CPT 81105 HPA‑1 Genotyping Reimbursement | OpenPayer

Summary & Overview

CPT 81105: HPA-1 (CD61/ITGB3) Platelet Antigen Genotyping

CPT code 81105 represents a molecular diagnostic laboratory test that determines the genotype of the two common alleles of Human Platelet Antigen 1 (HPA–1), also referenced as CD61 or ITGB3. This platelet antigen genotyping assay has clinical implications for transfusion compatibility, platelet refractoriness evaluation, and prenatal assessment of alloimmune platelet disorders. Nationally, such targeted genetic testing supports precision transfusion management and maternal-fetal risk assessment.

Key payers discussed include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. The publication provides a concise overview of coverage and billing practice trends across major national payers and Medicare, with attention to clinical context and coding implications.

Readers will find a clear description of the clinical purpose and typical service settings for CPT code 81105, an outline of common modifiers associated with laboratory services, and guidance on what benchmark and policy items are covered in the full publication. The document clarifies where data are available and flags areas where input did not supply specific payer policy details. This summary is intended to orient laboratory billing staff, clinical geneticists, and policy analysts to the code's clinical role and the scope of the accompanying analysis.

AetnaBlue Cross Blue ShieldCigna HealthUnitedHealthcareMedicare81105CPTmolecular-diagnosticsplatelet-antigen-genotypingHPA-1ITGB3clinical-laboratorygenetic-testing

Billing Code Overview

CPT code 81105 describes a laboratory technical procedure in which a lab analyst performs genetic analysis of the two common alleles of Human Platelet Antigen 1 (HPA–1), also known as CD61 or ITGB3, using a biologic specimen such as blood or amniotic fluid. This service is a molecular diagnostic test focused on platelet antigen genotyping.

Service type: Molecular diagnostic / Clinical laboratory procedure

Typical site of service: Clinical laboratory or hospital laboratory; specimens are commonly collected in outpatient phlebotomy settings, inpatient care areas, or prenatal sample collection locations.

Clinical & Coding Specifications

Clinical Context

A 29-year-old pregnant woman with a prior history of neonatal alloimmune thrombocytopenia (NAIT) in a previous pregnancy is referred to maternal-fetal medicine for fetal risk assessment. The obstetrician orders 81105 to determine the maternal and paternal Human Platelet Antigen 1 (HPA‑1) genotype using maternal blood and paternal blood (or amniotic fluid when fetal genotype is required). The laboratory receives the specimen, performs DNA extraction, and runs targeted genotyping for HPA‑1 (ITGB3/CD61) alleles. Results guide counseling about fetal risk for HPA‑1 incompatibility, monitoring strategy (serial ultrasounds, fetal platelet testing if indicated), and peripartum planning for delivery and neonatal platelet support.

Service Type: Molecular diagnostic genotyping (technical component laboratory test).
Typical Site of Service: Clinical molecular laboratory or hospital reference laboratory; specimens collected in ambulatory clinic, obstetrics office, or inpatient setting.
Typical Patient Scenario: Pregnant patient with prior infant affected by alloimmune thrombocytopenia, a partner with unknown HPA‑1 status, family history of platelet antigen incompatibility, or cases where neonatal thrombocytopenia risk assessment is required prior to delivery.

