ICD-10 Code D81.89 – Other combined immunodeficiencies (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code D81.89 – Other combined immunodeficiencies
What it is
D81.89 identifies combined immune system disorders that affect both cellular and humoral immunity but do not fit a more specific ICD-10 category. Use it when the record describes a combined immunodeficiency without a named 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 immune pathway.
When to use this code
Use D81.89 when the clinician documents an “other” combined immunodeficiency and the chart does not identify a more specific diagnosis. It may also fit when the condition is confirmed but the exact genetic or syndromic type is not stated. Check documentation if the record only says “immunodeficiency” without combined involvement.
Do not use for
Do not use this code for isolated antibody deficiency, neutropenia, or other single-arm immune disorders. If a more specific combined immunodeficiency is documented, code that diagnosis instead.
Coding tip
Look for wording such as “combined immunodeficiency,” “T-cell and B-cell defect,” or “other specified immunodeficiency” before assigning D81.89.