D81: Combined immunodeficiencies

Codes under D81 (Combined immunodeficiencies). A ✓ marks a billable (fully specified) code; category codes without a ✓ are not billable on their own.

Code	Description	Billable
D81.0	Severe combined immunodeficiency [SCID] with reticular dysgenesis	✓
D81.1	Severe combined immunodeficiency [SCID] with low T- and B-cell numbers	✓
D81.2	Severe combined immunodeficiency [SCID] with low or normal B-cell numbers	✓
D81.3	Adenosine deaminase [ADA] deficiency	—
D81.4	Nezelof's syndrome	✓
D81.5	Purine nucleoside phosphorylase [PNP] deficiency	✓
D81.6	Major histocompatibility complex class I deficiency	✓
D81.7	Major histocompatibility complex class II deficiency	✓
D81.8	Other combined immunodeficiencies	—
D81.9	Combined immunodeficiency, unspecified	✓
D81.30	Adenosine deaminase deficiency, unspecified	✓
D81.31	Severe combined immunodeficiency due to adenosine deaminase deficiency	✓
D81.32	Adenosine deaminase 2 deficiency	✓
D81.39	Other adenosine deaminase deficiency	✓
D81.81	Biotin-dependent carboxylase deficiency	—
D81.82	Activated Phosphoinositide 3-kinase Delta Syndrome [APDS]	✓
D81.89	Other combined immunodeficiencies	✓
D81.810	Biotinidase deficiency	✓
D81.818	Other biotin-dependent carboxylase deficiency	✓
D81.819	Biotin-dependent carboxylase deficiency, unspecified	✓

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Informational only, not coding or medical advice. Verify against the official ICD-10-CM (FY2026) and your payer's guidelines.

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