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

CPT code 81107 represents a laboratory technical procedure for genotyping the two common alleles of Human Platelet Antigen 3 (HPA–3/I843S). This molecular diagnostic test identifies platelet antigen variants that can be relevant for alloimmunization, transfusion compatibility, and certain maternal–fetal platelet disorders. As genetic testing expands, accurate coding for targeted allele analysis informs clinical workflows, lab reporting, and payer adjudication nationwide.

Key payers covered in this analysis include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. The publication outlines how CPT code 81107 is used across clinical laboratories, typical sites of service, and the clinical contexts prompting HPA–3 testing.

Readers will learn operational and policy-relevant details including common service settings, clinical indications for HPA–3 genotyping, and the kinds of benchmarks and policy updates to monitor for molecular diagnostic codes. Where specific data elements are not provided in the source input, the text notes that those items are not available. The summary focuses on the code’s clinical purpose, payer landscape, and the practical implications for laboratory services and billing workflows in a national context.

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Billing Code Overview

CPT code 81107 describes a molecular diagnostic laboratory test that identifies the two common alleles of Human Platelet Antigen 3 (HPA–3), also known as I843S. The procedure is performed by a laboratory analyst who conducts the technical component of the genetic analysis using a biological specimen such as blood or amniotic fluid.

Service Type: Genetic testing / molecular diagnostic technical component

Typical Site of Service: Clinical laboratory or hospital laboratory

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

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Get alerted when payer policies referencing 81107 are released or updated.

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Billing Code Overview

Service Type: Genetic testing / molecular diagnostic technical component

Typical Site of Service: Clinical laboratory or hospital laboratory

Clinical & Coding Specifications

Clinical Context

A 32-year-old pregnant woman is referred for thrombocytopenia workup after routine prenatal labs identify low platelet counts and a family history of neonatal alloimmune thrombocytopenia (NAIT). The obstetrician collects a maternal peripheral blood specimen; the laboratory performs 81107 testing to genotype the two common alleles of Human Platelet Antigen 3 (HPA‑3, I843S) to determine maternal and, if available, paternal or fetal antigen status. Results guide risk assessment for NAIT, donor selection for platelet transfusion, and prenatal counseling. Typical workflow: specimen collection (mother, father, or amniotic fluid), accessioning, DNA extraction, allele‑specific PCR or sequencing for HPA‑3, analytic validation, result verification by a clinical laboratory scientist, and final reporting to the ordering obstetrician, maternal‑fetal medicine specialist, or transfusion service. Typical sites of service include hospital clinical molecular laboratories, reference genetic testing laboratories, and maternal‑fetal medicine outpatient clinics coordinating specimen shipment. Testing is commonly ordered when maternal immunization against platelet antigens is suspected, in neonatal thrombocytopenia evaluation, or prior to platelet transfusion planning for sensitized patients.

Coding Specifications

Modifier	Description	When to Use
`26`	Professional component	Use when only the professional interpretation/reporting component is billed separately from the technical lab work.
`TC`	Technical component	Use when only the technical component (laboratory processing and analysis) is billed.
`90`	Reference (outside) laboratory	Use when the testing is performed by an outside reference laboratory and billed by the referring provider.
`59`	Distinct procedural service	Use when another unrelated service is performed the same day and documentation supports separate reporting.
`52`	Reduced services	Use when the test is partially reduced or not completed as originally described.
`53`	Discontinued procedure	Use if testing was started but discontinued for patient‑related or technical reasons prior to completion.
`59`	Distinct procedural service	Use when another unrelated service is performed the same day and documentation supports separate reporting.
`90`	Reference (outside) laboratory	Use when the testing is performed by an outside reference laboratory and billed by the referring provider.
`QX`	CLIA waived test(s) performed by non‑physician	Rare for molecular genotyping; use only if applicable under payer rules when a non‑physician performs testing in a waived setting.
`QY`	CLIA moderate/high complexity performed by non‑physician under physician supervision	Use when applicable for moderate/high complexity testing performed under appropriate supervision.
`26`	Professional component	Use when only the professional interpretation/reporting component is billed separately from the technical lab work.

Taxonomy Code	Specialty	Notes
207RG0100X	Clinical Molecular Genetics Laboratory	Labs that perform molecular platelet antigen genotyping.
207L00000X	Clinical Laboratory	Hospital or reference clinical labs performing genetic testing.
2084P0200X	Maternal-Fetal Medicine	Specialists ordering prenatal platelet antigen genotyping for NAIT risk.
207RC0000X	Pathology	Pathologists overseeing molecular diagnostic testing in hospital labs.
207K00000X	Transfusion Medicine	Specialists coordinating donor selection and platelet compatibility.

