Find policies, billing codes, payers, states, and providers

CPT 81373: HLA Class I Low/Intermediate Resolution Molecular Test

CPT code 81373 covers a laboratory molecular test that performs low- or intermediate-resolution typing of human leukocyte antigen (HLA) genes for a single Class I locus. This code captures the technical component of HLA Class I genotyping performed using molecular techniques. HLA testing is critical for organ and stem cell transplantation compatibility, donor selection, and certain immunogenetic evaluations, making accurate coding and billing important for patient matching and laboratory reimbursement nationally.

Key payers addressed in this analysis include Aetna, Blue Cross Blue Shield, Cigna Health, UnitedHealthcare, and Medicare. The publication outlines typical payment and coverage considerations across major national payers, where available, and identifies common clinical contexts in which CPT code 81373 is used.

Readers will find an overview of the code’s clinical purpose and service setting, payer coverage scope, common modifiers and billing considerations, and related procedural context. Where specific benchmark or policy data is not provided in the input, the text notes that information is not available. The piece is written for a national audience interested in clinical coding, laboratory services, and payer coverage patterns for HLA Class I molecular testing.

Customize your policy alerts

Sign up for cpt 81373 policy alerts

Get alerted when payer policies referencing 81373 are released or updated.

Monitor payer policy activity

Receive email alerts as soon as relevant payer policies are published or updated.

Billing Code Overview

CPT code 81373 describes a technical laboratory assay that performs a low- or intermediate-resolution assessment of human leukocyte antigen (HLA) genes for one Class I locus using molecular techniques. The service involves laboratory processing and analysis of patient specimens to determine HLA Class I genotypes at a resolution level used for transplantation matching, donor screening, or disease association testing.

Service type: Laboratory molecular diagnostic test (technical component)

Typical site of service: Clinical laboratory or hospital laboratory

Data not available in the input.

Find policies, billing codes, payers, states, and providers

CPT 81373: HLA Class I Low/Intermediate Resolution Molecular Test

Customize your policy alerts

Sign up for cpt 81373 policy alerts

Get alerted when payer policies referencing 81373 are released or updated.

Monitor payer policy activity

Receive email alerts as soon as relevant payer policies are published or updated.

Billing Code Overview

Service type: Laboratory molecular diagnostic test (technical component)

Typical site of service: Clinical laboratory or hospital laboratory

Data not available in the input.

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.

Coding Specifications

Modifier	Description	When to Use
`00`	No modifier	Use when no other modifier applies and service is billed normally
`26`	Professional component	Use when reporting only the professional (interpretation) component if applicable in split billing arrangements
`TC`	Technical component	Use when reporting only the technical laboratory processing and testing component (common for lab analysts)
`59`	Distinct procedural service	Use when an unrelated distinct laboratory procedure is performed on the same day and needs to be identified
`90`	Reference (outside) laboratory	Use when the testing is performed by an outside reference laboratory and billed by another entity
`91`	Repeat clinical diagnostic laboratory test	Use when the same test is repeated on a separate specimen to verify results
`52`	Reduced services	Use when the test is partially reduced or not fully completed for clinical reasons
`53`	Discontinued procedure	Use if testing was started but discontinued prior to completion for valid clinical reasons
`59`	Distinct procedural service	Use to indicate a separate service when multiple laboratory procedures are billed together (listed to emphasize relevance)
`90`	Reference (outside) laboratory	Use to indicate performance by a reference lab (listed to emphasize relevance)

Taxonomy Code	Specialty	Notes
207Q00000X	Clinical Molecular Genetics	Laboratories and providers performing molecular HLA testing
2080P0002X	Pathology	Molecular pathology and clinical laboratory directors who oversee testing
207L00000X	Clinical Laboratory	Medical laboratory scientists and laboratory directors involved in testing
207RC0000X	Anatomic and Clinical Pathology	Pathologists providing interpretation and consultative services

Related Diagnoses

ICD-10 Code	Description	Clinical Relevance
`Z94.0`	Kidney transplant status	HLA Class I typing is used for donor–recipient matching and post-transplant immunologic assessment
`Z94.83`	Bone marrow transplant status	HLA typing is essential for hematopoietic stem cell donor selection and compatibility
`Z15.01`	Genetic susceptibility to malignant neoplasm of breast	HLA testing may be performed in research or specialized immunogenetics contexts (limited)
`D72.8`	Other specified disorders of white blood cells	Immunogenetic evaluation, including HLA typing, can be part of workup for immune-related hematologic issues
`Z48.21`	Encounter for aftercare following kidney transplant	Post-transplant monitoring may include HLA-related testing for graft surveillance

