2026 ICD-10-CM Diagnosis Code D46.21Refractory anemia with excess of blasts 1
ICD-10-CM Codes›C00–D49›D37-D48›D46
- Billable — Valid for Submission
- Risk Adjusts — HCC 19
- Not Chronic
D46.21 is a billable ICD-10-CM diagnosis code for refractory anemia with excess of blasts 1. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 811 through 812. Coders also document this condition as myelodysplastic syndrome with excess blasts. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Myelodysplastic syndrome (MDS).
For Medicare Advantage risk adjustment, D46.21 maps to CMS-HCC Category 19 (Myelodysplastic Syndromes, Multiple Myeloma, and Other Cancers) under the V28 model, adding a risk factor of about 1.798 for a community, non-dual, aged beneficiary in payment year 2026.
Code Identity
Code Classification
Medicare Risk Adjustment (HCC)Billing
D46.21 maps to a payment category in the CMS-HCC model used to risk-adjust Medicare Advantage payments. Weights are the published community factors for payment year 2026.
Source: CMS Payment Year 2026 risk adjustment mappings and model software. Weights are relative factors, not dollar amounts; a beneficiary's total RAF also includes demographics and interactions. Browse all CMS-HCC categories.
Approximate SynonymsGuidance
Alternate terms and clinical phrases that map to this code.
- Myelodysplastic syndrome with excess blasts
- Myelodysplastic syndrome with excess blasts-1
Tabular List NotesGuidance
Coding notes and annotation back-references applicable to this code.
Inclusion Terms
- RAEB 1
These terms are the conditions for which that code is to be used. The terms may be synonyms of the code title, or, in the case of "other specified" codes, the terms are a list of the various conditions assigned to that code. The inclusion terms are not necessarily exhaustive. Additional terms found only in the Alphabetic Index may also be assigned to a code.
Index to Diseases and InjuriesGuidance
Alphabetical index entries that point to this code.
Clinical ClassificationClinical
AHRQ’s CCSR groups this code into broader clinical categories.
Patient EducationClinical
Myelodysplastic Syndromes
Your bone marrow is the spongy tissue inside some of your bones, such as your hip and thigh bones. It contains immature cells, called stem cells. The stem cells can develop into the red blood cells that carry oxygen through your body, the white blood cells that fight infections, and the platelets that help with blood clotting.
Read the full article at MedlinePlus
Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.
Convert D46.21 to ICD-9-CMHistory
The closest ICD-9-CM equivalents under the General Equivalence Mappings.
Code HistoryHistory
Questions About D46.21Overview
What is the ICD-10 code for refractory anemia with excess of blasts 1?
The ICD-10-CM code for refractory anemia with excess of blasts 1 is D46.21 (sometimes written as D4621). It is billable on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
Is D46.21 (Refractory anemia with excess of blasts [RAEB]) a billable code?
Yes. This is a billable ICD-10-CM code, specific enough to report refractory anemia with excess of blasts 1 on HIPAA-covered claims from October 1, 2025 through September 30, 2026.
What MS-DRG does D46.21 group to?
When refractory anemia with excess of blasts 1 is the principal diagnosis on an inpatient stay, it groups to MS-DRG 811, 812, with relative weights from 0.9182 to 1.4043 depending on complications. Higher weights mean higher Medicare reimbursement.
What is the ICD-9 equivalent of D46.21?
Under the General Equivalence Mappings, refractory anemia with excess of blasts 1 converts to ICD-9-CM 238.72 (low grde myelody syn les). The mapping is approximate, so confirm the match fits the documentation.
What HCC is D46.21?
D46.21 (refractory anemia with excess of blasts 1) maps to CMS-HCC Category 19 (Myelodysplastic Syndromes, Multiple Myeloma, and Other Cancers), commonly written as HCC 19, in the CMS-HCC V28 model used for Medicare Advantage risk adjustment in payment year 2026. It mapped to HCC 46 under the retired V24 model. It also maps in the PACE (CMS-HCC V22), ESRD (V21), and ESRD (V24) models. In the Part D prescription drug model it maps to RxHCC 19.
Does D46.21 risk-adjust for Medicare Advantage payment?
Yes. When documented and reported on a Medicare Advantage encounter, D46.21 adds a risk adjustment factor of about 1.798 to the beneficiary's RAF score for a community, non-dual, aged enrollee (published V28 weights range from 0.957 to 1.989 depending on the payment segment). A more severe related category (HCC 17 and HCC 18) supersedes it when both are reported. See the full factor table on the HCC 19 category page.
