ICD-10 Code D81.3 – Adenosine deaminase [ADA] deficiency (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code D81.3 – Adenosine deaminase [ADA] deficiency
What it is
D81.3 identifies adenosine deaminase deficiency, a rare inherited immunodeficiency that impairs normal immune cell development. It is a cause of severe combined immunodeficiency and affects both cellular and humoral immunity.
Clinical signs
Clinical features vary; refer to documentation. Typical findings include recurrent severe infections, chronic diarrhea, failure to thrive, and markedly reduced immune function in infancy or early childhood.
When to use this code
Use D81.3 when the provider documents ADA deficiency, adenosine deaminase deficiency, or ADA-related severe combined immunodeficiency. Code it for confirmed diagnoses, genetic or immunology workups that establish the condition, and problem list entries tied to the disorder.
Do not use it for general immune weakness without a specific diagnosis. Check documentation if the record only mentions suspected SCID, abnormal screening, or family history.
Do not use for
Do not use this code for other combined immunodeficiencies, nonspecific hypogammaglobulinemia, or isolated laboratory abnormalities. If the record does not clearly identify ADA deficiency, check documentation.
Coding tip
Assign D81.3 only when ADA deficiency is explicitly documented or clearly confirmed in the chart.