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    v1.0.28
    OpenPayerBilling CodesTherapeutic Drug AssaysCPT cpt-80188-primidone-quantitative-assay
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    CPT 80188: Primidone Quantitation, Therapeutic Drug Monitoring

    CPT code 80188 describes a laboratory quantitative assay for primidone, an anticonvulsant medication; the service is a clinical laboratory test performed by a lab analyst to measure primidone concentration in a patient specimen, typically provided as a technical laboratory service in a hospital or independent clinical 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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    Table of contents

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    Clinical & Coding Specifications

    Clinical Context

    A typical patient is an adult or pediatric patient receiving antiepileptic therapy with primidone for seizure disorder or essential tremor who requires therapeutic drug monitoring. The clinician (neurologist, primary care physician, or movement disorders specialist) orders a serum primidone level when there is concern for subtherapeutic dosing, suspected toxicity, altered mental status, breakthrough seizures, signs of drug adverse effects (sedation, ataxia), potential drug interactions, or to establish baseline steady-state concentration after a dose change. Specimen collection is performed in an outpatient phlebotomy clinic, hospital inpatient unit, emergency department, or ambulatory infusion center. The specimen (serum or plasma) is sent to a clinical laboratory where a laboratory analyst performs the technical assay to quantitate primidone using methods such as high-performance liquid chromatography (HPLC) or mass spectrometry. The laboratory provides a numeric concentration with reference range and a technical report; a pathologist or clinical chemist may provide an interpretive comment if required. Results are routed to the ordering provider’s electronic health record and used to guide medication dose adjustments, additional testing, or clinical management.

    Related CPT Codes

    CPT CodeDescriptionRelationship to This Procedure
    80188Primidone; quantitation, each drug (technical component performed by lab analyst)This is the primary assay code for quantitating primidone concentration in serum or plasma.
    80150Antiepileptic drug assay; phenobarbital, per assayOften ordered alongside primidone levels because phenobarbital is pharmacologically related and may co-occur; used for comparative therapeutic monitoring.
    80307Drug confirmation by GC/MS, single or multiple drugs/metabolites; confirmation assayUsed when confirmatory testing by mass spectrometry is required for discrepant or critical toxicology results.
    36415Collection of venous blood by venipuncturePerformed prior to the laboratory analysis to obtain the specimen for 80188.

    Related Modifiers

    6 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…

    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…
    2084P0800XPsychiatry PhysicianA Psychiatrist specializes in the prevention, diagnosis, and treatment of mental disorders, emotional disorders, psychotic disorders, mood disorders, …
    207X00000XOrthopaedic Surgery PhysicianAn orthopaedic surgeon is trained in the preservation, investigation and restoration of the form and function of the extremities, spine and associated…
    213E00000XPodiatristA podiatrist is a person qualified by a Doctor of Podiatric Medicine (D.P.M.) degree, licensed by the state, and practicing within the scope of that l…
    251300000XLocal Education Agency (LEA)The term local education agency means a public board of education or other public authority legally constituted within a State to either provide admin…
    3336C0004XCompounding PharmacyA pharmacy that specializes in the preparation of components into a drug preparation as the result of a Practitioner's Prescription Drug Order or init…
    261QM0855XAdolescent and Children Mental Health Clinic/CenterAn entity, facility, or distinct part of a facility providing diagnostic, treatment, and prescriptive services related to mental and behavioral disord…

    Related ICD-10-CM Codes

    25 rows

    ICD-10-CM CodeDescription
    E66.9Obesity, unspecified
    F06.8Other specified mental disorders due to known physiological condition
    F07.0Personality change due to known physiological condition
    F12.20Cannabis dependence, uncomplicated
    F33.1Major depressive disorder, recurrent, moderate
    F44.5Conversion disorder with seizures or convulsions
    G21.9Secondary parkinsonism, unspecified
    G25.0Essential tremor
    G40.101Localization-related (focal) (partial) symptomatic epilepsy and epileptic syndromes with simple partial seizures, not intractable, with status epilepticus
    G40.111Localization-related (focal) (partial) symptomatic epilepsy and epileptic syndromes with simple partial seizures, intractable, with status epilepticus

    Showing 1–10 of 25

    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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