Z21 Asymptomatic human immunodeficiency virus [HIV] infection status

The ICD-10-CM code for Asymptomatic human immunodeficiency virus [HIV] infection status is Z21 (FY2026). It is a billable, claim-ready diagnosis code.

Classification

Chapter

21: Factors influencing health status and contact with health services (Z00-Z99)

Section

Z20-Z29: Persons with potential health hazards related to communicable diseases (Z20-Z29)

Category Z21

1 code (1 billable)

FY2026 Status

Stable since FY2024

Also Known As

ICD-10-CM Alphabetic Index entries that lead to Z21:

• Syndrome › seroconversion, retroviral (acute)
• Status (post) › human immunodeficiency virus (HIV) infection, asymptomatic
• HIV › positive, seropositive
• Syndrome › retroviral seroconversion (acute)
• Test, tests, testing (for) › HIV (human immunodeficiency virus) › seropositive
• Human › immunodeficiency virus (HIV) disease (infection) › asymptomatic status
• Test, tests, testing (for) › HIV (human immunodeficiency virus) › positive

Inclusion Terms

• HIV positive NOS

U.S. Hospital Utilization

• An estimated 113,165 U.S. inpatient stays in 2023 included Z21 among the documented diagnoses.

Source: National Inpatient Sample (NIS), Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality, 2016–2023. National survey-weighted estimates.

Prevalence & Statistics

• An estimated 1.2 million people in the United States were living with diagnosed and undiagnosed HIV at the end of 2022. (CDC National Center for HIV, Viral Hepatitis, STD, and TB Prevention (NCHHSTP) — HIV Surveillance Supplemental Report, 2024, 2022)

Official Coding Guidelines

Asymptomatic HIV infection status: assign Z21

When “HIV positive,” “HIV test positive,” or similar terminology is documented, and there is no documentation of symptoms or HIV-related illness, code Z21, Asymptomatic human immunodeficiency virus [HIV] infection status, should be assigned.

Previously diagnosed HIV-related illness (assign B20)

(g) Previously diagnosed HIV-related illness Patients with documentation of a prior diagnosis of an HIV-related illness should be coded to B20. Once an HIV-related illness has developed, code B20 should always be assigned on every subsequent admission/encounter. Patients previously diagnosed with any HIV illness (B20) should never be assigned to R75, Inconclusive laboratory evidence of human immunodeficiency virus [HIV] or Z21, Asymptomatic human immunodeficiency virus [HIV] infection status.

Source: CMS — ICD-10-CM Official Guidelines for Coding and Reporting, FY2026

References

• CMS — ICD-10-CM Official Code Set and Guidelines, FY2026
• CDC/NCHS — ICD-10-CM Files and Browser Tool
• AHRQ — HCUP National Inpatient Sample, Frequencies by Diagnosis Code (2016–2023)
• CDC National Center for HIV, Viral Hepatitis, STD, and TB Prevention (NCHHSTP) — HIV Surveillance Supplemental Report, 2024 (2022)