D81.32
BillableAdenosine deaminase 2 deficiency
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is D81.32 an HCC code?
Yes. D81.32 maps to Severe Combined Immunodeficiency and Other Immune Disorders under the CMS-HCC V28 risk adjustment model (and Disorders of Immunity under V24).
HCC Category Mapping
RAF weights shown are the community, non-dual, aged base weights from the CMS risk adjustment model file. Actual per-patient RAF contribution depends on member segment, interactions, and the model year used by the payer. V28 is the CMS-HCC model phased in over payment years 2024–2026; V24 remains in use during the transition and for historical data.
MEAT Criteria for D81.32
For D81.32to count as a valid HCC diagnosis in a given encounter, the provider's documentation must show MEAT: Monitor, Evaluate, Assess, or Treat. A diagnosis from a prior year does not carry forward automatically — it has to be re-documented and supported each calendar year.
- MMonitor: signs, symptoms, disease progression, or lab trending documented in the note
- EEvaluate: test results, medication response, or physical findings reviewed by the provider
- AAssess: explicit mention in the assessment or plan with acknowledgment of status
- TTreat: medication, referral, procedure, therapy, or counseling tied to the diagnosis
Only one of M/E/A/T is required to support the code, but the documentation must be specific enough to show that the provider actually addressed D81.32 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
D81.32 is the ICD-10-CM diagnosis code for adenosine deaminase 2 deficiency. This is a rare genetic disorder where the body lacks an enzyme called adenosine deaminase 2, which normally helps break down certain substances in cells. This deficiency causes problems with the immune system and can lead to inflammation and infections. D81.32 sits in the ICD-10-CM chapter for diseases of the blood and blood-forming organs and certain disorders involving the immune mechanism (d50-d89), within the section covering certain disorders involving the immune mechanism (d80-d89).
Under the CMS-HCC V28 risk adjustment model, D81.32 maps to Severe Combined Immunodeficiency and Other Immune Disorders (HCC 114) with a community, non-dual, aged base RAF weight of 0.000. Under the older CMS-HCC V24 model, D81.32 maps to Disorders of Immunity (HCC 47) with a community, non-dual, aged base RAF weight of 0.472. V28 is the CMS-HCC risk adjustment model that reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition.
This is a specific subtype of adenosine deaminase deficiency - ensure you use D81.32 rather than the more general code D81.3 to capture the precise enzyme deficiency. Because D81.32 maps to a payment HCC, the provider's documentation must satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's Medicare Advantage risk adjustment score. When documentation is ambiguous, coders should issue a provider query rather than assume the highest-specificity variant.
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for D81.32 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •This is a specific subtype of adenosine deaminase deficiency - ensure you use D81.32 rather than the more general code D81.3 to capture the precise enzyme deficiency
- •This condition is often diagnosed in infancy or early childhood; verify documentation confirms ADA2 deficiency specifically and look for associated complications like recurrent infections or inflammatory manifestations that may require additional coding
Clinical Significance
Adenosine deaminase 2 deficiency is a distinct autoinflammatory and immunodysregulatory disorder caused by mutations in the CECR1/ADA2 gene. Unlike adenosine deaminase 1 deficiency, this condition primarily manifests with systemic vasculitis resembling polyarteritis nodosa, recurrent strokes, hepatosplenomegaly, and variable immunodeficiency including hypogammaglobulinemia and cytopenias rather than classic SCID.
Documentation Requirements
- ✓Documentation must include genetic testing confirming CECR1/ADA2 gene mutation, adenosine deaminase 2 enzyme activity levels, clinical manifestations including vasculitis, stroke history, liver and spleen assessment, immunoglobulin levels, complete blood count showing cytopenias, and treatment plan.
- ✓Document any history of lacunar strokes, livedo racemosa, or hepatosplenomegaly that are hallmark features.
Code Also
Commonly Confused Codes
- •D81.31 (severe combined immunodeficiency due to adenosine deaminase 1 deficiency, a completely different enzyme and clinical presentation), D81.30 (adenosine deaminase deficiency, unspecified), M30.0 (polyarteritis nodosa, which adenosine deaminase 2 deficiency can mimic), D81.39 (other adenosine deaminase deficiency for non-SCID adenosine deaminase 1 deficiency).