ICD-10 Code D56.3 – Thalassemia minor (2026): Diagnosis, Symptoms & Billing Guide
2026 ICD-10-CM Diagnosis Code D56.3 – Thalassemia minor
What it is
D56.3 identifies thalassemia minor, also called thalassemia trait. It is a hereditary hemoglobin disorder that usually causes mild anemia or no symptoms, depending on the documented type.
Clinical signs
Clinical features vary; refer to documentation. Commonly noted findings include mild microcytic anemia, low mean corpuscular volume, and a family history of thalassemia or carrier status.
When to use this code
Use D56.3 when the provider documents thalassemia minor, trait, or carrier state as the diagnosis being addressed. It may also fit when evaluation confirms a hereditary thalassemia pattern with mild or absent symptoms.
Do not use it for nonspecific anemia without documentation of thalassemia. If the record only mentions suspected thalassemia, check documentation before coding.
Do not use for
Do not assign this code for thalassemia major, intermedia, or other specified thalassemia types. Also avoid it when the chart only supports iron deficiency anemia or an uncertain microcytic anemia.
Coding tip
Code the exact thalassemia type documented; if the note says trait or minor, D56.3 is the appropriate choice.