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

CPT code 81107 describes a laboratory molecular diagnostic test in which the technical component analyzes the genes for the two common alleles of Human Platelet Antigen 3 (HPA‑3, also called I843S) using a specimen such as blood or amniotic fluid; service type: genetic/hematology molecular diagnostic assay (technical component); typical site of service: clinical laboratory or hospital lab where the technical processing and analysis of the specimen are performed.

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

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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.

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`.

Related Modifiers

5 rows

Modifier	Description	When to Use
26	Modifier 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…
90	Modifier ‑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…
59	Modifier 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…
52	Modifier ‑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…
53	Modifier 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	Specialty	Notes
207RG0100X	Gastroenterology Physician	An internist who specializes in diagnosis and treatment of diseases of the digestive organs including the stomach, bowels, liver and gallbladder. This…
207L00000X	Anesthesiology Physician	An anesthesiologist is trained to provide pain relief and maintenance, or restoration, of a stable condition during and immediately following an opera…
207RC0000X	Cardiovascular Disease Physician	An internist who specializes in diseases of the heart and blood vessels and manages complex cardiac conditions such as heart attacks and life-threaten…
207K00000X	Allergy & Immunology Physician	An allergist-immunologist is trained in evaluation, physical and laboratory diagnosis, and management of disorders involving the immune system. Select…
261QM1100X	Military/U.S. Coast Guard Outpatient Clinic/Center	The Defense Health Program or U.S. Coast Guard funded "fixed" facilities or distinct parts of a facility, providing outpatient medical and dental serv…
282NC0060X	Critical Access Hospital	Hospitals · General Acute Care Hospital
225600000X	Dance Therapist	The dance therapist, sometimes called a movement therapist, focuses on rhythmic body movements as a medium of physical and psychological change. Dance…
2080P0202X	Pediatric Cardiology Physician	A pediatric cardiologist provides comprehensive care to patients with cardiovascular problems. This specialist is skilled in selecting, performing and…

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-81108-HPA-4-R143Q-GENOTYPING

CPT 81108: HPA-4 (R143Q) Genotyping

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

CPT 81109: HPA-5 (K505E) Genotyping Test

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

Frequently Asked Questions

References

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.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.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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Clinical & Coding Specifications

Clinical Context

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`.

Related Modifiers

5 rows

Modifier	Description	When to Use
26	Modifier 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…
90	Modifier ‑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…
59	Modifier 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…
52	Modifier ‑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…
53	Modifier 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	Specialty	Notes
207RG0100X	Gastroenterology Physician	An internist who specializes in diagnosis and treatment of diseases of the digestive organs including the stomach, bowels, liver and gallbladder. This…
207L00000X	Anesthesiology Physician	An anesthesiologist is trained to provide pain relief and maintenance, or restoration, of a stable condition during and immediately following an opera…
207RC0000X	Cardiovascular Disease Physician	An internist who specializes in diseases of the heart and blood vessels and manages complex cardiac conditions such as heart attacks and life-threaten…
207K00000X	Allergy & Immunology Physician	An allergist-immunologist is trained in evaluation, physical and laboratory diagnosis, and management of disorders involving the immune system. Select…
261QM1100X	Military/U.S. Coast Guard Outpatient Clinic/Center	The Defense Health Program or U.S. Coast Guard funded "fixed" facilities or distinct parts of a facility, providing outpatient medical and dental serv…
282NC0060X	Critical Access Hospital	Hospitals · General Acute Care Hospital
225600000X	Dance Therapist	The dance therapist, sometimes called a movement therapist, focuses on rhythmic body movements as a medium of physical and psychological change. Dance…
2080P0202X	Pediatric Cardiology Physician	A pediatric cardiologist provides comprehensive care to patients with cardiovascular problems. This specialist is skilled in selecting, performing and…

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-81108-HPA-4-R143Q-GENOTYPING

CPT 81108: HPA-4 (R143Q) Genotyping

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

CPT 81109: HPA-5 (K505E) Genotyping Test

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

Frequently Asked Questions

References

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.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.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.

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

Sign up for cpt 81107 policy alerts

OpenPayer

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

Sign up for cpt 81107 policy alerts

Clinical & Coding Specifications

Clinical Context

Related CPT Codes

Related Modifiers

Related Provider Taxonomies

Related Codes

References

Clinical & Coding Specifications

Clinical Context

Related CPT Codes

Related Modifiers

Related Provider Taxonomies

Related Codes

References

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

Sign up for cpt 81107 policy alerts

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

Sign up for cpt 81107 policy alerts

Clinical & Coding Specifications

Clinical Context

Related CPT Codes

Related Modifiers

Related Provider Taxonomies

Related Codes

What does CPT 81107 describe?

In what clinical situations is HPA‑3 genotyping commonly ordered?

Which specimens and workflow steps are associated with this test?

What related CPT codes might be billed alongside or instead of 81107?

What ICD‑10 diagnoses are relevant to support ordering or billing for this test?

References

Clinical & Coding Specifications

Clinical Context

Related CPT Codes

Related Modifiers

Related Provider Taxonomies

Related Codes

What does CPT 81107 describe?

In what clinical situations is HPA‑3 genotyping commonly ordered?

Which specimens and workflow steps are associated with this test?

What related CPT codes might be billed alongside or instead of 81107?

What ICD‑10 diagnoses are relevant to support ordering or billing for this test?

References