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    v1.0.28
    OpenPayerBilling CodesTherapeutic Drug AssaysCPT cpt-80340-multiple-antiepileptic-drug-assay-4-to-6-agents
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    CPT 80340: Antiepileptic (Anticonvulsant) Panel, 4–6 Drugs

    CPT code 80340 reports laboratory testing that measures or detects the presence of four to six antiepileptic (anticonvulsant/antiseizure) medications in a patient specimen; this is a clinical toxicology/therapeutic drug monitoring service typically performed by a clinical laboratory using validated assay methods and is commonly ordered for outpatient or inpatient care when medication levels or polytherapy monitoring are required.

    For related coverage guidance, see recent payer policy updates: Epithelial Cell Cytology in Breast Cancer Risk Assessment, Chemotherapy Observation or Inpatient Hospitalization (for New Mexico Only), Antibody-Drug Conjugates.

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    Clinical & Coding Specifications

    Clinical Context

    A 28-year-old patient with known focal epilepsy on multiple antiseizure medications presents for routine therapeutic drug monitoring after a seizure recurrence. The clinician orders comprehensive antiepileptic drug level testing because the patient is taking several anticonvulsants and the exact agents or combinations are not covered by single-drug assays. A blood specimen is collected in the ambulatory lab or hospital phlebotomy unit and sent to the clinical chemistry/toxicology laboratory. The lab analyst performs a quantitative or qualitative assay that measures or detects the presence of four to six antiepileptic agents in the specimen, generating results used by the neurologist or primary care provider to adjust dosing, assess adherence, or investigate toxicity. Typical site of service includes hospital outpatient laboratory, independent clinical laboratory, or inpatient hospital laboratory; ordering providers commonly include neurologists, psychiatrists, or emergency medicine clinicians.

    Related CPT Codes

    CPT CodeDescriptionRelationship to This Procedure
    80104Drug screen, qualitative; multiple drug classes by presumptive test, capable of being read by direct optical observationOften performed as an initial rapid screen for multiple agents prior to specific antiepileptic quantification.
    80331Drug analysis, qualitative; illicit drugs, simultaneous assay of multiple drugs, instrumented methodMay be used in parallel when concern for nonprescribed substances or polypharmacy exists.
    80341Antiepileptic drug assay, complex, quantitative, four to six drugs (specific analytes specified in code)Closely related; used when the panel targets specific named antiepileptics covered by other CPT coding — 80340 is for unspecified antiepileptics.
    84133Assay of drug, multiple anticonvulsants, quantitative, eachIndividual anticonvulsant quantitative assays may be ordered alongside a panel for specific therapeutic ranges.
    36415Collection of venous blood by venipunctureCommonly performed prior to running 80340 to obtain the patient specimen.
    82542Therapeutic drug assay, other; multiple drugs (example code for drug monitoring panels)Represents additional therapeutic drug monitoring panels that may be billed in conjunction with antiepileptic testing.

    Related Modifiers

    7 rows

    ModifierDescriptionWhen to Use
    22Modifier –22 (Increased Procedural Services) is used when a reported procedure is substantially more extensive than normally required. The CPT Manual and CMS state it may be appended only when the…- When to use: Append modifier -22 to a procedural CPT code when the service performed is substantially more extensive than the usual service described by that code — i.e., the procedure required…
    26Modifier 26 (Professional Component) identifies and bills only the professional portion of a split service — the physician’s interpretation, report, and medical judgment — when the technical…- Use CPT Modifier -26 when you are billing only the professional component (PC) of a split‑bill eligible service—i.e., you performed the physician interpretation, medical judgment and prepared a…
    52Modifier ‑52 (Reduced Services) indicates that a service or procedure was partially reduced or omitted at the provider’s discretion, allowing reporting of the basic procedure number with a qualifier…- Use modifier -52 when a physician or qualified health professional electively reduces or omits part of a procedure or service (for example, performing fewer required views or omitting a portion of…
    53Modifier 53 (Discontinued Procedure) signals that a surgical or diagnostic service was begun by the physician but terminated because of extenuating circumstances that threatened the patient’s…- Use modifier -53 when a physician/qualified healthcare professional has started a surgical or diagnostic procedure (e.g., anesthesia administered, incision or scope insertion) and then discontinues…
    62Modifier 62 indicates that two surgeons function as co‑surgeons, each performing distinct parts of the same primary surgical procedure. It is appended to the primary procedure code (and any…- Use modifier -62 when two surgeons act as co‑surgeons (both primary surgeons) on a single definitive primary procedure, each performing distinct parts of the same surgical procedure (append -62 to…
    78CPT modifier -78 indicates an unplanned, related return to the operating or procedure room by the same provider during the global postoperative period. It is appended when treatment for a…- Use modifier -78 when an unplanned, related complication during the original procedure’s global postoperative period requires the patient to return to a formal operating or procedure room and the…
    90Modifier ‑90 (Reference/Outside Laboratory) indicates that a laboratory test was performed by an entity other than the treating or reporting provider. The American Medical Association defines…- Use CPT modifier -90 when a laboratory test is performed by an outside/reference laboratory (an entity other than the treating or reporting physician or qualified professional) and the claim needs…

