ICD-10-CM 2027
ICD-10 code for immunity deficiency
From the official ICD-10-CM alphabetic index entry “Deficiency, deficient › immunity”. Page updated September 29, 2026.
About coding immunity deficiency
The ICD-10-CM code for immunity deficiency is D84.9 (Immunodeficiency, unspecified). The official index lists 7 more specific codes, so check the documentation for details such as type, cause, site or severity before settling on D84.9.
Within D84, choose D84.9 (Immunodeficiency, unspecified) only when documentation doesn't support a more specific option: lymphocyte function antigen-1 [LFA-1] defect (D84.0), defects in the complement system (D84.1) and other specified immunodeficiencies (D84.8).
As a secondary diagnosis it is a CC (complication or comorbidity), which can move an inpatient stay into the "with CC" MS-DRG of its family, unless the principal diagnosis excludes it.
In MS-DRG v44.0, it is part of the grouping logic for DRG 814 (Reticuloendothelial and Immunity Disorders with MCC, relative weight 2.0729), DRG 815 (Reticuloendothelial and Immunity Disorders with CC, relative weight 1.0444) and DRG 816 (Reticuloendothelial and Immunity Disorders without CC/MCC, relative weight 0.7381), in MDC 16 (Diseases and Disorders of the Blood and Blood Forming Organs and Immunological Disorders), as a principal or secondary diagnosis. The DRG a claim lands in depends on the principal diagnosis, procedures and any CC/MCC secondary diagnoses.
More specific immunity deficiency codes (official index)
- cell-mediated D84.89 — Other immunodeficiencies
- with thrombocytopenia and eczema D82.0 — Wiskott-Aldrich syndrome
- combined D81.9 — Combined immunodeficiency, unspecified
- humoral D80.9 — Immunodeficiency with predominantly antibody defects, unspecified
- IgA (secretory) D80.2 — Selective deficiency of immunoglobulin A [IgA]
- IgG D80.3 — Selective deficiency of immunoglobulin G [IgG] subclasses
- IgM D80.4 — Selective deficiency of immunoglobulin M [IgM]
Common questions about immunity deficiency ICD-10 codes
What is the ICD-10 code for immunity deficiency?
- D84.9 — Immunodeficiency, unspecified. More specific codes apply when the documentation supports them: D84.89, D82.0, D81.9, D80.9 and others below.
What is the ICD-10 code for cell-mediated immunity deficiency?
- D84.89 — Other immunodeficiencies.
What is the ICD-10 code for combined immunity deficiency?
- D81.9 — Combined immunodeficiency, unspecified.
What is the ICD-10 code for humoral immunity deficiency?
- D80.9 — Immunodeficiency with predominantly antibody defects, unspecified.
What is the ICD-10 code for iga immunity deficiency?
- D80.2 — Selective deficiency of immunoglobulin A [IgA].
What is the ICD-10 code for igg immunity deficiency?
- D80.3 — Selective deficiency of immunoglobulin G [IgG] subclasses.
What is the ICD-10 code for igm immunity deficiency?
- D80.4 — Selective deficiency of immunoglobulin M [IgM].
Is D84.9 billable?
- Yes. D84.9 is a billable/specific ICD-10-CM code valid for FY2027 (October 1, 2026 – September 30, 2027).
Can D84.9 be used as a principal diagnosis?
- Yes. The Medicare Code Editor doesn't restrict D84.9 as a principal diagnosis.
Is D84.9 a CC or MCC?
- D84.9 is a CC (complication or comorbidity) under MS-DRG v44.0, unless excluded by the principal diagnosis.