D46.1
BillableRefractory anemia with ring sideroblasts
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is D46.1 an HCC code?
Yes. D46.1 maps to Myelodysplastic Syndromes, Multiple Myeloma, and Other Cancers 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 D46.1
For D46.1to 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 D46.1 during that encounter — not just copy-forwarded from a problem list.
What This Code Means
D46.1 is the ICD-10-CM diagnosis code for refractory anemia with ring sideroblasts. A bone marrow disorder where red blood cells cannot be produced normally and ring sideroblasts (abnormal iron-containing cells) are present in the bone marrow. D46.1 sits in the ICD-10-CM chapter for neoplasms (c00-d49), within the section covering neoplasms of uncertain behavior, polycythemia vera and myelodysplastic syndromes (d37-d48).
Under the CMS-HCC V28 risk adjustment model, D46.1 maps to Myelodysplastic Syndromes, Multiple Myeloma, and Other Cancers (HCC 19) with a community, non-dual, aged base RAF weight of 1.798. Under the older CMS-HCC V24 model, D46.1 maps to Severe Hematological Disorders (HCC 46) with a community, non-dual, aged base RAF weight of 1.372. 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.
Ring sideroblasts must be documented and confirmed on bone marrow examination. Because D46.1 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 D46.1 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •Ring sideroblasts must be documented and confirmed on bone marrow examination
- •This subtype has a different prognosis than D46.0, so accurate differentiation is important
Clinical Significance
Refractory anemia with ring sideroblasts is a myelodysplastic syndrome subtype characterized by iron-laden mitochondria forming a ring pattern around the nucleus of erythroblasts in the bone marrow. This subtype generally has a more favorable prognosis than other myelodysplastic syndromes, with lower risk of transformation to acute myeloid leukemia.
Documentation Requirements
- ✓Documentation must include bone marrow biopsy confirming ring sideroblasts (at least 15% of erythroblasts) with Prussian blue staining.
- ✓The blast percentage must be below 5%.
- ✓Document iron studies, cytogenetic analysis, and the SF3B1 mutation status if tested, as this mutation is found in most cases and is associated with better outcomes.
Commonly Confused Codes
- •D46.0 (refractory anemia without ring sideroblasts) lacks the ring sideroblast finding.
- •D46.B (refractory cytopenia with multilineage dysplasia and ring sideroblasts) indicates dysplasia in multiple cell lines.
- •D64.0 (hereditary sideroblastic anemia) is a congenital condition distinct from myelodysplastic syndrome.
- •D64.3 (other sideroblastic anemias) is used for acquired non-myelodysplastic forms.