CPT 86051 Aquaporin-4 ELISA Reimbursement

CPT code 86051 represents an ELISA-based serologic test for antibodies to aquaporin-4, a clinically important biomarker for neuromyelitis optica (NMO). As an objective laboratory assay that helps distinguish NMO from multiple sclerosis and other inflammatory demyelinating disorders, this test has national relevance for neurology, immunology, and laboratory medicine practices. CPT code 86051 is used when laboratories perform an ELISA on a serum specimen to identify aquaporin-4 autoantibodies.

Key payers included in this overview are Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find a concise explanation of the clinical context and laboratory service represented by the code, typical sites of service, and the common modifiers associated with billing for laboratory procedures. The publication summarizes what to expect in coverage and billing workflows at a national level, highlights clinical implications for differential diagnosis of demyelinating diseases, and identifies where input data were not available.

This summary is intended to give clinicians, laboratorians, and billing professionals a clear, national-level portrait of CPT code 86051, including the clinical use case, service classification, and payers commonly relevant to reimbursement and claims processing.

Billing Code Overview

CPT code 86051 describes an enzyme-linked immunosorbent assay (ELISA) performed to detect antibodies to aquaporin-4 in a serum specimen. The presence of an aquaporin-4 antibody is a key diagnostic marker for neuromyelitis optica (NMO), an autoimmune disorder that primarily affects the optic nerves and spinal cord and can be misdiagnosed as multiple sclerosis.

Service Type: Laboratory test — serologic antibody assay (ELISA)

Typical Site of Service: Clinical laboratory or hospital laboratory; specimen collected in outpatient or inpatient settings

Clinical Context

A 38-year-old female presents to neurology with subacute bilateral optic neuritis and longitudinally extensive transverse myelitis. Prior treatment for presumed multiple sclerosis produced incomplete response. The neurologist orders testing for aquaporin-4 (AQP4) antibody to evaluate for neuromyelitis optica spectrum disorder (NMOSD). A serum specimen is collected in the outpatient phlebotomy lab during the clinic visit and sent to the hospital or reference laboratory. The laboratory performs an enzyme-linked immunosorbent assay (ELISA) to detect AQP4-IgG. Results are reported to the ordering neurologist and documented in the electronic health record; a positive result supports a diagnosis of NMOSD and informs immunotherapy selection.

Coding Specifications

Modifier	Description	When to Use
`26`	Professional component	When billing separate physician interpretation for the laboratory test (rare for automated ELISA labs).
`52`	Reduced services	When the laboratory test was partially performed or limited by specimen quantity/quality.

Taxonomy Code	Specialty	Notes
`2084P0800X`	Neurology	Ordering specialty for suspected NMOSD.
`207K00000X`	Clinical Laboratory	Laboratory performing the ELISA testing.
`207L00000X`	Pathology	May oversee laboratory testing and quality control.
`363L00000X`	Phlebotomy	Performs specimen collection in outpatient or hospital settings.

Related Diagnoses

ICD-10 Code	Description	Clinical Relevance
`G36.0`	Neuromyelitis optica [Devic]	Primary diagnosis associated with AQP4 antibody testing; a positive `86051` supports this diagnosis.
`H46.9`	Optic neuritis, unspecified	Optic neuritis is a common presenting feature prompting AQP4 antibody testing.
`G37.9`	Demyelinating disease of central nervous system, unspecified	Used when demyelinating process is suspected while distinguishing MS from NMOSD.
`G04.89`	Other encephalitis, myelitis and encephalomyelitis	Used for inflammatory spinal cord or brainstem presentations where AQP4 testing is considered.
`R25.9`	Unspecified abnormal involuntary movements	Symptom code occasionally used in broader neurologic workups that include AQP4 testing.

Related CPT Codes

CPT Code	Description	Relationship to This Procedure
`86051`	Antibody; aquaporin-4 (AQP4) (e.g., neuromyelitis optica)	Primary test to detect AQP4-IgG by ELISA; confirms NMOSD diagnosis in appropriate clinical context.
`36415`	Collection of venous blood by venipuncture	Specimen collection commonly performed prior to sending serum for `86051`.
`88342`	Immunohistochemistry or immunocytochemistry, per specimen; initial single antibody stain	May be used in specialized pathology workflows for antibody localization studies (rarely ordered alongside `86051`).
`80305`	Drug screen, presumptive, any number of drug classes; non-automated	Not directly related but commonly ordered in neurology admissions to rule out toxic causes when evaluating acute neurologic deficits.
`85025`	Complete blood count (CBC) with automated differential	Routine baseline studies often ordered during diagnostic workup for autoimmune neurologic disease.

OpenPayer

Summary & Overview

CPT 86051: Aquaporin-4 Antibody ELISA for Neuromyelitis Optica