    Related Provider Taxonomies

    8 rows

    Taxonomy CodeSpecialtyNotes
    207RH0000XHematology (Internal Medicine) PhysicianAn internist with additional training who specializes in diseases of the blood, spleen and lymph. This specialist treats conditions such as anemia, cl…
    2084P0800XPsychiatry PhysicianA Psychiatrist specializes in the prevention, diagnosis, and treatment of mental disorders, emotional disorders, psychotic disorders, mood disorders, …
    208000000XPediatrics PhysicianA pediatrician is concerned with the physical, emotional and social health of children from birth to young adulthood. Care encompasses a broad spectru…
    2084N0400XNeurology PhysicianA Neurologist specializes in the diagnosis and treatment of diseases or impaired function of the brain, spinal cord, peripheral nerves, muscles, auton…
    252Y00000XEarly Intervention Provider AgencyEarly intervention services are an effective way to address the needs of infants and toddlers who have developmental delays or disabilities. The servi…
    2080B0002XPediatric Obesity Medicine PhysicianA physician who specializes in the treatment of obesity demonstrates competency in and a thorough understanding of the treatment of obesity and the ge…
    207RT0003XTransplant Hepatology PhysicianAn internist with special knowledge and the skill required of a gastroenterologist to care for patients prior to and following hepatic transplantation…
    2088P0231XPediatric Urology PhysicianSurgeons who can diagnose, treat, and manage children's urinary and genital problems. A pediatric urologist devotes a minimum of 50% of his or her pra…

    Related Payer Policy Updates

    Specialty: Hematology/Oncology1 / 2

    4 rows

    PolicyPayerEffective Date
    Epithelial Cell Cytology in Breast Cancer Risk AssessmentOscar Health2026-10-01
    Chemotherapy Observation or Inpatient Hospitalization (for New Mexico Only)UnitedHealthcare2026-08-01
    Antibody-Drug ConjugatesPremera Bluecross2026-08-01
    Umbilical Cord Blood Harvesting and Storage for Future Use (for Indiana Only)UnitedHealthcare2026-08-01

    Related Codes

    CPT-80143-ACETAMINOPHEN-QUANTITATIVE-SERUM-ASSAY

    CPT 80143: Acetaminophen Quantitative Assay

    CPT-80145-ADALIMUMAB-LEVEL-ASSAY-THERAPEUTIC-DRUG-MONITORING

    CPT 80145: Adalimumab Quantitative Drug Level Assay

    CPT-80150-AMIKACIN-QUANTITATIVE-ASSAY-THERAPEUTIC-DRUG-MONITORING

    CPT 80150: Amikacin Quantitative Serum Level

    CPT-80151-AMIODARONE-QUANTITATIVE-SERUM-ASSAY

    CPT 80151: Amiodarone Quantitative Drug Level Assay

    CPT-80155-CAFFEINE-LEVEL-TESTING

    CPT 80155: Caffeine Level Quantification

    CPT-80156-CARBAMAZEPINE-TOTAL-LEVEL-LAB-ASSAY

    CPT 80156: Carbamazepine Total Level (Serum)

    CPT-80157-FREE-CARBAMAZEPINE-ASSAY

    CPT 80157: Free Carbamazepine Quantitative Assay

    CPT-80158-CYCLOSPORINE-QUANTITATIVE-ASSAY-LAB

    CPT 80158: Cyclosporine Quantitation, Laboratory

    CPT-80159-CLOZAPINE-LEVEL-ASSAY-THERAPEUTIC-DRUG-MONITORING

    CPT 80159: Clozapine Level Measurement

    CPT-80161-CARBAMAZEPINE-EPOXIDE-QUANTITATIVE-ASSAY

    CPT 80161: Carbamazepine 10,11-Epoxide Level, Quantitative

    Showing 1–10 of 87

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    Frequently Asked Questions

    References

    1. 1.CPT® Codes and Descriptions. AAPC. Retrieved Aug 11, 2026.Maintains the CPT code set's official descriptions and guidelines, licensed from the American Medical Association, used as the definitional source for CPT codes on this page.
    2. 2.HCPCS Quarterly Update. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's quarterly release of HCPCS Level II codes and short/long descriptors, the source for HCPCS code definitions and update history.
    3. 3.ICD-10-CM Full Code List. Centers for Medicare & Medicaid Services (CMS). Retrieved Aug 11, 2026.CMS's complete ICD-10-CM diagnosis code list, used to cross-reference diagnosis codes associated with this procedure or service.
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