D84.81 Immunodeficiency due to conditions classified elsewhere

Billable ICD-10-CM code, FY2026. Acts as a Complication or Comorbidity (CC) as a secondary diagnosis.

Excludes1 (never code together)

• certain disorders involving the immune mechanism (D80-D83, D84.0, D84.1, D84.9)
• human immunodeficiency virus [HIV] disease (B20)

Code first

• underlying condition, such as:
• chromosomal abnormalities (Q90-Q99)
• diabetes mellitus (E08-E13)
• malignant neoplasms (C00-C96)

Risk adjustment (HCC)

• CMS-HCC V22: HCC 47 — Disorders of Immunity
• RxHCC V08: HCC 99 — Immune Disorders
• ESRD V24: HCC 47

MS-DRG index

Defines the logic of DRG(s) 814-816 in MDC 16.

Medicare Code Edits (MCE v43.1 (April 2026))

• Manifestation codes as principal diagnosis: Manifestation codes describe the manifestation of an underlying disease, not the disease itself, and are not allowed as principal diagnosis.

Code annotations containing back-references to D84.81

Back-references to D84

• Type 1 Excludes: D72 Other disorders of white blood cells ("immunity disorders (D80-D89)")

Diagnosis Index entries for D84.81

• Immunodeficiency › due to › conditions classified elsewhere

Nearby codes

• D84 Other immunodeficiencies
• D84.0 Lymphocyte function antigen-1 [LFA-1] defect
• D84.1 Defects in the complement system
• D84.8 Other specified immunodeficiencies
• D84.81 Immunodeficiency due to conditions classified elsewhere (this code)
• D84.82 Immunodeficiency due to drugs and external causes
• D84.821 Immunodeficiency due to drugs
• D84.822 Immunodeficiency due to external causes
• D84.89 Other immunodeficiencies
• D84.9 Immunodeficiency, unspecified