2026 ICD-10-CM Diagnosis Code D51.1Vitamin B12 deficiency anemia due to selective vitamin B12 malabsorption with proteinuria

ICD-10-CM Codes›D50–D89›D50-D53›D51

ICD-10-CM D51.1
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

D51.1 is a billable ICD-10-CM diagnosis code for vitamin B12 deficiency anemia due to selective vitamin B12 malabsorption with proteinuria. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 811 through 812. Coders also document this condition as familial megaloblastic anemia. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Nutritional anemia.

Code Identity

ICD-10-CM Code
D51.1
Billable Status
Yes — Valid for Submission
Code Describes
Vitamin B12 deficiency anemia due to selective vitamin B12 malabsorption with proteinuria
Short Description
Vit B12 defic anemia d/t slctv vit B12 malabsorp w protein
Parent Code
D51
Vitamin B12 deficiency anemia

Code Classification

ChapterD50–D89Diseases of the blood and blood-forming organs and certain disorders involving the immune mechanism
SectionD50-D53Nutritional anemias
CategoryD51Vitamin B12 deficiency anemia
This CodeD51.1Vitamin B12 deficiency anemia due to selective vitamin B12 malabsorption with proteinuria

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Familial megaloblastic anemia
  • Megaloblastic anemia due to inborn errors of metabolism
  • Megaloblastic anemia due to vitamin B>12< malabsorption with proteinuria
  • Pernicious anemia
  • Selective malabsorption of cyanocobalamin
  • Vitamin B12 deficiency anemia due to malabsorption with proteinuria

Tabular List NotesGuidance

Coding notes and annotation back-references applicable to this code.

Inclusion Terms

  • Imerslund (Gräsbeck) syndrome
  • Megaloblastic hereditary anemia

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • Anemia(essential) (general) (hemoglobin deficiency) (infantile) (primary) (profound)
      • deficiency
        • vitamin B12 NOS
          • due to
            • selective vitamin B12 malabsorption with proteinuria
    • Anemia(essential) (general) (hemoglobin deficiency) (infantile) (primary) (profound)
      • due to (in) (with)
        • selective vitamin B12 malabsorption with proteinuria
    • Anemia(essential) (general) (hemoglobin deficiency) (infantile) (primary) (profound)
      • megaloblastic
        • hereditary
    • Imerslund(-Gräsbeck) syndrome

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR BLD001
Nutritional anemia
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Anemia

If you have anemia, your blood does not carry enough oxygen to the rest of your body. The most common cause of anemia is not having enough iron. Your body needs iron to make hemoglobin. Hemoglobin is an iron-rich protein that gives the red color to blood. It carries oxygen from the lungs to the rest of the body.

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert D51.1 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
281.1 B12 defic anemia NEC
Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About D51.1Overview

Is D51.1 (Vitamin B12 deficiency anemia) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report vitamin B12 deficiency anemia due to selective vitamin B12 malabsorption with proteinuria on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does D51.1 group to?

When vitamin B12 deficiency anemia due to selective vitamin B12 malabsorption with proteinuria is the principal diagnosis on an inpatient stay, it groups to MS-DRG 811, 812, with relative weights from 0.9182 to 1.4043 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of D51.1?

Under the General Equivalence Mappings, vitamin B12 deficiency anemia due to selective vitamin B12 malabsorption with proteinuria converts to ICD-9-CM 281.1 (B12 defic anemia NEC). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Chronic - a chronic condition code indicates a condition lasting 12 months or longer and its effect on the patient based on one or both of the following criteria:

  • The condition results in the need for ongoing intervention with medical products,treatment, services, and special equipment
  • The condition places limitations on self-care, independent living, and social interactions.