Anemia ICD-10 Codes: 2026 Coding Guide

Anemia may look simple on a problem list, but coding it correctly often requires more than selecting the first diagnosis that appears in an electronic health record.

A patient may have iron deficiency anemia, acute blood loss anemia, anemia caused by chronic kidney disease, chemotherapy-induced anemia, or another condition entirely. Each diagnosis has different documentation and sequencing requirements. Choosing the wrong code can lead to medical necessity edits, delayed payment, undercoding, or claim denial.

This guide explains how to select the correct anemia ICD-10 code for 2026. It covers common code families, documentation requirements, sequencing rules, billing examples, audit risks, and practical steps for doctors, hospitals, clinics, coders, and medical billing teams.

Coding notice: This article provides general educational information. Always verify the code against the current ICD-10-CM Alphabetic Index, Tabular List, official guidelines, payer policy, and the documentation for the individual encounter.

What Is the ICD-10 Code for Anemia?

The general ICD-10-CM code for unspecified anemia is D64.9. However, D64.9 should be used only when the provider has documented anemia but has not identified a more specific type or cause.

Common alternatives include:

• D50.9: Iron deficiency anemia, unspecified
• D50.0: Iron deficiency anemia secondary to chronic blood loss
• D62: Acute posthemorrhagic anemia
• D63.0: Anemia in neoplastic disease
• D63.1: Anemia in chronic kidney disease
• D64.81: Anemia due to antineoplastic chemotherapy

The correct choice depends on the provider’s final diagnosis, the cause of the anemia, whether blood loss is acute or chronic, and whether another condition must be coded first.

Which ICD-10-CM Version Applies in 2026?

ICD-10-CM follows the federal fiscal year (October 1–September 30) rather than the calendar year. In 2026, healthcare providers should be aware that two ICD-10-CM code-set releases may apply due to the April 1 update.

• For services provided from April 1 through September 30, 2026, use the April 1, 2026, FY2026 ICD-10-CM release.
• For services provided on or after October 1, 2026, use the FY2027 ICD-10-CM code set.

Always select the code set based on the patient’s date of service or discharge date. Do not use a newly published code before its effective date.

Common Anemia ICD-10 Codes

The following table covers frequently reported anemia codes. It is a practical reference rather than a replacement for the complete ICD-10-CM Tabular List.

The FY2026 code set also includes detailed codes for hereditary hemolytic anemia, acquired hemolytic anemia, sickle-cell disorders, bone marrow failure syndromes, congenital anemia, and anemia of prematurity. These conditions should be coded to the documented subtype, complication, crisis status, trimester, or cause when the classification provides that detail.

How to Select the Correct Anemia ICD-10 Code

1. Start with the provider’s diagnosis

A coder should not diagnose anemia from laboratory values alone. Code assignment is based on the provider’s diagnostic statement that the condition exists.

For example, a low hemoglobin result does not automatically support D64.9, D62, or D50.9. The provider must document the condition and, when known, its type or cause.

The official guidelines state that code assignment is based on the provider’s diagnostic statement. If the record contains conflicting information, the provider should be queried.

2. Identify the type and cause

Look for documentation such as:

• Iron deficiency anemia
• Vitamin B12 deficiency anemia
• Folate deficiency anemia
• Acute blood loss anemia
• Chronic blood loss anemia
• Anemia due to CKD
• Anemia due to malignancy
• Chemotherapy-induced anemia
• Autoimmune hemolytic anemia
• Aplastic anemia
• Sideroblastic anemia
• Thalassemia
• Sickle-cell disease

When the cause is known, avoid reporting D64.9 simply because it is easier to find.

3. Determine whether blood loss is acute or chronic

This distinction changes the code.

Use D50.0 when the provider documents iron deficiency anemia caused by chronic blood loss. Common sources may include long-term gastrointestinal bleeding or prolonged heavy menstrual bleeding.

Use D62 when the provider documents acute posthemorrhagic or acute blood loss anemia, such as anemia following an acute hemorrhage, injury, operation, or sudden gastrointestinal bleed.

Do not assume acute blood loss anemia from a postoperative decline in hemoglobin. Normal postoperative blood loss, expected hemodilution, and clinically significant acute anemia are not automatically the same condition.

4. Check for an underlying disease

Codes in category D63 describe anemia as a manifestation of another disease.

When the documentation supports D63.0, D63.1, or D63.8, the underlying disease usually must also be reported. The Tabular List and official sequencing rules determine which condition appears first.

