ICD-10-CM 2027
ICD-10 code for immunodeficiency
From the official ICD-10-CM alphabetic index entry “Immunodeficiency”. Page updated September 29, 2026.
About coding immunodeficiency
The ICD-10-CM code for immunodeficiency is D84.9 (Immunodeficiency, unspecified). The official index lists 40 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 immunodeficiency codes (official index)
- with
- adenosine-deaminase deficiency D81.30 — Adenosine deaminase deficiency, unspecified
- antibody defects D80.9 — Immunodeficiency with predominantly antibody defects, unspecified
- specified type NEC D80.8 — Other immunodeficiencies with predominantly antibody defects
- hyperimmunoglobulinemia D80.6 — Antibody deficiency with near-normal immunoglobulins or with hyperimmunoglobulinemia
- increased immunoglobulin M (IgM) D80.5 — Immunodeficiency with increased immunoglobulin M [IgM]
- major defect D82.9 — Immunodeficiency associated with major defect, unspecified
- specified type NEC D82.8 — Immunodeficiency associated with other specified major defects
- partial albinism D82.8 — Immunodeficiency associated with other specified major defects
- short-limbed stature D82.2 — Immunodeficiency with short-limbed stature
- thrombocytopenia and eczema D82.0 — Wiskott-Aldrich syndrome
- antibody with
- hyperimmunoglobulinemia D80.6 — Antibody deficiency with near-normal immunoglobulins or with hyperimmunoglobulinemia
- near-normal immunoglobulins D80.6 — Antibody deficiency with near-normal immunoglobulins or with hyperimmunoglobulinemia
- autosomal recessive, Swiss type D80.0 — Hereditary hypogammaglobulinemia
- combined D81.9 — Combined immunodeficiency, unspecified
- biotin-dependent carboxylase D81.819 — Biotin-dependent carboxylase deficiency, unspecified
- biotinidase D81.810 — Biotinidase deficiency
- holocarboxylase synthetase D81.818 — Other biotin-dependent carboxylase deficiency
- specified type NEC D81.818 — Other biotin-dependent carboxylase deficiency
- severe (SCID) D81.9 — Combined immunodeficiency, unspecified
- with
- low or normal B-cell numbers D81.2 — Severe combined immunodeficiency [SCID] with low or normal B-cell numbers
- low T- and B-cell numbers D81.1 — Severe combined immunodeficiency [SCID] with low T- and B-cell numbers
- reticular dysgenesis D81.0 — Severe combined immunodeficiency [SCID] with reticular dysgenesis
- specified type NEC D81.89 — Other combined immunodeficiencies
- common variable D83.9 — Common variable immunodeficiency, unspecified
- with
- abnormalities of B-cell numbers and function D83.0 — Common variable immunodeficiency with predominant abnormalities of B-cell numbers and function
- autoantibodies to B- or T-cells D83.2 — Common variable immunodeficiency with autoantibodies to B- or T-cells
- immunoregulatory T-cell disorders D83.1 — Common variable immunodeficiency with predominant immunoregulatory T-cell disorders
- specified type NEC D83.8 — Other common variable immunodeficiencies
- due to
- conditions classified elsewhere D84.81 — Immunodeficiency due to conditions classified elsewhere
- drugs D84.821 — Immunodeficiency due to drugs
- external causes D84.822 — Immunodeficiency due to external causes
- medication (current or past) D84.821 — Immunodeficiency due to drugs
- following hereditary defective response to Epstein-Barr virus (EBV) D82.3 — Immunodeficiency following hereditary defective response to Epstein-Barr virus
- selective, immunoglobulin
- A (IgA) D80.2 — Selective deficiency of immunoglobulin A [IgA]
- G (IgG) (subclasses) D80.3 — Selective deficiency of immunoglobulin G [IgG] subclasses
- M (IgM) D80.4 — Selective deficiency of immunoglobulin M [IgM]
- severe combined (SCID) D81.9 — Combined immunodeficiency, unspecified
- due to adenosine deaminase deficiency D81.31 — Severe combined immunodeficiency due to adenosine deaminase deficiency
- specified type NEC D84.89 — Other immunodeficiencies
- X-linked, with increased IgM D80.5 — Immunodeficiency with increased immunoglobulin M [IgM]
Common questions about immunodeficiency ICD-10 codes
What is the ICD-10 code for immunodeficiency?
- D84.9 — Immunodeficiency, unspecified. More specific codes apply when the documentation supports them: D81.30, D80.9, D80.8, D80.6 and others below.
What is the ICD-10 code for combined immunodeficiency?
- D81.9 — Combined immunodeficiency, unspecified.
What is the ICD-10 code for common variable immunodeficiency?
- D83.9 — Common variable immunodeficiency, unspecified.
What is the ICD-10 code for severe combined immunodeficiency?
- D81.9 — Combined immunodeficiency, unspecified.
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.