D80.9
BillableImmunodeficiency with predominantly antibody defects, unspecified
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is D80.9 an HCC code?
Yes. D80.9 maps to Disorders of Immunity under the V24 model but is not retained in V28.
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 D80.9
For D80.9to 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 D80.9 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
D80.9 is the ICD-10-CM diagnosis code for immunodeficiency with predominantly antibody defects, unspecified. This code describes a condition where the immune system doesn't produce enough antibodies to fight infections, but the specific type of antibody deficiency is not specified. Patients with this condition are more susceptible to bacterial infections and may require immunoglobulin replacement therapy. D80.9 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 older CMS-HCC V24 model, D80.9 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.
Use this code only when the documentation indicates an antibody deficiency but does not specify the type (such as IgA, IgG, or IgM deficiency); if a specific antibody deficiency is documented, use the more specific code instead. Because D80.9 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 D80.9 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Use this code only when the documentation indicates an antibody deficiency but does not specify the type (such as IgA, IgG, or IgM deficiency); if a specific antibody deficiency is documented, use the more specific code instead
- •This is an unspecified code (ending in .9), so query the provider if more specific information about the type of antibody defect is available in the medical record to ensure accurate coding
Clinical Significance
Immunodeficiency with predominantly antibody defects, unspecified, indicates that a patient has been diagnosed with an antibody-mediated immunodeficiency but the specific type has not been determined or documented. These patients typically present with recurrent bacterial infections and may require immunoglobulin replacement therapy pending further immunological characterization.
Documentation Requirements
- ✓Documentation should include evidence supporting an antibody deficiency diagnosis (recurrent infections, low immunoglobulin levels), the reason why further specificity is unavailable, and the plan for additional workup to characterize the defect.
- ✓Include any immunoglobulin levels tested and vaccine challenge responses if performed.
- ✓Query the provider for more specific information when possible.
Commonly Confused Codes
- •D80.2 (selective Immunoglobulin A deficiency), D80.3 (selective Immunoglobulin G subclass deficiency), D80.4 (selective Immunoglobulin M deficiency), D83.9 (common variable immunodeficiency, unspecified, which requires CVID diagnostic criteria to be met), D84.9 (immunodeficiency, unspecified, an even broader code).