5. Review all instructional notes

After finding a possible code in the Alphabetic Index, verify it in the Tabular List.

Pay attention to:

• Code first
• Use additional code
• Code also
• Excludes1
• Excludes2
• Inclusion terms
• Required seventh characters
• Additional cause or adverse-effect codes

The FY2026 guidelines instruct coders to use both the Alphabetic Index and Tabular List and to report the highest supported level of specificity.

6. Sequence codes according to the encounter

The code representing the condition chiefly responsible for the encounter is not always the first code found in the chart.

Anemia related to cancer, chemotherapy, CKD, pregnancy, or a drug adverse effect may require multiple diagnoses in a specific order.

7. Check payer medical necessity requirements

An accurate diagnosis code does not automatically guarantee coverage.

The diagnosis must also support the medical necessity of the billed service under the patient’s benefit plan, national coverage determination, local coverage determination, or commercial payer policy. Requirements may differ for serum iron studies, vitamin assays, infusions, transfusions, erythropoiesis-stimulating agents, and other services.

Documentation Checklist for Anemia

Clear clinical documentation helps coders select a specific code and defend the claim during an audit.

Weak documentation

Low Hgb. Monitor CBC.

This statement does not clearly establish anemia or its cause.

Better documentation

Iron deficiency anemia due to chronic gastrointestinal blood loss. Continue oral iron and refer to gastroenterology for evaluation.

This note supports a more specific diagnosis and shows why further care is needed.

Strong CKD documentation

Anemia due to stage 4 chronic kidney disease. Hemoglobin remains below treatment goal. Continue ESA therapy and monitor CBC and iron indices.

This statement identifies both the anemia relationship and CKD stage.

High-Risk Anemia Sequencing Rules

Anemia in chronic kidney disease

Report D63.1 when the provider clearly links the anemia to chronic kidney disease.

The underlying CKD code from category N18 should be reported before D63.1. The CKD code should identify the documented stage.

Examples include:

• N18.31 for stage 3a CKD
• N18.32 for stage 3b CKD
• N18.4 for stage 4 CKD
• N18.5 for stage 5 CKD
• N18.6 for end-stage renal disease

A basic sequence is:

1. N18.- for the CKD stage
2. D63.1 for anemia in CKD

When hypertension and CKD coexist, category I12 or I13 may also apply, followed by an N18 code identifying the CKD stage. The exact order depends on the circumstances of the encounter and all applicable Tabular List instructions. CMS also expects dual diagnoses identifying both CKD-related anemia and CKD stage for relevant ESA claims.

Example

A patient receives treatment for anemia due to stage 4 CKD.

Possible coding:

• N18.4: Chronic kidney disease, stage 4
• D63.1: Anemia in chronic kidney disease

Do not report D63.1 without the underlying CKD diagnosis.

Anemia in neoplastic disease

Use D63.0 when the provider documents that the anemia is caused by the malignancy itself.

When an encounter is specifically for managing anemia associated with malignancy and only the anemia is treated, the official guideline still requires the malignancy to be sequenced first. D63.0 follows the cancer code.

Example

A patient with active colon cancer is admitted for a transfusion because of anemia caused by the cancer.

Sequence:

1. Appropriate active colon cancer code
2. D63.0: Anemia in neoplastic disease

This is an important exception. Many complications are sequenced before the malignancy when only the complication is treated, but malignancy-related anemia follows a different rule.

Anemia due to antineoplastic chemotherapy

Use D64.81 when the provider documents anemia as an adverse effect of correctly administered antineoplastic chemotherapy.

When the encounter is for treatment of chemotherapy-induced anemia:

1. D64.81 is sequenced first.
2. Report the appropriate malignancy code.
3. Report T45.1X5-, adverse effect of antineoplastic and immunosuppressive drugs, using the appropriate seventh character.

The required seventh character depends on whether the encounter represents active treatment, subsequent care, or a sequela. Do not automatically choose the initial-encounter character based only on whether this is the patient’s first visit to your organization.

Example

A patient with lung cancer presents for management of chemotherapy-induced anemia.

Possible sequence:

1. D64.81
2. Appropriate lung cancer code
3. T45.1X5A, when the encounter meets the definition of active treatment for the adverse effect

Anemia related to radiation therapy

When anemia is documented as an adverse effect of radiotherapy and the encounter is for managing the anemia:

1. Sequence the anemia code first.
2. Add the appropriate neoplasm code.
3. Add Y84.2 to identify radiotherapy as the cause of the abnormal reaction or later complication.

