Esoteric Testing Market Segments

Esoteric Testing Market Segments

The esoteric testing market segments can be seen in their simplest form in two areas:

  1. chemiluminescence immunoassay
  2. enzyme-linked immunosorbent assay radioimmunoassay, mass spectrometry, flow cytometry, real-time PCR (qPCR), and other technical modalities of testing.

Because these tests are performed differently than in a routine medical laboratory, esoteric testing is most likely to be performed instead by a reference laboratory.  “Sending out” for such tests where specialized knowledge and techniques are required is expected in the healthcare industry.  According to our data analytics, these tests are sent to reference laboratories 100 percent of the time and should be billed with CPT code modifier 90.

Chemiluminescence Immunoassay Esoteric Tests

A quantitative immunoassay is performed to detect a chemical substance (analyte) other than an antigen or antibody which is produced by the body in response to an infectious agent. There are many immunoassays for non-infectious antigens and antibodies that are reported with these codes.  There are also non-infectious diseases that may be tested using this approach.  These include:

  • myasthenia gravis (with or without acute exacerbation) using ICD-10 CM code G70.00 or G70.01.
  • Also, pancreatic disease (precision is essential to test for and accurately use the results of an esoteric test because there are over 300 potential ICD-10 diagnosis codes associated with some form of pancreatic disease, including alcohol-induced chronic pancreatitis ICD-10 K86.8 and K86.1, which is a non-specific code ‘other chronic pancreatitis’);
  • parathyroid disease (again there are over 300 potential codes, so specificity is essential).

Examples of specific substances reported with these codes include neuronal antibodies, cytokine production, and vascular endothelial growth factor.   Chemiluminescence Immunoassay Esoteric Tests – Radioimmunoassay (RIA)

Quantitative testing measures the exact amount or level of the substance in the test sample. Generally, it is recommended that providers use CPT code 83519 for the quantitative radioimmunoassay (RIA) testing method. RIA uses radioisotope labeled antigens or other radioisotope labeled substances along with unlabeled substances to bind the specific antigen or substance being tested. The binding of the importance to the radiolabeled antigen or other substance allows the substance to be measured (quantified). RIA enables the measurement of minute quantities of enzymes, hormones, or other substances.

Chemiluminescence Immunoassay Esoteric Tests – Non-Radioimmunoassay (RIA)

For other technologies such as mass spectrometry, flow cytometry, real-time PCR (qPCR), it is recommended that providers bill CPT 83520 for quantitative testing methods other than radioimmunoassay. Codes are reported for each substance class, or subclass tested using this technique.  For example, when testing for interleukin 4, 5, 10, and 13 by multi-analyte fluorescence detection, CPT 83520 would be reported four times.   The CSS clinical classification is 233 – Laboratory – Chemistry and Hematology for this code

Enzyme-linked immunosorbent assay esoteric tests

According to the American Medical Association, June 2020 CPT Editorial Panel news, the CPT code 87426 was approved:

87426 severe acute respiratory syndrome coronavirus (e.g., SARS-CoV, SARS-CoV-2 ) The new codes will allow for more accurate reporting of immunoassay testing for SARS-Coronavirus antigen. It is worth noting that the code is not specific for SARS-CoV-2, and it could be used for an immunoassay that detects antigenic proteins for either SARS-CoV or SARS-CoV-2. As the antigenic proteins across the SARS-Coronavirus family are highly conserved, the assays currently available are not capable of distinguishing between SARS-CoV and SARS-CoV-2.



CPT code 87301 Infectious agent antigen detection by immunoassay technique, (e.g., enzyme immunoassay , enzyme-linked immunosorbent assay , immunochemiluminometric assay ) qualitative or semiquantitative, multiple-step method; adenovirus enteric types 40/41.  The CSS clinical classification is 206 – Microscopic examination (bacterial smear, culture, toxicology).

PCRELISA combines an immunological method (ELISA) to detect and quantify specific PCR products directly after immobilization of DNA on a microtiter plate. PCRELISA is also less commonly known as PCR-ELOSA (polymerase chain reaction-enzyme-linked oligosorbent assay).  See Sue MJ, Yeap SK, Omar AR, Tan SW. Application of PCR-ELISA in molecular diagnosis. Biomed Res Int. 2014;2014:653014. doi: 10.1155/2014/653014. Epub 2014 May 27. PMID: 24971343; PMCID: PMC4058250.

Myasthenia gravis is an autoimmune disease that primarily causes weakness in the voluntary muscles (e.g., eye movement, facial expressions, swallowing). Weakness worsens with activity and improves with rest. It is caused when the body’s immune system makes antibodies that block or change some of the nerve signals to these muscles. Symptoms may go into periods of remission which may be temporary or permanent.

Medicare Local Coverage Determinations (Medicare LCDs) are not published that are specific to these codes at this time however Medicare’s standard guidance regarding whether tests are medically necessary and that the patient / beneficiary clinical documentation is adequate to support the need for testing applies.  Commercial payer medical policies are evolving as well as the time that this was published.  Like the other codes above, berenson-eggers tos (betos) lists the code clinical category as ‘other non-Medicare.’ The BETOS coding system was developed for analyzing Medicare expenditures. The coding system covers HCPCS codes; assigns a HCPCS code to only one BETOS code; consists of clinical categories


Michael F. Arrigo

Michael is Managing Partner & CEO of No World Borders, a leading healthcare management and IT consulting firm. He serves as an expert witness in Federal and State Court and was recently ruled as an expert by a 9th Circuit Federal Judge. He serves as a patent expert witness on intellectual property disputes, both as a Technical Expert and a Damages expert. His vision for the firm is to continue acquisition of skills and technology that support the intersection of clinical data and administrative health data where the eligibility for medically necessary care is determined. He leads a team that provides litigation consulting as well as advisory regarding medical coding, medical billing, medical bill review and HIPAA Privacy and Security best practices for healthcare clients, Meaningful Use of Electronic Health Records. He advises legal teams as an expert witness in HIPAA Privacy and Security, medical coding and billing and usual and customary cost of care, the Affordable Care Act and benefits enrollment, white collar crime, False Claims Act, Anti-Kickback, Stark Law, physician compensation, Insurance bad faith, payor-provider disputes, ERISA plan-third-party administrator disputes, third-party liability, and the Medicare Secondary Payer Act (MSPA) MMSEA Section 111 reporting. He uses these skills in disputes regarding the valuation of pharmaceuticals and drug costs and in the review and audit of pain management and opioid prescribers under state Standards and the Controlled Substances Act. He consults to venture capital and private equity firms on mHealth, Cloud Computing in Healthcare, and Software as a Service. He advises ERISA self-insured employers on cost of care and regulations. Arrigo was recently retained by the U.S. Department of Justice (DOJ) regarding a significant false claims act investigation. He has provided opinions on over $1 billion in health care claims and due diligence on over $8 billion in healthcare mergers and acquisitions. Education: UC Irvine - Economics and Computer Science, University of Southern California - Business, studies at Stanford Medical School - Biomedical Informatics, studies at Harvard Medical School - Bioethics. Trained in over 10 medical specialties in medical billing and coding. Trained by U.S. Patent and Trademark Office (USPTO) and PTAB Judges on patent statutes, rules and case law (as a non-attorney to better advise clients on Technical and Damages aspects of patent construction and claims). Mr. Arrigo has been interviewed quoted in the Wall Street Journal, New York Times, and National Public Radio, Fortune, KNX 1070 Radio, Kaiser Health News, NBC Television News, The Capitol Forum and other media outlets. See and for more about the company.

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