D59.9
BillableAcquired hemolytic anemia, unspecified
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is D59.9 an HCC code?
Yes. D59.9 maps to Hemolytic and Aplastic Anemias under the CMS-HCC V28 risk adjustment model (and Severe 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 D59.9
For D59.9 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 D59.9 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
D59.9 is the ICD-10-CM diagnosis code for acquired hemolytic anemia, unspecified. A condition where red blood cells are destroyed faster than the body can replace them, but the specific cause is not identified or documented. D59.9 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 hemolytic anemias (d55-d59).
Under the CMS-HCC V28 risk adjustment model, D59.9 maps to Hemolytic and Aplastic Anemias (HCC 109) with a community, non-dual, aged base RAF weight of 0.291. Under the older CMS-HCC V24 model, D59.9 maps to Severe Hematological Disorders (HCC 46) with a community, non-dual, aged base RAF weight of 0.666. 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 type of hemolytic anemia cannot be determined; review documentation for more specific hemolytic anemia codes (D59.0-D59.8). Because D59.9 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 D59.9 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
Clinical Significance
Acquired hemolytic anemia, unspecified is assigned when a patient has confirmed acquired hemolytic anemia but the documentation does not identify the specific type or cause. This code indicates a diagnostic workup gap, as the immune vs non-immune mechanism, causative agent, and underlying etiology remain undetermined. Providers should be queried to clarify the hemolysis mechanism (autoimmune vs mechanical vs drug-induced) and any identifiable triggers, as this information directly impacts treatment decisions.
Documentation Requirements
- ✓Document laboratory evidence confirming hemolytic anemia (elevated lactate dehydrogenase, elevated indirect bilirubin, low haptoglobin, reticulocytosis, peripheral smear findings).
- ✓Record hemoglobin values and transfusion history.
- ✓Include direct antiglobulin (Coombs) test results to distinguish immune from non-immune hemolysis.
- ✓Document what diagnostic workup has been performed and what is pending.
- ✓Submit a provider query requesting specification of the hemolysis type and cause.