What is ICD-10 code D56.0?

D56.0 is the ICD-10-CM diagnosis code for Alpha thalassemia. Alpha thalassemia is an inherited blood disorder where the body doesn't make enough alpha-globin protein, a component of hemoglobin that carries oxygen in red blood cells. This results in anemia, fatigue, and potentially serious complications if severe. D56.0 is a billable code, meaning it can be reported on a claim as a primary or secondary diagnosis when supported by documentation. D56.0 is part of the FY2026 ICD-10-CM code set published by the CMS National Center for Health Statistics and used on Medicare, Medicaid, and commercial claims in the United States.

Yes. D56.0 is a billable ICD-10-CM code that can be reported on professional and institutional claims as a primary or secondary diagnosis when the provider documentation supports the specific condition described. Billable codes in ICD-10-CM are coded to the highest level of specificity available for the documented diagnosis. D56.0 is current for fiscal year 2026 and remains in the active CMS ICD-10-CM code set published by the National Center for Health Statistics.

What is the V28 vs V24 difference for D56.0?

CMS phased in the V28 risk adjustment model over payment years 2024 (33%), 2025 (67%), and 2026 (100%), replacing V24. V28 consolidates HCC categories, removes some lower-acuity conditions, and recalibrates RAF weights across the entire model. D56.0 was a payment HCC under V24 (Coagulation Defects and Other Specified Hematological Disorders) but the V28 recalibration removed it from the risk adjustment model. Both models can still appear in legacy data and in payer-specific lookback periods.

What should coders know when reporting D56.0?

Verify the specific type of alpha thalassemia (such as alpha thalassemia trait, HbH disease, or hydrops fetalis) in the clinical documentation, as these may require additional specificity codes Check for associated complications like splenomegaly, bone deformities, or transfusion dependency that should be coded separately to capture the full clinical picture Because D56.0 maps to a payment HCC, the documentation must also satisfy MEAT criteria (Monitor, Evaluate, Assess, or Treat) for the encounter to count toward the patient's risk adjustment score.

D56.0: Alpha thalassemia — ICD-10 | Coagulation Defects and Other Specified Hematological

ICD-10-CM Code View

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Code lookupD56.0Effective periodFY2026 Apr Update (Apr 1-Sep 30)

FY 2026 Apr update / Diseases of the blood and blood-forming organs and certain disorders involving the immune mechanism (D50-D89) / Hemolytic anemias (D55-D59)

D56.0

Billable / SpecificICD-10-CMOfficial ICD-10-CMCodebook guidance

Alpha thalassemia

Alpha thalassemia is an inherited blood disorder where the body doesn't make enough alpha-globin protein, a component of hemoglobin that carries oxygen in red blood cells. This results in anemia, fatigue, and potentially serious complications if severe.

Buddy Insight

Alpha thalassemia encompasses a spectrum of inherited hemoglobin disorders caused by deletion or mutation of one to four alpha-globin genes.

CMS-HCC V28

Not risk-adjusted for this model/period.

RAF 0

CMS-HCC V24

Mapped

HCC 48

Coagulation Defects and Other...

RAF 0.209

ACA/HHS

Not risk-adjusted for this model/period.

RAF 0

ESRD/PACE

Mapped

HCC 48

Coagulation Defects and Other...

RAF 0.0

RXHCC

Not risk-adjusted for this model/period.

RAF 0

Code Trumping

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Code Book Path

Official

D56Thalassemia

D56.0Alpha thalassemia

Inclusion Terms

Official

Alpha thalassemia major
Hemoglobin H Constant Spring
Hemoglobin H disease
Hydrops fetalis due to alpha thalassemia
Severe alpha thalassemia

Excludes 2

Official

ICD-10-CM does not list Excludes 2 notes for D56.0 in this effective period.

Related Child Codes

Official

D56.1Beta thalassemia

D56.2Delta-beta thalassemia

D56.3Thalassemia minor

D56.4Hereditary persistence of fetal hemoglobin [HPFH]

D56.5Hemoglobin E-beta thalassemia

Includes

Official

ICD-10-CM does not list Includes notes for D56.0 in this effective period.

Excludes 1

Official

alpha thalassemia trait or minor (D56.3)
asymptomatic alpha thalassemia (D56.3)
hydrops fetalis due to isoimmunization (P56.0)
hydrops fetalis not due to immune hemolysis (P83.2)

Code First

Official

ICD-10-CM does not list Code First sequencing instructions for D56.0 in this effective period.

Use Additional

Official

code, if applicable, for hydrops fetalis due to alpha thalassemia (P56.99)

Code Also

Official

ICD-10-CM does not list Code Also instructions for D56.0 in this effective period.

Buddy Documentation Tip

HCC Buddy guidance

Documentation must specify the type and severity of alpha thalassemia (silent carrier, trait, Hemoglobin H disease, or hydrops fetalis) with supporting genetic testing or hemoglobin electrophoresis results.

