D71.8 ICD-10-CM Code: Other functional disorders of polymorphonuclear neutrophils

D71.8 is the ICD-10-CM diagnosis code for other functional disorders of polymorphonuclear neutrophils. A disorder where white blood cells are present in normal numbers but cannot function properly to fight infections. D71.8 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 other disorders of blood and blood-forming organs (d70-d77).

Under the CMS-HCC V28 risk adjustment model, D71.8 maps to Specified Immunodeficiencies and White Blood Cell Disorders (HCC 115) with a community, non-dual, aged base RAF weight of 0.565. D71.8 was not retained as a payment HCC under the older V24 model, so V28 introduced or recategorized it during the 2024–2026 phase-in. 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.

Document the specific functional defect of the neutrophils when available (e.g., chemotaxis, phagocytosis). Because D71.8 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.