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    OpenPayerBilling CodesHLA TypingCPT cpt-81373-hla-class-i-low-intermediate-resolution
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    CPT 81373: HLA Typing, Low or Intermediate Resolution, One Class I Locus

    CPT code 81373 describes the technical laboratory procedure for low- or intermediate-resolution molecular testing of human leukocyte antigen (HLA) genes for a single Class I locus; this service is a molecular HLA typing test performed by a lab analyst using molecular techniques and is typically provided as a laboratory/diagnostic service in a clinical laboratory or hospital lab setting.

    For related coverage guidance, see recent payer policy updates: Oral Cancer Screening and Testing, RTM Testing for Alpha-1 Antitrypsin Deficiency, Cytochrome P450 Genotype-Guided Treatment Strategy Corporate Medical Policy.

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    Table of contents

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    Clinical & Coding Specifications

    Clinical Context

    A 32-year-old patient being evaluated for organ transplantation requires HLA typing to assess donor–recipient compatibility. A clinician orders low- or intermediate-resolution molecular testing for a single Class I HLA locus (HLA-A, HLA-B, or HLA-C). The specimen (peripheral blood or buccal swab) is collected in the outpatient infusion center or transplant clinic and sent to the molecular pathology laboratory. The laboratory analyst performs the technical component of the assay, including DNA extraction, amplification (e.g., PCR-based methods), and allele detection appropriate for low/intermediate resolution. Results are reviewed by the laboratory director or molecular pathologist and reported to the transplant team to inform donor selection and immunologic risk assessment. Typical site of service is an outpatient molecular diagnostics laboratory or hospital-based clinical laboratory supporting transplant services.

    Related CPT Codes

    CPT CodeDescriptionRelationship to This Procedure
    81373HLA typing; low or intermediate resolution, one class I locus (technical component)Primary procedure: technical laboratory testing for one Class I HLA locus using molecular techniques
    81374HLA typing; low or intermediate resolution, one class II locusCommonly ordered alongside Class I testing when extended HLA typing (Class II) is needed for transplantation
    81376HLA typing; high resolution, one class I or class II locusMay be ordered when higher resolution allele-level typing is required after initial low/intermediate results
    86850Tissue typing set including lymphocytotoxic testingHistorical or complementary serologic tissue typing that may be performed in transplant evaluation
    0022UHLA typing, sequencing-based methods (proprietary, example)Alternative molecular sequencing-based tests that may be performed in the molecular lab as part of comprehensive HLA analysis

    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…
    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…
    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…

    Related Provider Taxonomies

    8 rows

    Taxonomy Code
    207Q00000X
    207L00000X
    207RC0000X
    363A00000X
    207XX0005X
    163WW0101X
    146L00000X
    106S00000X

    Related ICD-10-CM Codes

    26 rows

    ICD-10-CM CodeDescription
    A41.9Sepsis, unspecified organism
    B20Human immunodeficiency virus [HIV] disease
    C91.00Acute lymphoblastic leukemia not having achieved remission
    C92.00Acute myeloblastic leukemia, not having achieved remission
    C95.90Leukemia, unspecified not having achieved remission
    D47.Z2Castleman disease
    D66Hereditary factor VIII deficiency
    D67Hereditary factor IX deficiency
    D68.9Coagulation defect, unspecified
    I10Essential (primary) hypertension

    Showing 1–10 of 26

    Related Payer Policy Updates

    Specialty: Genetic & Molecular Testing1 / 3

    10 rows

    PolicyPayerEffective Date
    Oral Cancer Screening and TestingOscar Health2027-01-01
    RTM Testing for Alpha-1 Antitrypsin DeficiencyOscar Health2027-01-01
    Cytochrome P450 Genotype-Guided Treatment Strategy Corporate Medical Policybcbsvermont2027-01-01
    Carrier Testing Panels for Genetic Diseases (for Kentucky Only)UnitedHealthcare2026-10-01
    Genetic Testing for Neurological Disorders (for Kansas Only)UnitedHealthcare2026-10-01
    Genetic and Molecular TestingProvidence Health Plan2026-10-01
    Cell-Free Fetal DNA Testing (for Idaho Only)UnitedHealthcare2026-10-01
    Next Generation Sequencing for Minimal Residual Disease DetectionProvidence Health Plan2026-10-01
    Pharmacogenetic Panel Testing (for Kansas Only)UnitedHealthcare2026-10-01
    Non-Covered Genetic Panel TestsProvidence Health Plan2026-10-01

    Related Codes

    CPT-81370-HLA-CLASS-I-II-LOW-INTERMEDIATE-RESOLUTION-TESTING

    CPT 81370: HLA Class I and II Low/Intermediate Resolution Typing

    CPT-81371-HLA-A-B-DRB1-LOW-INTERMEDIATE-RESOLUTION-TYPING

    CPT 81371: Low/Intermediate-Resolution HLA-A, -B, and -DRB1 Typing

    CPT-81372-HLA-CLASS-I-LOW-INTERMEDIATE-RESOLUTION-TYPING

    CPT 81372: HLA Class I Low/Intermediate Resolution Typing

    CPT-81374-HLA-CLASS-I-LOW-INTERMEDIATE-RESOLUTION

    CPT 81374: HLA Class I Allele Group Typing, Low/Intermediate Resolution

    CPT-81375-HLA-CLASS-II-LOW-INTERMEDIATE-RESOLUTION-TYPING

    CPT 81375: HLA Class II Low/Intermediate-Resolution Molecular Typing

    CPT-81376-HLA-CLASS-II-TYPING-LOW-INTERMEDIATE-RESOLUTION-TECHNICAL

    CPT 81376: HLA Class II Low/Intermediate Resolution, Technical Test

    CPT-81377-HLA-CLASS-II-ALLELE-GROUP-TYPING-LOW-INTERMEDIATE-RESOLUTION

    CPT 81377: HLA Class II Allele Group Typing, Low/Intermediate Resolution

    CPT-81378-HLA-HIGH-RESOLUTION-MOLECULAR-TYPING-CLASS-I-II-DRB1

    CPT 81378: High-Resolution HLA Class I and II Typing

    CPT-81379-HLA-CLASS-I-HIGH-RESOLUTION-TYPING

    CPT 81379: HLA Class I High-Resolution Molecular Typing

    CPT-81380-HLA-HIGH-RESOLUTION-CLASS-I-TYPING

    CPT 81380: HLA High-Resolution Molecular Typing, One Class I Locus

    Showing 1–10 of 13

    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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