confirming Hepatitis B infections, particularly when a previous HBsAg test has yielded a positive result. The HBsAg neutralization test is a qualitative or semiquantitative assay that can utilize methods such as enzyme immunoassay (EIA), enzyme-linked immunosorbent assay (ELISA), fluorescence immunoassay (FIA), or immunochemiluminometric assay (IMCA). These techniques are adept at identifying very small quantities of the antigen in serum or plasma samples. Hepatitis B is a viral infection that primarily affects the liver and can lead to serious health complications, including cirrhosis and hepatocellular carcinoma, especially in individuals with chronic infections. The virus is transmitted through blood and body fluids, making it a significant public health concern. Symptoms of Hepatitis B can vary widely, ranging from mild to severe, and may include fever, fatigue, abdominal pain, weight loss, nausea, vomiting, and joint pain. In some cases, individuals may remain asymptomatic, which complicates the detection and management of the disease. The testing process involves obtaining a serum or plasma sample, which is then processed in a laboratory setting. The immunoassay techniques employed in this test work by detecting the binding of specific antibodies to the HBsAg, resulting in a measurable color change or fluorescence that indicates the presence of the antigen. This detailed understanding of the procedure and its implications is essential for medical coders and healthcare professionals involved in the diagnosis and treatment of Hepatitis B infections.

© Copyright 2026 Coding Ahead. All rights reserved.

1. Indications

The HBsAg neutralization test (CPT® Code 87341) is indicated for the following conditions:

  • Confirmation of Positive HBsAg Test: This test is performed to confirm the presence of Hepatitis B surface antigen in patients who have previously tested positive for HBsAg.
  • Monitoring Active Hepatitis B Infection: The test is utilized to monitor patients with active Hepatitis B viral (HBV) infections, particularly in assessing the response to therapy.
  • Assessment of Viral Replication: The presence of HBeAg, which can be detected alongside HBsAg, indicates active HBV replication, thus providing critical information regarding the infectivity of the virus.

2. Procedure

The procedure for conducting the HBsAg neutralization test involves several key steps:

  • Sample Collection: A serum or plasma sample is obtained from the patient. This sample is either placed in a fixative or sent fresh to the laboratory for processing. Proper handling and transportation of the sample are crucial to ensure accurate test results.
  • Immunoassay Technique Selection: The laboratory technician selects an appropriate immunoassay technique for the test, which may include enzyme immunoassay (EIA), enzyme-linked immunosorbent assay (ELISA), fluorescence immunoassay (FIA), or immunochemiluminometric assay (IMCA). Each of these techniques is designed to detect the HBsAg in the sample.
  • Antigen-Antibody Reaction: The selected immunoassay technique involves adding a secondary, enzyme-labeled antibody to the sample. This antibody binds to the HBsAg if present, forming an antigen-antibody complex.
  • Detection of Bound Antigen: A chromogenic reaction occurs, producing a visible color change or fluorescence, which indicates the presence of the antigen. In the case of FIA, a fluorescent compound is used to detect the binding of the detection antibody with the analyte molecule.
  • Quantification and Interpretation: The results are assessed qualitatively or semi-quantitatively through colorimetric reading or fluorescence measurement, providing information on the presence and concentration of HBsAg in the sample.

3. Post-Procedure

After the HBsAg neutralization test is completed, the laboratory will analyze the results and report them to the healthcare provider. The interpretation of the results is critical for determining the patient's infection status and guiding further management. If the test confirms the presence of HBsAg, additional follow-up tests may be necessary to assess the extent of the infection and the appropriate treatment options. Patients may be monitored for symptoms and liver function as part of their ongoing care. It is essential for healthcare providers to communicate the results effectively to patients and discuss any necessary next steps in their treatment plan.

Short Descr HEP B SURFACE AG NEUTRLZJ IA
Medium Descr IAAD IA HEPATITIS B SURFACE AG NEUTRALIZATION
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) neutralization
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)
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.
GZ Item or service expected to be denied as not reasonable and necessary
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.
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.
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.
GA Waiver of liability statement issued as required by payer policy, individual case
GW Service not related to the hospice patient's terminal condition
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
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.
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