Summary & Overview

CPT 86606: Aspergillus Antibody Immunoassay

CPT code 86606 denotes an immunoassay performed on a patient’s blood to detect antibodies to the fungus Aspergillus. This laboratory diagnostic code supports clinical care for suspected or ongoing fungal infections, including forms of aspergillosis, allergic bronchopulmonary aspergillosis, and monitoring immune response. Nationally, accurate use of 86606 affects laboratory reporting, clinical workflows, and payer coverage decisions for fungal serology testing.

Key payers covered in this analysis include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. The publication outlines how these major payers typically approach coverage and coding considerations for fungal antibody testing, and where common billing pitfalls occur.

Readers will find a concise clinical context for when an Aspergillus antibody immunoassay is ordered, typical sites of service, and operational implications for laboratories and clinicians. The piece also provides benchmark-oriented content on coding practice, common modifiers and billing adjustments (listed separately), and notes on documentation that supports medical necessity. Data not available in the input is clearly identified where applicable.

AetnaBlue Cross Blue ShieldCigna HealthUnitedHealthcareMedicare86606CPTimmunoassayAspergillusfungal serologyclinical laboratorydiagnostic testinglaboratory codingaspergillosis

Billing Code Overview

CPT code 86606 describes an immunoassay for detection of antibodies to the fungus Aspergillus. The test is performed by a laboratory analyst who evaluates a patient’s blood sample to determine the presence of Aspergillus-specific antibodies, commonly used in diagnosing or monitoring fungal infections such as aspergillosis.

Service type: Laboratory diagnostic immunoassay

Typical site of service: Clinical laboratory or hospital laboratory

Clinical & Coding Specifications

Clinical Context

A typical scenario involves an adult patient with chronic respiratory symptoms (cough, wheeze, hemoptysis, or recurrent pneumonia) or an immunocompromised patient with fever and pulmonary infiltrates on imaging. The clinician suspects allergic bronchopulmonary aspergillosis (ABPA), chronic pulmonary aspergillosis, or invasive aspergillosis and orders serologic testing. Blood is drawn at an outpatient phlebotomy station or hospital laboratory; the specimen is processed in the clinical laboratory where a technologist performs an immunoassay to detect Aspergillus-specific antibodies. Results guide diagnosis alongside imaging, sputum culture, and clinical presentation and may prompt antifungal therapy or further invasive testing such as bronchoscopy with lavage.

Coding Specifications

Modifier	Description	When to Use
`26`	Professional component	Use when reporting only the professional (interpretive) portion if the laboratory service has separate professional billing.
`TC`	Technical component	Use when reporting only the technical component (lab processing/equipment) of the test.
`90`	Reference (outside) laboratory	Use when the specimen is sent to an outside independent lab for testing.
`91`	Repeat clinical diagnostic lab test	Use when the test is repeated on the same day to obtain a subsequent result.
`52`	Reduced services	Use when the test is partially reduced or not fully performed.
`59`	Distinct procedural service	Use when multiple unrelated procedures are billed the same day and this test is distinct from others.
`62`	Two surgeons (team) — lab equivalent use rare	Use only in specific institutional billing scenarios when two qualified individuals share responsibility for a complex testing process.
`78`	Unplanned return to the lab procedure — rarely used	Use if an unplanned repeat of the laboratory procedure is required for the same patient during the postoperative or postprocedure period in institutional settings.
`80`	Assistant surgeon — lab equivalent use rare	Use only where applicable for supervisory/assistant billing relationships in complex institutional lab services.
`91`	Repeat clinical diagnostic lab test	(Duplicate entry removed in final use — see first `91` row)
`90`	Reference (outside) laboratory	(Duplicate entry removed in final use — see first `90` row)

Taxonomy Code	Specialty	Notes
207L00000X	Infectious Disease	Physicians ordering and interpreting serologic testing for fungal infections.
207K00000X	Pulmonary Disease	Pulmonologists evaluating suspected aspergillosis in chronic or allergic lung disease.
207P00000X	Pathology	Pathologists and laboratory directors overseeing immunoassay testing and quality control.
363L00000X	Clinical Laboratory	Clinical laboratory professionals and medical technologists performing the immunoassay.

Related Diagnoses

ICD-10 Code	Description	Clinical Relevance
`B44.0`	Invasive pulmonary aspergillosis	Direct indication for Aspergillus serology as part of diagnostic evaluation in immunocompromised patients.
`B44.7`	Disseminated aspergillosis	Systemic disease where serologic testing can support suspicion of invasive fungal infection.
`J69.0`	Aspiration pneumonitis due to food and vomit	Listed as a differential for pulmonary infiltrates; clinicians may test for fungal causes when clinical course is atypical.
`J84.10`	Pulmonary fibrosis, unspecified	Chronic lung disease patients may be at risk for colonization or allergic responses to Aspergillus; antibody testing can aid evaluation.
`J82`	Pulmonary eosinophilia	Conditions like ABPA present with eosinophilia; Aspergillus antibody testing is relevant to support ABPA diagnosis.

Related CPT Codes

CPT Code	Description	Relationship to This Procedure
`86607`	Antibody; Aspergillus, quantitative or semiquantitative	A closely related serologic assay that may be ordered for more detailed antibody titers when `86606` (qualitative) is insufficient for clinical interpretation.
`86664`	Antibody; Blastomyces dermatitidis	Other fungal serologies that may be ordered in the differential diagnosis of fungal pulmonary infections.
`87481`	Infectious agent antigen detection by immunoassay; Aspergillus, direct antigen detection	An antigen test that may be performed on serum or bronchoalveolar lavage as a complementary diagnostic test to antibody testing.
`87077`	Culture, bacterial; blood, aerobic, each isolate	Microbiologic cultures of blood or respiratory specimens often accompany serology to identify organisms or co-infection.
`88112`	Cytopathology, fluids, smears (e.g., bronchoalveolar lavage)	Cytology of respiratory specimens obtained by bronchoscopy which may be performed when serology suggests invasive disease.