Summary & Overview
CPT 86042: Acetylcholine Receptor Blocking Antibody Assay
CPT code 86042 denotes a laboratory immunology assay that detects acetylcholine receptor (AChR) blocking antibodies, a marker commonly used in the evaluation of myasthenia gravis (MG). This test is clinically important because detection of AChR blocking antibodies can support diagnosis and guide management for patients with suspected autoimmune neuromuscular junction disorders. Nationally, AChR antibody testing is performed across hospital and commercial laboratories and is a component of diagnostic pathways for neuromuscular weakness.
Key payers covered in this analysis include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. Readers will find an overview of the service context, typical sites of service, and clinical relevance of the assay. The publication also summarizes common billing considerations and modifiers used with laboratory tests, payer coverage patterns, and benchmarking information where available. Clinical context includes the role of AChR blocking antibodies in diagnosing myasthenia gravis and how laboratory results inform care pathways. Policy and reimbursement updates that affect access and coding practice are highlighted when present. Data not available in the input is noted where specific payer policies, associated taxonomies, ICD-10 pairings, or related codes are required but not provided.
Billing Code Overview
CPT code 86042 evaluates a specimen, such as serum, for acetylcholine receptor (AChR) blocking antibody using methods such as radioimmunoassay. The test measures noninfectious autoantibodies associated with myasthenia gravis (MG), an autoimmune disorder that disrupts the nerve‑to‑muscle interface and causes muscle weakness.
Service type: Clinical laboratory immunology test — antibody assay
Typical site of service: Clinical laboratory, hospital laboratory, or outpatient diagnostic testing center
Clinical & Coding Specifications
Clinical Context
A 45-year-old patient presents to a neurology clinic with fluctuating skeletal muscle weakness, ptosis, and intermittent diplopia. The neurologist performs a focused neuromuscular exam and orders serologic testing to evaluate for myasthenia gravis. A blood specimen (serum) is collected in the outpatient phlebotomy area and sent to the clinical laboratory for quantification of acetylcholine receptor (AChR) blocking antibodies by radioimmunoassay. The laboratory receives and accessioned the specimen, performs the radioimmunoassay, documents results in the laboratory information system, and releases a report to the ordering neurologist. The result aids the clinician in confirming autoimmune-mediated neuromuscular junction dysfunction and guiding further diagnostic workup such as neurophysiology testing or referral to a neuromuscular specialist. Typical site of service is outpatient clinic/phlebotomy or hospital outpatient laboratory; the service type is clinical laboratory serologic testing.
Coding Specifications
| Modifier | Description | When to Use |
|---|---|---|
00 | Default — no modifier | Use when no other modifier applies and full global service is provided |
26 | Professional component | Use when only the professional interpretation/reading of the laboratory result is billed separately |
52 | Reduced services | Use when the test was performed but substantially reduced in scope or time |
53 | Discontinued procedure | Use if specimen collection or testing was begun but stopped for reasons unrelated to patient condition |
59 | Distinct procedural service | Use when this test is billed separately from other services on the same day and is distinct and independent |
90 | Reference (outside) laboratory | Use when the specimen was forwarded to an external reference laboratory for testing |
91 | Repeat clinical diagnostic laboratory test | Use when the same test is repeated on the same day for monitoring or verification |
QW | CLIA waived test performed by a CLIA-certified person | Use when an applicable waived laboratory test is performed; not typically used for 86042 but included for labs' modifier sets |
TC | Technical component | Use when billing only the technical component of the laboratory test (equipment, reagents, technician time) |
90 | (Duplicate entry avoided) | (See above) |
| Taxonomy Code | Specialty | Notes |
|---|---|---|
2084P0800X | Neurology | Ordering clinicians evaluating suspected myasthenia gravis |
208000000X | Pathology & Laboratory Medicine | Providers overseeing laboratory testing and interpretation |
207L00000X | Allergy & Immunology | Specialists who may order antibody testing for autoimmune neuromuscular disorders |
2086S0500X | Physical Medicine & Rehabilitation | Clinicians involved in functional assessment and management of neuromuscular weakness |
362A0000X | Clinical Neurophysiology | Providers coordinating electrodiagnostic testing alongside serologic diagnosis |
Related Diagnoses
| ICD-10 Code | Description | Clinical Relevance |
|---|---|---|
G70.00 | Myasthenia gravis without (acute) exacerbation | Primary diagnosis for which AChR blocking antibody testing is ordered to support diagnosis |
G70.01 | Myasthenia gravis with (acute) exacerbation | Used when patient has worsening symptoms; antibody levels may assist in acute management decisions |
G70.81 | Lambert-Eaton myasthenic syndrome | Differential diagnosis for neuromuscular junction disorders; antibody testing helps distinguish etiologies |
R25.1 | Tremor, unspecified | Sometimes part of neuromuscular symptom evaluation though not specific; used when initial presentation is nonspecific |
H53.8 | Other visual disturbances | Used when ptosis or diplopia prompts evaluation for neuromuscular junction disorders |
M79.1 | Myalgia | Non-specific muscle weakness or pain coded during initial evaluation prior to definitive diagnosis |
R47.01 | Aphasia | Included when bulbar symptoms prompt evaluation for neuromuscular disease affecting speech and swallowing |
Related CPT Codes
| CPT Code | Description | Relationship to This Procedure |
|---|---|---|
86038 | Antinuclear antibody (ANA) with titer and reflex to pattern interpretation | May be ordered concurrently to evaluate for other autoimmune disorders that can cause neuromuscular symptoms |
86255 | Antibody, neurone-specific (e.g., anti-AChR binding) — note: 86255 often used for AChR binding antibody assays | Some labs perform AChR binding antibody assays billed under related immunology antibody CPTs when evaluating myasthenia gravis; complements blocking antibody testing |
95886 | Needle electromyography, 1 extremity with related paraspinal areas | Performed after serologic testing to assess neuromuscular junction and muscle electrical activity when diagnosing myasthenia gravis |
95930 | Repetitive nerve stimulation, up to 4 muscles | Electrodiagnostic study commonly used alongside AChR antibody testing to confirm disorder at the neuromuscular junction |
36415 | Collection of venous blood by venipuncture | Standard specimen collection charge associated with obtaining serum for 86042 testing |
88360 | Immunohistochemistry staining, per antibody — single stain | Occasionally used if tissue-based immunostaining is performed during broader autoimmune evaluations; less common but potentially related in complex workups |