D80.4
BillableSelective deficiency of immunoglobulin M [IgM]
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is D80.4 an HCC code?
Yes. D80.4 maps to Disorders of Immunity, Neutropenia 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 D80.4
For D80.4to 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 D80.4 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
D80.4 is the ICD-10-CM diagnosis code for selective deficiency of immunoglobulin m [igm]. A condition where the body has abnormally low levels of IgM antibodies, an important early immune response protein. D80.4 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, D80.4 maps to Disorders of Immunity, Neutropenia (HCC 115) with a community, non-dual, aged base RAF weight of 0.369. Under the older CMS-HCC V24 model, D80.4 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.
IgM deficiency may increase susceptibility to certain infections, particularly encapsulated bacteria. Because D80.4 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 D80.4 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •IgM deficiency may increase susceptibility to certain infections, particularly encapsulated bacteria
- •Document any associated infections or clinical complications
Clinical Significance
Selective immunoglobulin M deficiency is a rare primary immunodeficiency characterized by isolated low Immunoglobulin M levels with normal Immunoglobulin G and Immunoglobulin A. Since Immunoglobulin M is the first antibody produced during an initial immune response, deficiency increases vulnerability to bloodstream infections with encapsulated organisms such as Streptococcus pneumoniae and Neisseria meningitidis.
Documentation Requirements
- ✓Documentation must include quantitative Immunoglobulin M levels demonstrating significant reduction below age-appropriate reference ranges, normal Immunoglobulin G and Immunoglobulin A levels to confirm selectivity, clinical manifestations including frequency and types of infections, and management plan.
- ✓Document any associated conditions such as autoimmune disease or malignancy that may cause secondary Immunoglobulin M deficiency.
Commonly Confused Codes
- •D80.5 (immunodeficiency with increased Immunoglobulin M, which is the opposite pattern with elevated Immunoglobulin M and low other classes), D80.2 (selective Immunoglobulin A deficiency, different immunoglobulin class), D80.3 (selective Immunoglobulin G subclass deficiency), D80.9 (unspecified antibody deficiency when the specific class is not documented).