Coding Specifications

Modifier	Description

CPT 81174: Targeted Androgen Receptor (AR) Gene Variant Analysis

CPT-81342-TCELL-RECEPTOR-GAMMA-CLONALITY-ASSAY

CPT 81342: T‑cell Receptor Gamma Clonality Assay

CPT-81329-SMN1-DELETION-ANALYSIS-GENETIC-TESTING

CPT 81329: SMN1 Deletion Analysis; SMN2 Analysis as Indicated

CPT-81166-BRCA1-LARGE-GENE-REARRANGEMENT-ANALYSIS

CPT 81166: BRCA1 Large Gene Rearrangement Analysis, Technical Component

CPT-81315-PML-RARALPHA-FUSION-DETECTION-QUANTIFICATION

CPT 81315: PML/RARalpha (t(15;17)) Fusion Detection and Quantification

CPT-81164-BRCA1-BRCA2-LARGE-REARRANGEMENT-ANALYSIS

CPT 81164: BRCA1/BRCA2 Large Rearrangement Analysis

CPT-81192-NTRK2-TRANSLOCATION-ANALYSIS-FFPE

CPT 81192: NTRK2 Translocation Analysis in Solid Tumors

CPT-81312-PABPN1-GENE-EXPANSION-DETECTION

CPT 81312: PABPN1 Gene Expansion Detection

CPT-81205-BCKDHB-GENE-TESTING-TECHNICAL-LAB

CPT 81205: BCKDHB Gene Testing, Technical Laboratory Test

CPT-81352-TP53-TARGETED-SEQUENCING-LI-FRAUMENI

CPT 81352: Targeted TP53 Gene Sequencing for Li–Fraumeni Syndrome

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Taxonomy Code	Specialty	Notes
`207Q00000X`	Clinical Molecular Genetics Laboratory	Labs performing molecular genotyping and interpretation.
`207K00000X`	Clinical Laboratory	Hospital or reference clinical laboratory performing technical testing.
`207L00000X`	Pathology and Laboratory Medicine	Pathologists who oversee molecular diagnostic testing and result validation.
`208D00000X`	Maternal-Fetal Medicine	Specialists who order HPA genotyping for pregnancy risk assessment.
`207P00000X`	Diagnostic Molecular Biology	Laboratory scientists/diagnostic molecular biologists conducting genotyping assays.

Related Diagnoses

ICD-10 Code	Description	Clinical Relevance
`O36.821`	Maternal care for known or suspected fetal problems, specifically isoimmunization or alloimmune thrombocytopenia	Primary indication for HPA‑1 genotyping in pregnancy to evaluate fetal risk for alloimmune thrombocytopenia (NAIT).
`D69.5`	Secondary thrombocytopenia	Relevant when assessing causes of neonatal or maternal thrombocytopenia and to identify alloimmune causes.
`Z84.81`	Family history of hematological disorder	Family history prompting parental genotyping for platelet antigens.
`P61.0`	Neonatal alloimmune thrombocytopenia	Directly related to HPA incompatibility; genotyping guides neonatal risk assessment and management.
`Z31.430`	Encounter for genetic counseling related to pregnancy	Reflects genetic counseling visits that often accompany HPA genotyping and result disclosure.

Related CPT Codes

CPT Code	Description	Relationship to This Procedure
`81225`	Factor V (F5) gene analysis, common variants (e.g., Factor V Leiden)	Not directly related but an example of targeted DNA variant analysis performed in the same molecular laboratory workflow; may be ordered alongside thrombosis-related testing in pregnancy evaluation.
`81479`	Unlisted molecular pathology procedure	Used when a specific molecular assay does not have a dedicated CPT; not typical for HPA‑1 but available for novel or atypical assays.
`80500`	Specimen handling and other services (example lab code group)	Represents ancillary laboratory services such as specimen processing that accompany genotyping tests (coding varies by payer).
`0000F`	(Note: placeholder for panel or counseling codes)	Genetic counseling and result interpretation by maternal-fetal medicine or genetics may accompany genotyping; counseling itself is documented separately and billed under appropriate E/M or counseling codes.

`26`	Professional component	Use when reporting the professional (interpretive) component separately if applicable and payable separately from the laboratory technical component.
`TC`	Technical component	Use when reporting only the technical component performed by the lab performing the genotyping.
`90`	Reference (outside) laboratory	Use when the service was performed by an outside laboratory and billing is by the ordering provider who forwards testing.
`59`	Distinct procedural service	Use when another unrelated procedure or laboratory service is billed on same day and documentation supports distinct service.
`90`	Reference (duplicate noted)	(See above) Note: `90` already listed; use per payer rules if external lab performed testing.
`52`	Reduced services	Use when specimen quantity or test elements were limited and test performed was reduced.
`53`	Discontinued procedure	Use if testing was started but discontinued prior to completion for reasons documented.
`78`	Unplanned return to operating/procedure room	Rarely applicable; use only if an unexpected return for a separate invasive procedure necessitated additional testing tied to that event.
`22`	Increased procedural services	Use when work required is substantially greater than typical for the test (documented justification).
`90`	(Alternate payers may require)	Some payers accept `90` to indicate outside lab; include per payer guidance.
`59`	(Distinct service emphasis)	Use with caution; follow local payer edits for lab services.

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