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    v1.0.28
    OpenPayerBilling CodesTherapeutic Drug AssaysCPT cpt-80193-teriflunamide-level-assay-therapeutic-drug-monitoring
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    CPT 80193: Teriflunomide (Leflunomide Metabolite) Quantitative Assay

    CPT code 80193 describes a laboratory test in which the lab analyst performs the technical procedure to quantify the active metabolite of leflunomide (teriflunomide) in a patient specimen; this is a therapeutic drug monitoring assay used for patients on the DMARD leflunomide and is typically provided as a clinical laboratory service in an outpatient laboratory or hospital laboratory setting.

    For related coverage guidance, see recent payer policy updates: B-Hemolytic Streptococcus Testing, Human Immunodeficiency Virus (HIV) — Coverage Criteria for Testing and Resistance Assays, Hepatitis Testing (A, B, C, D) Coverage Criteria.

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    Clinical & Coding Specifications

    Clinical Context

    A 56-year-old adult patient with established rheumatoid arthritis (RA) is receiving leflunomide as a disease‑modifying antirheumatic drug (DMARD). The treating rheumatologist orders a therapeutic drug monitoring assay to quantify the active metabolite teriflunomide to assess medication adherence, evaluate subtherapeutic or supratherapeutic exposure, or investigate suspected toxicity (for example, unexplained hepatotoxicity or persistent symptoms despite therapy). A blood specimen is collected at the ambulatory phlebotomy station or hospital laboratory, labeled, and transported to the clinical chemistry or specialty pharmacology laboratory. The laboratory analyst performs the technical wet‑lab testing and quantification of teriflunomide levels using validated methods (for example, liquid chromatography–tandem mass spectrometry). The laboratory issues a technical report with measured concentration and reference intervals to the ordering provider; the rheumatologist integrates the result into clinical management decisions, such as dose adjustment, drug holiday, or alternate DMARD selection. Typical site of service: outpatient hospital laboratory, independent reference laboratory, or hospital inpatient laboratory when monitoring therapy in admitted patients.

    Related CPT Codes

    CPT CodeDescriptionRelationship to This Procedure
    80194Therapeutic drug assay, qualitative or quantitative, for other immunosuppressive or antirheumatic agents (example)Alternative or companion drug level testing for other DMARDs or immunosuppressants when broader therapeutic monitoring is performed
    80307Drug assay, presumptive, any number of drug classes; qualitative, multiple classesMay be used in differential evaluation if substance use or polypharmacy is suspected but does not quantify teriflunomide
    84143Thyroid stimulating hormone (TSH)Common laboratory test ordered alongside DMARD monitoring to evaluate symptoms that could mimic therapy adverse effects
    84460Thyroxine; free (FT4)Often paired with TSH during systemic symptom evaluation in RA patients on DMARDs
    80061Lipid panelBaseline and monitoring labs commonly ordered in patients on chronic DMARD therapy to assess cardiovascular risk

    Related Modifiers

    7 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…
    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…
    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…
    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 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…
    207L00000XAnesthesiology PhysicianAn anesthesiologist is trained to provide pain relief and maintenance, or restoration, of a stable condition during and immediately following an opera…
    363A00000XPhysician AssistantA physician assistant is a person who has successfully completed an accredited education program for physician assistant, is licensed by the state and…
    207ZH0000XHematology (Pathology) PhysicianA hematopathologist is expert in diseases that affect blood cells, blood clotting mechanisms, bone marrow and lymph nodes. This physician has the know…
    163WW0000XWound Care Registered NurseNursing Service Providers · Registered Nurse
    247ZC0005XClinical Laboratory Director (Non-physician)An individual who is state-licensed as a clinical laboratory director and meets the qualifications in the Clinical Laboratory Improvement Amendments o…
    364SW0102XWomen's Health Clinical Nurse SpecialistPhysician Assistants & Advanced Practice Nursing Providers · Clinical Nurse Specialist
    261QM1101XMilitary and U.S. Coast Guard Ambulatory Procedure Clinic/CenterThat part of a "fixed" (non-temporary, non-deployed) DoD or Coast Guard entity furnishing surgical procedures requiring medically supervised recovery.…

    Related Payer Policy Updates

    Specialty: Infectious Disease1 / 3

    9 rows

    PolicyPayerEffective Date
    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
    Testing for Vector-Borne InfectionsOscar Health2026-10-01
    Coronavirus Testing in the Outpatient SettingOscar 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-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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