Related Diagnoses

ICD-10 Code	Description	Clinical Relevance
`D69.5`	Secondary thrombocytopenia	Relevant when maternal or neonatal thrombocytopenia prompts HPA genotyping to evaluate alloimmune causes.
`D69.6`	Thrombocytopenia, unspecified	Used when thrombocytopenia is documented and platelet antigen genotyping is ordered as part of evaluation.
`Z34.90`	Encounter for supervision of normal pregnancy, unspecified trimester	Genotyping may be performed during prenatal care when NAIT risk is assessed due to history.
`O36.5XX0`	Maternal care for known or suspected fetal abnormality and damage, unspecified, not applicable or unspecified	Used when fetal thrombocytopenia or alloimmune disease is suspected and HPA testing is ordered.
`Z31.419`	Encounter for genetic testing for carrier status, unspecified	Used when parental platelet antigen carrier status is evaluated prior to or during pregnancy.

Related CPT Codes

CPT Code	Description	Relationship to This Procedure
`81479`	Unlisted molecular pathology procedure	Used if HPA genotyping requires a unique method not covered by specific codes; may be used for nonstandard assays.
`81105`	HPA-1 genotyping; common allele analysis	Performed alongside `81107` when a broader platelet antigen profile (HPA-1 and HPA-3) is needed for NAIT workup.
`81225`	HLA typing, specific allele or group (example)	Performed as complementary compatibility testing for platelet transfusion planning in sensitized patients.
`86356`	Antibody identification (platelet antibody)	Performed to detect maternal anti‑platelet antibodies when alloimmunization is suspected.
`36415`	Collection of venous blood by venipuncture	Commonly performed prior to genotyping to obtain the sample for `81107`.

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

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

CPT 81106: HPA-2 (T145M) Genetic Allele Analysis

CPT-81108-HPA-4-R143Q-GENOTYPING

CPT 81108: HPA-4 (R143Q) Genotyping, Technical Component

CPT-81109-HPA-5-K505E-GENETIC-ANALYSIS

CPT 81109: HPA-5 (K505E) Genetic Analysis

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) Allele Analysis, Laboratory Technical Component

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

CPT 81112: HPA-15 (S682Y) Genetic Analysis

CPT-81120-IDH1-MOLECULAR-DIAGNOSTIC-TEST

CPT 81120: IDH1 Molecular Diagnostic Test

CPT-81121-IDH2-MOLECULAR-DIAGNOSTIC-TEST

CPT 81121: IDH2 (NADP+) Molecular Diagnostic Test

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

CPT 81161: DMD Gene Deletion/Duplication Analysis

Showing 1–10 of 199

References

1.CPT® Codes and Descriptions. AAPC. Retrieved Jul 29, 2026.
2.HCPCS Quarterly Update. Centers for Medicare & Medicaid Services (CMS). Retrieved Jul 29, 2026.
3.ICD-10-CM Full Code List. Centers for Medicare & Medicaid Services (CMS). Retrieved Jul 29, 2026.

Published by

Trek Health powers OpenPayer with a leading commercial payer intelligence platform, seamlessly converting fragmented payer data into actionable insights for provider organizations.

Trek Health ingests and normalizes Transparency in Coverage data and payer policy updates to give provider organizations a clear view of how commercial reimbursement behaves across markets, payers, and services. Our platform transforms raw payer disclosures into structured intelligence that supports contract evaluation, payer negotiations, and service line strategy. By combining market benchmarks with ongoing policy visibility, Trek helps teams identify variability, risk, and opportunity in commercial reimbursement. The result is faster insight, stronger negotiating positions, and more informed financial decisions.

Clinical & Coding Specifications

Clinical Context

Coding Specifications

Modifier	Description	When to Use
`26`	Professional component	Use when only the professional interpretation/reporting component is billed separately from the technical lab work.
`TC`	Technical component	Use when only the technical component (laboratory processing and analysis) is billed.
`90`	Reference (outside) laboratory	Use when the testing is performed by an outside reference laboratory and billed by the referring provider.
`59`	Distinct procedural service	Use when another unrelated service is performed the same day and documentation supports separate reporting.
`52`	Reduced services	Use when the test is partially reduced or not completed as originally described.
`53`	Discontinued procedure	Use if testing was started but discontinued for patient‑related or technical reasons prior to completion.
`59`	Distinct procedural service	Use when another unrelated service is performed the same day and documentation supports separate reporting.
`90`	Reference (outside) laboratory	Use when the testing is performed by an outside reference laboratory and billed by the referring provider.
`QX`	CLIA waived test(s) performed by non‑physician	Rare for molecular genotyping; use only if applicable under payer rules when a non‑physician performs testing in a waived setting.
`QY`	CLIA moderate/high complexity performed by non‑physician under physician supervision	Use when applicable for moderate/high complexity testing performed under appropriate supervision.
`26`	Professional component	Use when only the professional interpretation/reporting component is billed separately from the technical lab work.

