D64.9: Anemia, unspecified

The ICD-10-CM code for anemia when the provider has documented the condition but the specific type is not established and not recorded.

Billable

FY2027

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At a glance

Code Family

D64: Other anemias

Condition

Anemia

Billable

Yes

HCC Mapping (v28)

No HCC mapping. D64.9 does not map to a CMS-HCC v28 category.

DRG Grouping

MS-DRG 811 or 812 (Red Blood Cell Disorders) as principal diagnosis under the FY2027 MS-DRG v44 grouper. As a secondary diagnosis D64.9 is not a CC or an MCC.

Effective Date

Valid in the FY2026 code set and unchanged in the FY2027 update.

Which D64 code do I assign?

Category D64 gathers the anemias that fall outside the nutritional, hemolytic and aplastic categories. It splits on the mechanism the record names, with D64.9 reserved for anemia whose type is neither documented nor determinable.

When documentation says…

Code

Anemia, type not determined

D64.9

Anemia, unspecified. The provider documents anemia. The record names no specific type and none can be determined from the chart.

Anemia due to antineoplastic chemotherapy

D64.81

Anemia due to antineoplastic chemotherapy. The record ties the anemia to the chemotherapy.

Sideroblastic anemia due to a drug or toxin

D64.2

Secondary sideroblastic anemia due to drugs and toxins. The note names the causative agent.

Iron deficiency anemia

D50.9

Iron deficiency anemia, unspecified. Iron deficiency is documented as the cause. D64.9 does not apply.

Anemia of chronic kidney disease

D63.1

Anemia in chronic kidney disease. Sequence the chronic kidney disease code from N18.- first. D64.9 does not apply.

Nutritional anemia NOS

D53.9

Nutritional anemia, unspecified. D53.9 carries an Excludes1 note for anemia NOS (D64.9). The two are not reported together for the same anemia.

Tabular notes

EXCLUDES1

Category D64 carries an Excludes1 note for refractory anemia (the D46 codes) and for refractory anemia with excess blasts in transformation [RAEB T] (the C92.0 codes). D53.9, nutritional anemia, unspecified, carries its own Excludes1 note for anemia NOS (D64.9). When nutritional anemia is the documented diagnosis, assign D53.9 rather than D64.9. An Excludes1 note means the two codes are not reported together for the same condition.

FY2027: EFFECTIVE 1 OCTOBER 2026

The FY2027 codes and tabular addenda make no addition, deletion or revision in category D64. D64.9 is unchanged in the FY2027 update.

Operational & financial impact

Why specificity matters beyond the chart: risk adjustment, DRG assignment and denial exposure all follow from which code is selected.

CMS-HCC v28 (PY2024+)

D64.9 does not map to any category in CMS-HCC v28. Unspecified anemia is not a risk adjustment bearing condition.

Certain specific anemia types carry HCC weight. Idiopathic aplastic anemia (D61.3), for example, maps to HCC 109. Aplastic anemia, unspecified (D61.9) maps to no v28 HCC.

MS-DRG v44 (FY2027)

MS-DRG 811: Red Blood Cell Disorders with MCC.

MS-DRG 812: Red Blood Cell Disorders without MCC.

A medical admission with D64.9 as the principal diagnosis groups to MS-DRG 811 or 812 under the FY2027 MS-DRG v44 grouper.

D64.9 is not a complication or comorbidity. It is not a major complication or comorbidity either. As a secondary diagnosis it does not move a case to a higher tier.

Specific anemia types such as aplastic anemia carry CC or MCC status. D61.9 is a CC and D61.3 is an MCC on the FY2027 lists.

Medicare and payer coverage

No National Coverage Determination governs anemia diagnosis coding in the outpatient setting.

WHERE SPECIFICITY IS LOST

Anemia documented as secondary to a chronic disease belongs in the D63.- codes. Sequence the underlying condition first. D64.9 does not apply in that circumstance.

Anemia documented as due to antineoplastic chemotherapy belongs in D64.81.

Iron deficiency, vitamin B12 deficiency and folate deficiency each have their own code family. Assigning D64.9 when the type is documented drops that detail from the record.

Documentation checklist to support D64.9

Chart elements that support code selection and reduce specificity-driven denials.

An explicit provider diagnosis of anemia in the encounter note.

Confirmation that the record names no specific anemia type and that none can be determined from the chart.

Laboratory results such as hemoglobin or hematocrit recorded as support. A laboratory value on its own does not carry the diagnosis.

A statement that the anemia type remains indeterminate at the time of the encounter.

For anemia secondary to a chronic disease, the underlying condition documented and sequenced first, with a code from the D63.- range in place of D64.9.

For anemia attributed to antineoplastic chemotherapy, the documented link to the chemotherapy, which directs the encounter to D64.81.

