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BETA v.3.0

2025 CPT code 86406

Particle agglutination titer, each antibody.

Report one unit of 86406 for each antibody titer performed on a specimen. This code is typically used as a reflex test after a positive 86403 result.

Modifiers may be applicable. Modifier 91 is used for repeat laboratory tests. Modifier 90 indicates that the test was performed by a reference (outside) laboratory.

Medical necessity for 86406 is established when a quantitative measurement of antibody concentration is required following a positive qualitative screening test. The titer test helps in assessing the immune response, confirming a diagnosis, or monitoring disease activity.

The lab analyst performs the technical steps to evaluate the antibody level in the patient's blood after a positive agglutination screen.

IMPORTANT:Use 86403 for the initial particle agglutination screening test. Do not use this code for pregnancy tests (84702, 84703) or rapid plasma reagin tests (86592, 86593).

In simple words: This test measures the amount of a specific antibody in your blood. It's usually done after a different test shows that the antibody is present.The test helps figure out how much of the antibody is in your blood, which can be helpful for checking your immune system or diagnosing certain illnesses.

This code represents a titer test using particle agglutination to determine the concentration of a specific antibody in a specimen. It's typically performed after a positive particle agglutination screening test (86403).The test involves a series of dilutions with varying antigen levels to quantify the antibody concentration.One unit of 86406 is reported for each antibody titer performed.This test is often used to evaluate immune status or check for illnesses caused by specific organisms.

Example 1: A patient has a positive screening test for a specific antibody. A titer test (86406) is then performed to quantify the concentration of the antibody to help assess the patient's immune response or diagnose an infection., A patient with a suspected autoimmune disorder undergoes a series of particle agglutination tests. The titer test (86406) helps determine the level of specific autoantibodies, aiding in diagnosis and disease management., Following exposure to an infectious agent, a patient's blood is tested for specific antibodies. The titer test (86406) measures the antibody concentration to assess the immune response and guide treatment decisions.

Documentation should include the positive screening test result that prompted the titer, the specific antibody being tested, and the medical reason for the test (e.g., suspected infection, autoimmune disorder). The patient's clinical information should support the medical necessity of the titer test.

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