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    v1.0.30
    OpenPayerBilling CodesTherapeutic Drug AssaysCPT cpt-80156-carbamazepine-total-level-lab-assay
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    CPT 80156: Carbamazepine Total Level (Serum)

    CPT code 80156 describes a laboratory therapeutic drug monitoring test for the total serum concentration of carbamazepine (bound plus unbound) performed by a lab analyst; the service is a clinical chemistry/therapeutic drug assay typically provided in an outpatient laboratory or hospital clinical laboratory setting on a patient specimen to inform medication management for epilepsy and related neurologic or psychiatric conditions.

    For related coverage guidance, see recent payer policy updates: Long-Acting Injectable Antiretroviral Agents for HIV, B-Hemolytic Streptococcus Testing, Human Immunodeficiency Virus (HIV) — Coverage Criteria for Testing and Resistance Assays.

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    Clinical & Coding Specifications

    Clinical Context

    A 28-year-old patient with focal epilepsy treated with carbamazepine presents for routine therapeutic drug monitoring after a recent dose adjustment due to seizure recurrence. The clinician orders a laboratory assay to measure the total carbamazepine concentration (bound plus unbound) to confirm therapeutic range and assess adherence, drug interactions, or toxicity risk. A phlebotomy technician collects a serum specimen at a scheduled outpatient laboratory draw or hospital inpatient lab, following facility specimen-handling protocol. The specimen is labeled and transported to the clinical laboratory where a lab analyst performs the technical assay corresponding to 80156. Results are reported to the ordering provider and incorporated into medication management decisions; reflex testing or repeat levels may be ordered if results are inconsistent with clinical status or timing of last dose.

    Related CPT Codes

    CPT CodeDescriptionRelationship to This Procedure
    36415Collection of venous blood by venipunctureSpecimen collection required before performing the 80156 assay
    82570Drug assay, qualitative; multiple drug classes — Not typically used for carbamazepine levelsNot applicable — included only if screening panels are performed prior to specific quantification
    80307Drug test(s), definitive; multiple drug classes, includes confirmationMay be used when confirmation testing using mass spectrometry is performed for therapeutic or forensic purposes
    80156Carbamazepine; total level (bound + unbound)The primary technical assay code describing the laboratory analysis performed
    80053Comprehensive metabolic panelOften ordered concurrently to assess organ function that affects drug metabolism and toxicity risk

    Related Modifiers

    9 rows

    ModifierDescriptionWhen to Use
    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…
    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…
    91Modifier 91 — “Repeat Clinical Diagnostic Laboratory Test” — is appended when the exact same CPT laboratory test is performed more than once for the same patient on the same day because serial,…- Use modifier 91 when the exact same CPT laboratory test is performed more than once on the same patient on the same date because serial or repeated testing is medically necessary to monitor…
    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…
    59Modifier 59 indicates a distinct procedural service when two procedures that are not normally billed together are clinically and procedurally separate. The CPT definition (as reiterated by CMS)…- Use modifier -59 to report a distinct procedural service when documentation supports that the procedure reported is not normally billed together with another service on the same day because of a…
    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…
    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…
    80CPT® Modifier 80 (Assistant Surgeon) is appended to a surgical CPT code when a physician (MD or DO) provides full, continuous assistance throughout the operative procedure. It is intended only for…- Use CPT Modifier -80 when a physician (MD or DO) serves as an assistant surgeon and provides full, continuous assistance throughout the entire operative procedure; append -80 to the surgical CPT…

    Related Provider Taxonomies

    8 rows

    Taxonomy Code
    183500000X
    207L00000X
    208000000X
    207Q00000X
    261QM1103X
    246QI0000X
    247ZC0005X
    335U00000X

    Related ICD-10-CM Codes

    28 rows

    ICD-10-CM CodeDescription
    E11.9Type 2 diabetes mellitus without complications
    F06.31Mood disorder due to known physiological condition with depressive features
    F07.9Unspecified personality and behavioral disorder due to known physiological condition
    F31.73Bipolar disorder, in partial remission, most recent episode manic
    F31.9Bipolar disorder, unspecified
    F32.9Major depressive disorder, single episode, unspecified
    F33.1Major depressive disorder, recurrent, moderate
    G24.3Spasmodic torticollis
    G25.0Essential tremor
    G40.111Localization-related (focal) (partial) symptomatic epilepsy and epileptic syndromes with simple partial seizures, intractable, with status epilepticus

    Showing 1–10 of 28

    Related Payer Policy Updates

    Specialty: Infectious Disease1 / 3

    10 rows

    PolicyPayerEffective Date
    Long-Acting Injectable Antiretroviral Agents for HIVColorado Rocky Mountain Health Plans2026-10-01
    B-Hemolytic Streptococcus TestingOscar Health2026-10-01
    Human Immunodeficiency Virus (HIV) — Coverage Criteria for Testing and Resistance AssaysOscar Health2026-10-01
    Hepatitis Testing (A, B, C, D) Coverage CriteriaOscar Health2026-10-01
    Lyme Disease Testing Coverage CriteriaOscar Health2026-10-01
    Pathogen Panel TestingOscar Health2026-10-01
    Diagnostic Testing of Common Sexually Transmitted InfectionsOscar Health2026-10-01
    Coronavirus Testing in the Outpatient SettingOscar Health2026-10-01
    Testing for Vector-Borne InfectionsOscar Health2026-10-01
    Testing for Diagnosis of Active or Latent TuberculosisOscar Health2026-10-01

    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-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

    CPT-80162-DIGOXIN-TOTAL-THERAPEUTIC-DRUG-MONITORING

    CPT 80162: Total Digoxin Level in Serum

    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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