ICD-10 Code D81 – Combined immunodeficiencies (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code D81 – Combined immunodeficiencies
What it is
D81 identifies combined immunodeficiencies, a group of disorders affecting both cellular and humoral immune defenses. Use it when the record documents a combined immune system defect without a more specific subtype.
Clinical signs
Clinical features vary; refer to documentation. Commonly reported findings include recurrent or severe infections, poor response to routine infections, and evidence of impaired immune function affecting more than one arm of immunity.
When to use this code
Use D81 when the provider documents combined immunodeficiency, combined immune defect, or a related diagnosis and does not name a more specific code. It is appropriate for confirmed congenital or inherited immune deficiency descriptions. If the note gives a defined subtype, code that specific condition instead.
Do not use for
Do not use this code for isolated antibody deficiency, neutropenia, or other single-system immune disorders. Check documentation if the record only states “immunodeficiency” without clarifying that both cellular and humoral immunity are involved.
Coding tip
Look for the exact provider wording and code the most specific combined immunodeficiency documented.