Record baseline hemoglobin and mean corpuscular volume, transfusion requirements, iron studies to differentiate from iron deficiency, and any complications such as splenomegaly or bone deformities.

Genetic counseling status should be noted.

MEAT Support

HCC Buddy guidance

Record baseline hemoglobin and mean corpuscular volume, transfusion requirements, iron studies to differentiate from iron deficiency, and any complications such as splenomegaly or bone deformities.

Genetic counseling status should be noted.

Audit Caution

HCC Buddy guidance

This code has no V28 HCC mapping and will lose risk adjustment value in the model transition. Alpha thalassemia trait (two-gene deletion) is often an incidental finding and may not require active management, but should still be documented as a chronic condition. Do not confuse with iron deficiency anemia -

iron studies will be normal or elevated in thalassemia. Ensure the provider documents alpha thalassemia specifically, not just 'thalassemia trait.'

Common Mistakes

HCC Buddy guidance

D56.0 vs. D56.1 (Beta thalassemia) -

different globin chain affected with distinct genetic basis and clinical features. D56.0 vs. D50.9 (Iron deficiency anemia, unspecified) -

alpha thalassemia trait is commonly misdiagnosed as iron deficiency due to microcytosis. D56.0 vs. D56.3 (Thalassemia minor) -

D56.3 is for thalassemia minor not otherwise specified, while D56.0 is specifically alpha thalassemia.

Last updated: FY2026 ICD-10-CM Apr update, Apr 1, 2026 through Sep 30, 2026. CMS-HCC V28 is 100% phased in for payment year 2026.

Is D56.0 an HCC code?

Yes. D56.0 maps to Coagulation Defects and Other Specified Hematological Disorders under the V24 model but is not retained in V28.

HCC Category Mapping

V24HCC 48, Coagulation Defects and Other Specified Hematological Disorders

0.209

ESRDHCC 48, Coagulation Defects and Other Specified Hematological Disorders

0.000

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 D56.0

For D56.0to 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 D56.0 during that encounter, not just copy-forwarded from a problem list.

Coder workflow notes

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What This Code Means

D56.0 is the ICD-10-CM diagnosis code for alpha thalassemia. Alpha thalassemia is an inherited blood disorder where the body doesn't make enough alpha-globin protein, a component of hemoglobin that carries oxygen in red blood cells. This results in anemia, fatigue, and potentially serious complications if severe. D56.0 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 older CMS-HCC V24 model, D56.0 maps to Coagulation Defects and Other Specified Hematological Disorders (HCC 48) with a community, non-dual, aged base RAF weight of 0.209. 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.

Verify the specific type of alpha thalassemia (such as alpha thalassemia trait, HbH disease, or hydrops fetalis) in the clinical documentation, as these may require additional specificity codes. Because D56.0 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 D56.0 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.

Coding Tips

•Verify the specific type of alpha thalassemia (such as alpha thalassemia trait, HbH disease, or hydrops fetalis) in the clinical documentation, as these may require additional specificity codes
•Check for associated complications like splenomegaly, bone deformities, or transfusion dependency that should be coded separately to capture the full clinical picture

Clinical Significance

Alpha thalassemia encompasses a spectrum of inherited hemoglobin disorders caused by deletion or mutation of one to four alpha-globin genes. Clinical severity ranges from the silent carrier state (one gene affected) and alpha thalassemia trait (two genes) to Hemoglobin H disease (three genes) and the fatal hydrops fetalis (four genes). This is particularly prevalent in Southeast Asian, African, and Mediterranean populations, and proper classification impacts genetic counseling and clinical management.

Documentation Requirements

✓Documentation must specify the type and severity of alpha thalassemia (silent carrier, trait, Hemoglobin H disease, or hydrops fetalis) with supporting genetic testing or hemoglobin electrophoresis results.
✓Record baseline hemoglobin and mean corpuscular volume, transfusion requirements, iron studies to differentiate from iron deficiency, and any complications such as splenomegaly or bone deformities.
✓Genetic counseling status should be noted.

Excludes 1, Do NOT code together

alpha thalassemia trait or minor (D56.3)
asymptomatic alpha thalassemia (D56.3)
hydrops fetalis due to isoimmunization (P56.0)
hydrops fetalis not due to immune hemolysis (P83.2)

Use Additional Code

code, if applicable, for hydrops fetalis due to alpha thalassemia (P56.99)

Commonly Confused Codes

•D56.0 vs. D56.1 (Beta thalassemia) -
•different globin chain affected with distinct genetic basis and clinical features. D56.0 vs. D50.9 (Iron deficiency anemia, unspecified) -
•alpha thalassemia trait is commonly misdiagnosed as iron deficiency due to microcytosis. D56.0 vs. D56.3 (Thalassemia minor) -
•D56.3 is for thalassemia minor not otherwise specified, while D56.0 is specifically alpha thalassemia.