For outpatient encounters, a confirmed diagnosis only. Probable anemia is not coded in the outpatient setting.

For inpatient discharges, an attempt to record the most specific anemia type. D64.9 applies when the type remains unknown at discharge.

FAQ

Is D64.9 a billable code?

Yes. D64.9 is a billable ICD-10-CM code and is valid in the FY2027 code set from 1 October 2026. It is the residual code in category D64. Use it only when the anemia type is not determinable.

Can I assign D64.9 from a low hemoglobin alone?

No. Under the FY2027 ICD-10-CM guidelines, code assignment rests on provider documentation rather than on laboratory values. A hemoglobin or hematocrit result is not a diagnosis. The provider must document anemia for this code to apply.

Does D64.9 map to an HCC?

No. D64.9 does not map to any category in CMS-HCC v28. Unspecified anemia carries no risk adjustment weight. Some specific anemia types carry weight. Idiopathic aplastic anemia (D61.3), for example, maps to HCC 109.

My patient has anemia due to chronic kidney disease. Should I use D64.9?

No. When anemia is documented as secondary to chronic kidney disease, assign the chronic kidney disease code from N18.- first. Follow it with D63.1 for anemia in chronic kidney disease. D64.9 does not apply.

What is the difference between D64.9 and D53.9?

D53.9 is nutritional anemia, unspecified. It applies when the anemia is documented as nutritional in origin without further detail. D53.9 carries an Excludes1 note for anemia NOS (D64.9). The two are not reported together for the same anemia.

Does D64.9 affect the DRG?

As a secondary diagnosis, D64.9 does not affect the DRG. D64.9 is neither a complication or comorbidity nor a major complication or comorbidity under MS-DRG v44. As principal diagnosis it groups to MS-DRG 811 or 812, Red Blood Cell Disorders, in MDC 16. Specific anemia types such as aplastic anemia may carry CC or MCC status.

How does D64.9 differ between the outpatient and inpatient settings?

In the outpatient setting, assign D64.9 only when anemia is confirmed and the type is indeterminate. Probable anemia is not coded there. On the inpatient side, record the most specific anemia type at discharge. A probable type documented at discharge may be coded under UHDDS guidelines.

Did anything change for D64.9 in FY2027?

D64.9 is unchanged in the FY2027 update. The FY2027 update, effective 1 October 2026, makes no addition, deletion or revision in category D64.

Related codes

Codes in the same family as D64.9. Only codes with a published page render as links.

Sibling codes in the D64 family

D64.0: Hereditary sideroblastic anemia.
D64.1: Secondary sideroblastic anemia due to disease.
D64.2: Secondary sideroblastic anemia due to drugs and toxins.
D64.3: Other sideroblastic anemias.
D64.4: Congenital dyserythropoietic anemia.
D64.81: Anemia due to antineoplastic chemotherapy.
D64.89: Other specified anemias.

Additional codes to consider

Codes outside the D64 family considered alongside D64.9.

Consider instead

D50.9: Iron deficiency anemia, unspecified. Assign this code when iron deficiency is documented as the cause.
D51.9: Vitamin B12 deficiency anemia, unspecified.
D52.9: Folate deficiency anemia, unspecified.
D53.9: Nutritional anemia, unspecified. This code carries an Excludes1 note for anemia NOS (D64.9).
D57.00–D57.819: Sickle-cell disorders. Assign a code from category D57 when sickle cell disease is documented.
D61.9: Aplastic anemia, unspecified. This code is a CC and maps to no v28 HCC.
D63.0: Anemia in neoplastic disease. Code the neoplasm first.
D63.1: Anemia in chronic kidney disease. Code the chronic kidney disease first.

Sources

All claims on this page derive from government and professional-standards sources.

National Center for Health Statistics. (2026). International classification of diseases, tenth revision, clinical modification (ICD-10-CM) FY2027 files. https://www.cdc.gov/nchs/icd/icd-10-cm/files.html
Centers for Medicare & Medicaid Services and National Center for Health Statistics. (2026). ICD-10-CM official guidelines for coding and reporting FY2027. https://ftp.cdc.gov/pub/Health_Statistics/NCHS/Publications/ICD10CM/2027/ICD-10-CM-October-1-2026-FY27-Guidelines.pdf
Centers for Medicare & Medicaid Services. (2025). 2026 model software/ICD-10 mappings. https://www.cms.gov/medicare/payment/medicare-advantage-rates-statistics/risk-adjustment/2026-model-software-icd-10-mappings
Centers for Medicare & Medicaid Services. (2026). MS-DRG classifications and software, version 44. https://www.cms.gov/medicare/payment/prospective-payment-systems/acute-inpatient-pps/ms-drg-classifications-and-software