ICD-10 Code D81.8 – Other combined immunodeficiencies (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code D81.8 – Other combined immunodeficiencies
What it is
D81.8 identifies combined immunodeficiency conditions that do not fit a more specific ICD-10 category. Use it when documentation describes both humoral and cellular immune impairment, but the exact syndrome is not named.
Clinical signs
Clinical features vary; refer to documentation. Commonly reported findings include recurrent or severe infections, poor response to routine infections, and evidence of abnormal immune function affecting more than one immune pathway.
When to use this code
Use D81.8 when the provider documents an “other” combined immunodeficiency or a combined immune defect that is not otherwise classified. It is appropriate when the record supports immune deficiency involving both T-cell and B-cell function, but a more specific code is unavailable. Check documentation if the diagnosis is provisional or unspecified.
Do not use for
Do not use this code for isolated antibody deficiency, pure cellular immunodeficiency, or a more specific combined immunodeficiency with its own ICD-10 code. If the chart only says “immunodeficiency” without detail, check documentation.
Coding tip
Code D81.8 only when the record clearly supports a combined immunodeficiency and no more specific diagnosis is documented.