D81.0
BillableSevere combined immunodeficiency [SCID] with reticular dysgenesis
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is D81.0 an HCC code?
Yes. D81.0 maps to Common Variable and Combined Immunodeficiencies 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 D81.0
For D81.0to 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 D81.0 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
D81.0 is the ICD-10-CM diagnosis code for severe combined immunodeficiency [scid] with reticular dysgenesis. A severe inherited immune disorder where the body cannot develop infection-fighting cells and has abnormal bone marrow development. D81.0 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, D81.0 maps to Common Variable and Combined Immunodeficiencies (HCC 114) with a community, non-dual, aged base RAF weight of 2.262. Under the older CMS-HCC V24 model, D81.0 maps to Disorders of Immunity (HCC 47) with a community, non-dual, aged base RAF weight of 0.665. 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 life-threatening condition requiring immediate documentation of reticular dysgenesis confirmation. Because D81.0 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 D81.0 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •This is a life-threatening condition requiring immediate documentation of reticular dysgenesis confirmation
- •Verify genetic testing results are documented to support diagnosis
Clinical Significance
Severe combined immunodeficiency with reticular dysgenesis is the most severe form of SCID, characterized by complete absence of both lymphoid and myeloid cell lineages due to a defect in mitochondrial adenylate kinase 2. This uniformly fatal condition without treatment presents in the neonatal period with profound pancytopenia, absent thymus, and extreme vulnerability to all types of infections.
Documentation Requirements
- ✓Documentation must include evidence of absent T-cells, B-cells, and natural killer cells, severe neutropenia/agranulocytosis confirming the myeloid defect, bone marrow biopsy showing reticular dysgenesis, genetic testing results when available, and treatment plan including hematopoietic stem cell transplantation.
- ✓Document the neonatal presentation and severity of clinical course.
Commonly Confused Codes
- •D81.1 (severe combined immunodeficiency with low T
- •and B-cell numbers, which preserves myeloid cells), D81.2 (severe combined immunodeficiency with low or normal B-cell numbers), D81.9 (combined immunodeficiency, unspecified, which lacks the reticular dysgenesis component), D70.0 (congenital agranulocytosis, which affects only neutrophils without the lymphoid deficiency).