CPT 0043U: TBRF Borrelia ImmunoBlot IgM Test

CPT code 0043U identifies a proprietary immunoblot serology test marketed by IGeneX Inc. that detects IgM antibodies to four recombinant Borrelia protein groups associated with Tick–Borne Relapsing Fever (TBRF). As a PLA code, 0043U is specific to a single manufacturer's assay and signals unique clinical and contracting considerations for payers, providers, and laboratories. Nationally, specialized serologic assays for tick-borne infections are significant due to growing clinician demand for targeted diagnostics in complex cases of suspected Lyme disease and relapsing fever.

Key payers in this analysis include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a concise account of what 0043U represents, typical settings where the test is performed, and the scope of coverage considerations tied to proprietary laboratory assays. The publication summarizes benchmark topics relevant to this code, including coding classification as a PLA, implications for laboratory billing and test ordering workflows, and the clinical context for IgM-based Borrelia testing. Where input data is missing, the report notes those gaps as "Data not available in the input."

Billing Code Overview

CPT code 0043U is a Proprietary Laboratory Analyses (PLA) code for the Tick–Borne Relapsing Fever (TBRF) Borrelia ImmunoBlot IgM test developed by IGeneX Inc. The test detects IgM antibodies to four recombinant protein groups of Borrelia, the tick-borne bacteria associated with Lyme disease and relapsing fever.

Service Type: Laboratory diagnostic testing (proprietary immunoblot serology)

Typical Site of Service: Clinical laboratory or specialized reference laboratory

Data not available in the input.

Clinical Context

A 34-year-old patient presents to an infectious disease clinic with several weeks of intermittent fevers, recurrent headaches, fatigue, and a history of recent tick exposure while hiking in an endemic area. The clinician suspects tick-borne relapsing fever (TBRF) or another Borrelia-related infection and orders a specialized serologic test to detect early immune response. The specimen (serum) is collected in the outpatient laboratory or clinic phlebotomy area and sent to IGeneX Inc. for the proprietary Tick–Borne Relapsing Fever Borrelia ImmunoBlot IgM assay (0043U). Results are reviewed by the ordering clinician; a positive IgM immunoblot supports recent or acute infection and informs further management, public health reporting if applicable, and possible confirmatory testing or treatment decisions. Typical sites of service include outpatient clinic, outpatient laboratory, urgent care, and reference laboratory processing.

Coding Specifications

Modifier	Description	When to Use
`00`	Default — no modifier	Use when no special circumstances apply to the billed service.
`11`	Professional component

Taxonomy Code	Specialty	Notes
207RH0000X	Infectious Disease	Infectious disease physicians frequently order and interpret specialized Borrelia serologies.
208D00000X	Clinical Pathology	Clinical pathologists oversee laboratory testing, quality, and result interpretation workflows.
207K00000X	Family Medicine	Primary care and family medicine clinicians commonly order initial tick-borne disease testing.
207L00000X	Internal Medicine	General internists evaluate and order diagnostic testing for suspected systemic infections.
2080P0006X	Medical Laboratory Scientist	Laboratory professionals perform specimen processing and technical components of testing.

Related Diagnoses

ICD-10 Code	Description	Clinical Relevance
`A69.2`	Lyme disease	Borrelia species cause Lyme disease; serologic testing for Borrelia antibodies is directly relevant when differential includes Lyme disease.
`A69.23`	Post-Lyme disease syndrome	Patients with persistent symptoms after tick exposure may be evaluated with specialized Borrelia serologies.
`A77.0`	Spotted fever due to Rickettsia rickettsii	Other tick-borne infections considered in differential when ordering comprehensive tick-borne panels.
`A83.9`	Viral encephalitis, unspecified	Neurologic manifestations in differential diagnosis may prompt evaluation for neuroborreliosis with specialized serology.
`R50.9`	Fever, unspecified	Common presenting symptom that leads to ordering of infectious disease serologies including Borrelia ImmunoBlot IgM.
`R53.1`	Weakness	Non-specific systemic symptom leading clinicians to evaluate for infectious etiologies after tick exposure.
`M79.1`	Myalgia	Musculoskeletal pain common in Borrelia infections; supports need for targeted serologic testing.
`G01`	Meningitis in bacterial diseases classified elsewhere	When central nervous system involvement is suspected from tick-borne bacteria, laboratory serology contributes to diagnosis.

Related CPT Codes

CPT Code	Description	Relationship to This Procedure
`80048`	Basic metabolic panel (BMP)	Often ordered alongside infectious disease testing to assess baseline metabolic status and organ function prior to treatment.
`86580`	Skin test for tuberculosis (tine test)	May be ordered in the differential evaluation for febrile illnesses or when evaluating immune status; not specific but commonly used in infectious workups.
`87471`	Infectious agent detection by nucleic acid (for example, Borrelia)	Molecular testing for Borrelia species may be ordered in parallel or as confirmatory testing to serology depending on clinical suspicion and timing of illness.
`87070`	Culture, bacterial; any source except blood, aerobic	When suspicious for concurrent bacterial infections or to evaluate secondary infections from tick exposures, cultures may be obtained.
`99000`	Handling and/or conveyance of a specimen for transfer from the patient to the laboratory	Billed when specimen handling or transfer services apply in the specimen transport chain to a reference lab.

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Summary & Overview