Related CPT Codes

CPT Code	Description	Relationship to This Procedure
`81373`	HLA 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
`81374`	HLA typing; low or intermediate resolution, one class II locus	Commonly ordered alongside Class I testing when extended HLA typing (Class II) is needed for transplantation
`81376`	HLA typing; high resolution, one class I or class II locus	May be ordered when higher resolution allele-level typing is required after initial low/intermediate results
`86850`	Tissue typing set including lymphocytotoxic testing	Historical or complementary serologic tissue typing that may be performed in transplant evaluation
`0022U`	HLA 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

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

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

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

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

CPT 81372: HLA Class I Low/Intermediate-Resolution Molecular Typing

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

CPT 81374: HLA Class I Low/Intermediate-Resolution Testing

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 Typing, Low/Intermediate-Resolution Technical

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 Molecular Typing

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

CPT 81379: High-Resolution HLA Class I Typing

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

CPT 81380: High-Resolution HLA Class I Molecular Typing

Showing 1–10 of 13

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
`00`	No modifier	Use when no other modifier applies and service is billed normally
`26`	Professional component	Use when reporting only the professional (interpretation) component if applicable in split billing arrangements
`TC`	Technical component	Use when reporting only the technical laboratory processing and testing component (common for lab analysts)
`59`	Distinct procedural service	Use when an unrelated distinct laboratory procedure is performed on the same day and needs to be identified
`90`	Reference (outside) laboratory	Use when the testing is performed by an outside reference laboratory and billed by another entity
`91`	Repeat clinical diagnostic laboratory test	Use when the same test is repeated on a separate specimen to verify results
`52`	Reduced services	Use when the test is partially reduced or not fully completed for clinical reasons
`53`	Discontinued procedure	Use if testing was started but discontinued prior to completion for valid clinical reasons
`59`	Distinct procedural service	Use to indicate a separate service when multiple laboratory procedures are billed together (listed to emphasize relevance)
`90`	Reference (outside) laboratory	Use to indicate performance by a reference lab (listed to emphasize relevance)

Taxonomy Code	Specialty	Notes
207Q00000X	Clinical Molecular Genetics	Laboratories and providers performing molecular HLA testing
2080P0002X	Pathology	Molecular pathology and clinical laboratory directors who oversee testing
207L00000X	Clinical Laboratory	Medical laboratory scientists and laboratory directors involved in testing
207RC0000X	Anatomic and Clinical Pathology	Pathologists providing interpretation and consultative services

Related Diagnoses

ICD-10 Code	Description	Clinical Relevance
`Z94.0`	Kidney transplant status	HLA Class I typing is used for donor–recipient matching and post-transplant immunologic assessment
`Z94.83`	Bone marrow transplant status	HLA typing is essential for hematopoietic stem cell donor selection and compatibility
`Z15.01`	Genetic susceptibility to malignant neoplasm of breast	HLA testing may be performed in research or specialized immunogenetics contexts (limited)
`D72.8`	Other specified disorders of white blood cells	Immunogenetic evaluation, including HLA typing, can be part of workup for immune-related hematologic issues
`Z48.21`	Encounter for aftercare following kidney transplant	Post-transplant monitoring may include HLA-related testing for graft surveillance

Related CPT Codes

CPT Code	Description	Relationship to This Procedure
`81373`	HLA 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
`81374`	HLA typing; low or intermediate resolution, one class II locus	Commonly ordered alongside Class I testing when extended HLA typing (Class II) is needed for transplantation
`81376`	HLA typing; high resolution, one class I or class II locus	May be ordered when higher resolution allele-level typing is required after initial low/intermediate results
`86850`	Tissue typing set including lymphocytotoxic testing	Historical or complementary serologic tissue typing that may be performed in transplant evaluation
`0022U`	HLA 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

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

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

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

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

CPT 81372: HLA Class I Low/Intermediate-Resolution Molecular Typing

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

CPT 81374: HLA Class I Low/Intermediate-Resolution Testing

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 Typing, Low/Intermediate-Resolution Technical

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 Molecular Typing

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

CPT 81379: High-Resolution HLA Class I Typing

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

CPT 81380: High-Resolution HLA Class I Molecular Typing

Showing 1–10 of 13

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 81373: HLA Class I Low/Intermediate Resolution Molecular Test

Sign up for cpt 81373 policy alerts

Billing Code Overview

Catch payer policy changes before they impact reimbursement

Catch payer policy changes before they impact reimbursement

OpenPayer

CPT 81373: HLA Class I Low/Intermediate Resolution Molecular Test

Sign up for cpt 81373 policy alerts

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