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A quantitative immunoassay is a laboratory procedure designed to measure the concentration of a specific chemical substance, known as an analyte, in a biological sample. This type of testing is distinct in that it focuses on substances other than antibodies or antigens that the body produces in response to infectious agents. The term "immunoassay" refers to a variety of techniques that utilize the principles of immunology to detect and quantify substances. In this context, the analytes being measured can be associated with a wide range of non-infectious diseases and disorders, such as myasthenia gravis, pancreatic disease, and parathyroid disease, among others. Quantitative testing is crucial as it provides precise measurements of the levels of these substances, which can be critical for diagnosis, monitoring, and treatment decisions. The results of these tests can help healthcare providers understand the underlying conditions affecting a patient. For instance, specific substances that may be evaluated using this code include neuronal antibodies, cytokines, and vascular endothelial growth factor, which are important in various clinical scenarios. It is important to note that while this code encompasses a broad range of quantitative immunoassays, it specifically excludes tests that utilize the radioimmunoassay (RIA) method. RIA is a specialized technique that employs radioisotope-labeled antigens to detect minute quantities of substances, and it is reported under a different code (CPT® Code 83519). When using CPT® Code 83520, it is essential to report each analyte tested separately, as multiple tests for different substances will require multiple submissions of this code. This structured approach ensures accurate billing and documentation for the laboratory services provided.
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The quantitative immunoassay represented by CPT® Code 83520 is indicated for the detection and measurement of various chemical substances (analytes) that are not related to infectious agents. The following conditions and diseases may warrant the use of this testing method:
The procedure for conducting a quantitative immunoassay using CPT® Code 83520 involves several key steps, which are outlined as follows:
Post-procedure care following a quantitative immunoassay using CPT® Code 83520 typically involves the interpretation of results by the healthcare provider. The provider will review the quantitative data obtained from the test to assess the patient's condition and determine any necessary follow-up actions. Depending on the results, further testing or treatment may be indicated. It is also essential for the laboratory to ensure proper documentation of the test results and any relevant clinical information to support ongoing patient care and compliance with billing requirements.
| Short Descr | IMMUNOASSAY QUANT NOS NONAB | Medium Descr | IMMUNOASSAY ANALYTE QUANTITATIVE NOS | Long Descr | Immunoassay for analyte other than infectious agent antibody or infectious agent antigen; quantitative, not otherwise specified | 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 | 9 | CCS Clinical Classification | 233 - Laboratory - Chemistry and Hematology |
| 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. | 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. | 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. | XU | Unusual non-overlapping service, the use of a service that is distinct because it does not overlap usual components of the main service | 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 | GA | Waiver of liability statement issued as required by payer policy, individual case | Q1 | Routine clinical service provided in a clinical research study that is in an approved clinical research study | Q4 | Service for ordering/referring physician qualifies as a service exemption | 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. | 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. | GZ | Item or service expected to be denied as not reasonable and necessary | RT | Right side (used to identify procedures performed on the right side of the body) | GW | Service not related to the hospice patient's terminal condition | XS | Separate structure, a service that is distinct because it was performed on a separate organ/structure | 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. | AY | Item or service furnished to an esrd patient that is not for the treatment of esrd | CC | Procedure code change (use 'cc' when the procedure code submitted was changed either for administrative reasons or because an incorrect code was filed) | 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 | GX | Notice of liability issued, voluntary under payer policy | LT | Left side (used to identify procedures performed on the left side of the body) | PO | Excepted service provided at an off-campus, outpatient, provider-based department of a hospital | Q3 | Live kidney donor surgery and related services | 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 | QW | Clia waived test | 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 | XE | Separate encounter, a service that is distinct because it occurred during a separate encounter | XP | Separate practitioner, a service that is distinct because it was performed by a different practitioner |
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Action
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Notes
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| 2024-01-01 | Changed | Guideline information changed. |
| 2011-01-01 | Changed | Short description changed. |
| 2010-01-01 | Changed | Code description changed. |
| 1993-01-01 | Added | First appearance in code book in 1993. |
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