D75.84
BillableOther platelet-activating anti-PF4 disorders
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is D75.84 an HCC code?
Yes. D75.84 maps to Von Willebrand Disease and Other Coagulation Defects under the CMS-HCC V28 risk adjustment model (and Coagulation Defects and Other Specified Hematological Disorders 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 D75.84
For D75.84 to 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 D75.84 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
D75.84 is the ICD-10-CM diagnosis code for other platelet-activating anti-pf4 disorders. This is a rare blood disorder where the immune system produces antibodies that attack platelets (blood cells that help with clotting) in response to a substance called PF4 (platelet factor 4). This condition can lead to abnormally low platelet counts and increased risk of blood clots. D75.84 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, D75.84 maps to Von Willebrand Disease and Other Coagulation Defects (HCC 112) with a community, non-dual, aged base RAF weight of 0.247. Under the older CMS-HCC V24 model, D75.84 maps to Coagulation Defects and Other Specified Hematological Disorders (HCC 48) with a community, non-dual, aged base RAF weight of 0.209. 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 code is typically used for heparin-induced thrombocytopenia (HIT) or similar immune-mediated platelet disorders; ensure clinical documentation clearly supports the anti-PF4 antibody diagnosis. Because D75.84 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 D75.84 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •This code is typically used for heparin-induced thrombocytopenia (HIT) or similar immune-mediated platelet disorders; ensure clinical documentation clearly supports the anti-PF4 antibody diagnosis
- •Verify that this is not a case of drug-induced thrombocytopenia that would require an additional external cause code (Chapter 20) to identify the triggering medication
Clinical Significance
Other platelet-activating anti-PF4 disorders encompass rare immune-mediated conditions where antibodies against platelet factor 4 activate platelets outside the context of heparin exposure. These disorders, including spontaneous heparin-induced thrombocytopenia and vaccine-induced immune thrombocytopenia and thrombosis, can cause severe thrombotic events and profound thrombocytopenia requiring urgent management.
Documentation Requirements
- ✓Documentation must establish the presence of anti-PF4 antibodies confirmed by laboratory testing (enzyme immunoassay or functional assay) and specify that the condition is not caused by heparin exposure.
- ✓Include platelet counts, thrombotic events if present, the triggering factor (vaccine, spontaneous), and the treatment plan including alternative anticoagulation strategies.
- ✓Document any associated thrombosis location and severity.
Use Additional Code
- code, if applicable, for adverse effect of other viral vaccine (T50.B95-)
Commonly Confused Codes
- •D75.821 (immune-mediated heparin-induced thrombocytopenia which requires heparin exposure as the trigger), D75.828 (other heparin-induced thrombocytopenia variants still linked to heparin), D68.69 (other thrombophilia not mediated by anti-PF4 antibodies), D69.59 (other secondary thrombocytopenia without the anti-PF4 mechanism).