ICD-10 Code D84.81 – Immunodeficiency due to conditions classified elsewhere (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code D84.81 – Immunodeficiency due to conditions classified elsewhere
What it is
D84.81 identifies an immune deficiency that occurs because of another documented condition. You use it when the weakened immune state is secondary, not a primary immunodeficiency disorder.
Clinical signs
Clinical features vary; refer to documentation. Commonly, the record describes recurrent, unusual, or persistent infections in the setting of an underlying disease that affects immune function.
When to use this code
Use this code when the provider documents immunodeficiency caused by another condition, such as a chronic illness or disorder classified elsewhere. It should support the underlying diagnosis, not replace it. Code the causal condition first when directed by the record and coding guidelines.
Do not use for
Do not use D84.81 for primary or inherited immunodeficiency disorders. Also avoid it when the chart does not clearly link the immune deficiency to another documented condition; check documentation.
Coding tip
Look for explicit wording such as “secondary immunodeficiency” or “immunodeficiency due to” before assigning D84.81.