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    v1.0.30
    OpenPayerBilling CodesGenetic Analysis ProceduresCPT cpt-81109-hpa-5-k505e-genetic-analysis
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    CPT 81109: HPA-5 (K505E) Genotyping Test

    CPT code 81109 describes a laboratory genotyping test in which a lab analyst performs the technical procedures to analyze the two common alleles of Human Platelet Antigen 5 (HPA‑5 / K505E) using a specimen such as blood or amniotic fluid; service type is molecular diagnostic / hematology genetic testing, and the typical site of service is a clinical laboratory or hospital lab performing molecular genetics assays.

    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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    Clinical & Coding Specifications

    Clinical Context

    A typical patient is a pregnant woman or an adult being evaluated for alloimmune thrombocytopenia risk or transfusion compatibility. A prenatal obstetrician orders 81109 when a patient has a prior history of neonatal alloimmune thrombocytopenia (NAIT), unexplained fetal thrombocytopenia, a previous infant with intracranial hemorrhage, or when the partner’s or fetus’s platelet antigen status is needed for risk assessment. The clinical workflow begins with collection of a maternal peripheral blood sample (or amniotic fluid when fetal testing is indicated) and submission to a molecular diagnostics laboratory. The laboratory analyst performs DNA-based genotyping to determine the allelic variants of Human Platelet Antigen 5 (HPA–5, K505E). Results are reported to the ordering clinician and used to counsel regarding recurrence risk, guide monitoring in pregnancy, plan for peripartum management, and inform transfusion or platelet selection decisions for the mother or neonate.

    Related CPT Codes

    CPT CodeDescriptionRelationship to This Procedure
    81479Unlisted molecular pathology procedureUsed when a specific genetic test does not have an assigned code; sometimes used for novel or expanded platelet antigen panels alongside 81109.
    88237Flow cytometry, DNA analysis, probe-based (for platelet antigen surface testing)May be used when platelet antigen expression testing is performed by flow cytometry rather than genotyping; complementary to 81109 when phenotype confirmation is required.
    36415Collection of venous blood by venipunctureOften performed immediately prior to 81109 specimen submission for DNA-based HPA–5 testing.
    0000FMaternal cell-free DNA fetal testing (placeholder)In workflows where fetal genotyping is pursued noninvasively or via amniocentesis, relevant prenatal molecular tests may be ordered in coordination with 81109 results.
    89240Amniotic fluid genetic studies (processing)When fetal testing for HPA alleles is performed on amniotic fluid, specimen processing and genetic analysis codes are part of the workflow.

    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…
    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…
    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 Code
    207QS0010X
    225XR0403X
    207XS0114X
    152WS0006X
    163WC1400X
    331L00000X
    163WX0200X
    2080H0002X

    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-81105-HPA-1-PLATELET-ANTIGEN-1-GENOTYPING-ITGB3-CD61

    CPT 81105: HPA-1 (ITGB3/CD61) Genotyping, Technical Component

    CPT-81106-HPA-2-T145M-GENETIC-ALLELE-ANALYSIS

    CPT 81106: HPA-2 (T145M) Platelet Antigen Genotyping

    CPT-81107-HPA-3-GENETIC-ANALYSIS-TECHNICAL-COMPONENT

    CPT 81107: HPA‑3 (I843S) Platelet Antigen Genotyping

    CPT-81108-HPA-4-R143Q-GENOTYPING

    CPT 81108: HPA-4 (R143Q) Genotyping

    CPT-81110-HPA-6-R489Q-GENOTYPING

    CPT 81110: HPA-6 (R489Q) Genotyping, Technical Component

    CPT-81111-HPA-9-V837M-ALLELE-ANALYSIS

    CPT 81111: HPA-9 (V837M) Genotyping, Technical Test

    CPT-81112-HPA-15-GENETIC-ANALYSIS-S682Y

    CPT 81112: HPA-15 (S682Y) Platelet Antigen Genotyping

    CPT-81120-IDH1-MOLECULAR-DIAGNOSTIC-TEST

    CPT 81120: IDH1 Mutation Detection, Technical Component

    CPT-81121-IDH2-MOLECULAR-DIAGNOSTIC-TEST

    CPT 81121: IDH2 Mutation Detection, Technical Component

    CPT-81161-DMD-GENE-DELETION-DUPLICATION-ANALYSIS

    CPT 81161: Dystrophin (DMD) Gene Deletion/Duplication Analysis

    Showing 1–10 of 199

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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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