ICD-10 Code D84.9 – Immunodeficiency, unspecified (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code D84.9 – Immunodeficiency, unspecified
What it is
D84.9 identifies a disorder in which the immune system is weakened, but the specific type of immunodeficiency is not documented. Use it when the record confirms immunodeficiency without naming a cause or subtype.
Clinical signs
Clinical features vary; refer to documentation. Commonly, records note recurrent or unusual infections, poor immune response, or a history suggesting impaired host defense, but you should not infer details that are not stated.
When to use this code
Use D84.9 when the clinician documents immunodeficiency, immune deficiency, or a weakened immune system and does not specify a more precise diagnosis. It is also appropriate when the chart lacks enough detail to assign a more specific code. Verify whether the cause is acquired, congenital, or medication-related before coding this unspecified option.
Do not use for
Do not use this code when the record identifies a specific immunodeficiency type, such as a defined hereditary or secondary condition. Also avoid it if the note only mentions infection risk or immunosuppression without documenting immunodeficiency. Check documentation.
Coding tip
Look for the exact wording in the assessment and problem list; if a more specific immunodeficiency is documented, code that instead of D84.9.