ICD-10 Code D46.21 – Refractory anemia with excess of blasts 1 (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code D46.21 – Refractory anemia with excess of blasts 1
What it is
D46.21 identifies refractory anemia with excess of blasts 1, a myelodysplastic syndrome in which the bone marrow makes abnormal blood cells and shows an increased number of blasts. Use it for the documented subtype, not for other marrow disorders.
Clinical signs
Patients often have signs of bone marrow failure such as anemia-related fatigue, easy bruising, or recurrent infections. Clinical features vary; refer to documentation, and confirm the reported blast percentage and subtype.
When to use this code
Use this code when the provider documents refractory anemia with excess of blasts 1, RAEB-1, or an equivalent myelodysplastic syndrome diagnosis. It also applies when the record clearly links the condition to the specific MDS subtype. If the note only says “myelodysplastic syndrome” without subtype, check documentation.
Do not use for
Do not use D46.21 for other myelodysplastic syndromes, nonspecific anemia, or acute leukemia. If the chart does not specify excess blasts 1, you should not assume this code.
Coding tip
Verify the exact MDS subtype in the pathology or provider note before assigning D46.21.