ICD-10 Code D81.1 – Severe combined immunodeficiency [SCID] with low T- and B-cell numbers (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code D81.1 – Severe combined immunodeficiency [SCID] with low T- and B-cell numbers
What it is
D81.1 identifies severe combined immunodeficiency with low T- and B-cell numbers. It describes a profound inherited immune disorder affecting both cellular and humoral immunity.
Clinical signs
Clinical features vary; refer to documentation. Typical findings include recurrent or severe infections, poor growth, chronic diarrhea, and marked lymphopenia with reduced T and B lymphocytes.
When to use this code
Use D81.1 when the provider documents SCID specifically with low T- and B-cell numbers. It also applies when the diagnosis is confirmed by immunologic testing or genetic workup and recorded in the chart. Do not code it from suspicion alone.
Do not use for
Do not use this code for nonspecific immunodeficiency, isolated antibody deficiency, or SCID without documentation of low T- and B-cell numbers. Check documentation if the subtype is unclear.
Coding tip
Verify the exact SCID subtype in the assessment or problem list before assigning D81.1.