The provider should clearly distinguish anemia caused by the malignancy from anemia caused by treatment. The code and sequence are not the same.

Anemia complicating pregnancy

Anemia affecting pregnancy requires a code from category O99.01 in addition to the code identifying the specific anemia.

Available codes include:

• O99.011: Anemia complicating pregnancy, first trimester
• O99.012: Anemia complicating pregnancy, second trimester
• O99.013: Anemia complicating pregnancy, third trimester
• O99.019: Anemia complicating pregnancy, unspecified trimester
• O99.02: Anemia complicating childbirth
• O99.03: Anemia complicating the puerperium

The obstetric code is generally sequenced first, followed by the code identifying the anemia type. Chapter 15 codes receive sequencing priority unless the provider states that the pregnancy is incidental to the encounter.

Example

A pregnant patient in the second trimester has documented iron deficiency anemia.

Possible coding:

1. O99.012: Anemia complicating pregnancy, second trimester
2. D50.9: Iron deficiency anemia, unspecified

Use D50.0 instead of D50.9 when chronic blood loss is specifically documented.

Anemia Coding Examples

Can Anemia Be Coded From a Low Hemoglobin Result?

A low hemoglobin, hematocrit, red blood cell count, ferritin, or serum iron result does not by itself establish the type of anemia for coding.

The provider must interpret the findings and document their clinical significance. In the inpatient setting, abnormal diagnostic findings generally are not reported unless the provider identifies their significance. When the significance is unclear and the provider has ordered further evaluation or treatment, a query may be appropriate.

This distinction matters because the same laboratory pattern may be associated with several conditions, including:

• Iron deficiency
• Chronic inflammation
• Kidney disease
• Acute blood loss
• Hemolysis
• Bone marrow failure
• Nutritional deficiency
• Malignancy
• Medication effects

Coders should not infer the diagnosis or causal relationship.

Outpatient vs. Inpatient Anemia Coding

Outpatient encounters

Do not code diagnoses documented as:

• Probable
• Suspected
• Questionable
• Rule out
• Compatible with
• Consistent with
• Working diagnosis

Instead, code the condition to the highest degree of certainty known during the visit. That may include symptoms, a confirmed abnormal finding, or the reason for testing.

For example, when a physician documents “rule out iron deficiency anemia” during an office visit, D50.9 should not be reported unless the diagnosis is confirmed.

Inpatient admissions

For qualifying inpatient facilities, a diagnosis documented at discharge as probable, suspected, likely, possible, or still to be ruled out may generally be coded as though it existed.

This rule applies to inpatient admissions to short-term acute, long-term care, and psychiatric hospitals. It does not apply to physician office visits or hospital outpatient encounters.

Common Anemia Coding Mistakes

Using D64.9 when the type is documented

D64.9 is appropriate when the provider documents anemia without further detail. It is not the best choice when the note clearly states iron deficiency anemia, CKD-related anemia, acute blood loss anemia, or another specific diagnosis.

Coding iron deficiency from laboratory results

Low ferritin or iron may support the provider’s diagnosis, but the coder should not independently assign D50.9 without a diagnostic statement.

Confusing D50.0 with D62

Use D50.0 for iron deficiency anemia from chronic blood loss. Use D62 for acute posthemorrhagic anemia.

A patient can develop iron deficiency after continued blood loss, but the provider must establish the condition being treated at the current encounter.

Reporting D63.1 without CKD

D63.1 represents anemia in chronic kidney disease. The underlying CKD stage must also be coded.

Reporting D63.0 as the first-listed diagnosis

When anemia is due to malignancy, the malignancy is sequenced before D63.0, including an encounter where only the malignancy-associated anemia is treated.

Using D63.0 for chemotherapy-induced anemia

Anemia caused by the cancer is coded differently from anemia caused by chemotherapy.

• Cancer caused the anemia: D63.0
• Chemotherapy caused the anemia: D64.81

The provider should clearly identify the causal relationship.

Assuming every postoperative hemoglobin decline is anemia

A laboratory decline after surgery does not automatically establish acute blood loss anemia or a postprocedural complication.

Query the provider when the clinical significance is unclear.

Missing adverse-effect coding

When a properly administered drug causes anemia, the diagnosis may require both the anemia code and an adverse-effect code.