Taxonomy Code	Specialty	Notes
207RG0100X	Clinical Molecular Genetics Laboratory	Labs that perform molecular platelet antigen genotyping.
207L00000X	Clinical Laboratory	Hospital or reference clinical labs performing genetic testing.
2084P0200X	Maternal-Fetal Medicine	Specialists ordering prenatal platelet antigen genotyping for NAIT risk.
207RC0000X	Pathology	Pathologists overseeing molecular diagnostic testing in hospital labs.
207K00000X	Transfusion Medicine	Specialists coordinating donor selection and platelet compatibility.

Related Diagnoses

ICD-10 Code	Description	Clinical Relevance
`D69.5`	Secondary thrombocytopenia	Relevant when maternal or neonatal thrombocytopenia prompts HPA genotyping to evaluate alloimmune causes.
`D69.6`	Thrombocytopenia, unspecified	Used when thrombocytopenia is documented and platelet antigen genotyping is ordered as part of evaluation.
`Z34.90`	Encounter for supervision of normal pregnancy, unspecified trimester	Genotyping may be performed during prenatal care when NAIT risk is assessed due to history.
`O36.5XX0`	Maternal care for known or suspected fetal abnormality and damage, unspecified, not applicable or unspecified	Used when fetal thrombocytopenia or alloimmune disease is suspected and HPA testing is ordered.
`Z31.419`	Encounter for genetic testing for carrier status, unspecified	Used when parental platelet antigen carrier status is evaluated prior to or during pregnancy.

Related CPT Codes

CPT Code	Description	Relationship to This Procedure
`81479`	Unlisted molecular pathology procedure	Used if HPA genotyping requires a unique method not covered by specific codes; may be used for nonstandard assays.
`81105`	HPA-1 genotyping; common allele analysis	Performed alongside `81107` when a broader platelet antigen profile (HPA-1 and HPA-3) is needed for NAIT workup.
`81225`	HLA typing, specific allele or group (example)	Performed as complementary compatibility testing for platelet transfusion planning in sensitized patients.
`86356`	Antibody identification (platelet antibody)	Performed to detect maternal anti‑platelet antibodies when alloimmunization is suspected.
`36415`	Collection of venous blood by venipuncture	Commonly performed prior to genotyping to obtain the sample for `81107`.

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

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

CPT 81106: HPA-2 (T145M) Genetic Allele Analysis

CPT-81108-HPA-4-R143Q-GENOTYPING

CPT 81108: HPA-4 (R143Q) Genotyping, Technical Component

CPT-81109-HPA-5-K505E-GENETIC-ANALYSIS

CPT 81109: HPA-5 (K505E) Genetic Analysis

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) Allele Analysis, Laboratory Technical Component

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

CPT 81112: HPA-15 (S682Y) Genetic Analysis

CPT-81120-IDH1-MOLECULAR-DIAGNOSTIC-TEST

CPT 81120: IDH1 Molecular Diagnostic Test

CPT-81121-IDH2-MOLECULAR-DIAGNOSTIC-TEST

CPT 81121: IDH2 (NADP+) Molecular Diagnostic Test

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

CPT 81161: DMD Gene Deletion/Duplication Analysis

Showing 1–10 of 199

References

1.CPT® Codes and Descriptions. AAPC. Retrieved Jul 29, 2026.
2.HCPCS Quarterly Update. Centers for Medicare & Medicaid Services (CMS). Retrieved Jul 29, 2026.
3.ICD-10-CM Full Code List. Centers for Medicare & Medicaid Services (CMS). Retrieved Jul 29, 2026.

Published by

Trek Health powers OpenPayer with a leading commercial payer intelligence platform, seamlessly converting fragmented payer data into actionable insights for provider organizations.

OpenPayer

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

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Billing Code Overview

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OpenPayer

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

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Billing Code Overview

Clinical & Coding Specifications

Clinical Context

Coding Specifications

Related Diagnoses

Related CPT Codes

Related Codes

References

Clinical & Coding Specifications

Clinical Context

Coding Specifications

Related Diagnoses

Related CPT Codes

Related Codes

References