Coding an uncertain outpatient diagnosis

“Possible anemia” and “rule out anemia” should not be coded as confirmed during an outpatient visit.

Using an outdated code set

The code must be valid for the date of service. This becomes especially important around April 1 and October 1 updates.

Best Practices for Clean Anemia Claims

Build diagnosis-specific templates

Clinical templates should prompt providers to document:

• Anemia type
• Cause
• Acute or chronic status
• Disease relationship
• CKD stage
• Pregnancy trimester
• Current malignancy
• Drug or treatment relationship
• Blood-loss source

Templates should support documentation, not force a diagnosis that the provider has not clinically established.

Create targeted coding edits

Useful claim-scrubbing edits may include:

• Flag D63.1 when no N18 code is present
• Flag D63.0 when no active neoplasm code is present
• Flag D64.81 when no malignancy or adverse-effect code is present
• Review D64.9 when the note contains a more specific anemia diagnosis
• Check O99.01- codes for trimester accuracy
• Check diagnosis codes against the date-of-service code set

Review payer policies before treatment

Confirm coverage requirements for:

• Iron infusions
• Vitamin B12 injections
• Folate testing
• Ferritin and iron studies
• Blood transfusions
• ESA therapy
• Hematology testing
• Gastrointestinal evaluation for blood loss

A clinically correct diagnosis code can still be denied when the service falls outside a payer’s frequency, laboratory, drug, or coverage requirements.

Audit unspecified-code usage

A high rate of D64.9 may indicate:

• Incomplete documentation
• Missed coding specificity
• Poor provider-coder communication
• EHR default-code problems
• Weak clinical documentation improvement processes

Review a sample of D64.9 claims to determine whether a more specific diagnosis was available.

Query instead of assuming

A compliant query is appropriate when the record is:

• Conflicting
• Incomplete
• Clinically unclear
• Missing a causal relationship
• Missing acute-versus-chronic status
• Missing the clinical significance of abnormal findings

Queries should be non-leading and should include relevant clinical indicators and reasonable response options.

Frequently Asked Questions

1. What is the most common ICD-10 code for unspecified anemia?

D64.9 is the ICD-10-CM code for anemia, unspecified. Use it when the provider confirms anemia but does not document a more specific type or cause.

2. What is the ICD-10 code for iron deficiency anemia?

D50.9 is used for iron deficiency anemia when the cause is not specified. Use D50.0 when the provider documents iron deficiency anemia caused by chronic blood loss.

3. What is the ICD-10 code for acute blood loss anemia?

D62 is the code for acute posthemorrhagic anemia, commonly described as acute blood loss anemia.

4. What is the ICD-10 code for anemia in chronic kidney disease?

D63.1 represents anemia in chronic kidney disease. Report the underlying CKD stage from category N18 before D63.1.

5. Can D63.1 be billed by itself?

Generally, no. D63.1 describes anemia as a manifestation of CKD, so the underlying CKD diagnosis and stage should also be reported.

6. What is the difference between D63.0 and D64.81?

D63.0 is used when the malignancy causes the anemia. D64.81 is used when antineoplastic chemotherapy causes the anemia.

7. Can a coder diagnose anemia from a low hemoglobin level?

No. The provider must document the diagnosis and its clinical significance. A coder should not assign an anemia diagnosis solely from laboratory results.

8. How is anemia coded during pregnancy?

Report the appropriate O99.01- code based on trimester, childbirth, or puerperium, followed by a code identifying the specific anemia type.

9. Can “possible anemia” be coded during an office visit?

No. Outpatient uncertain diagnoses are not coded as confirmed. Code the symptoms, confirmed findings, or reason for the encounter instead.

10. Does the correct anemia diagnosis guarantee claim payment?

No. The code must be correct, supported by documentation, valid for the date of service, and consistent with the payer’s coverage and medical necessity requirements.

Conclusion

Accurate anemia coding begins with clear clinical documentation. The provider should identify the anemia type, underlying cause, acute or chronic status, and relationship to conditions such as CKD, malignancy, chemotherapy, blood loss, or pregnancy.

Avoid using D64.9 when a specific diagnosis is available. Review code-first notes, adverse-effect requirements, and sequencing instructions before submitting the claim. Most importantly, never assign an anemia diagnosis or causal relationship from laboratory values alone.

A focused review of unspecified anemia claims, CKD cases, oncology encounters, and postoperative records can uncover documentation gaps before they become denials or audit findings.