2026 ICD-10-CM Diagnosis Code D55.21Anemia due to pyruvate kinase deficiency

ICD-10-CM Codes›D50–D89›D55-D59›D55

ICD-10-CM D55.21
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

D55.21 is a billable ICD-10-CM diagnosis code for anemia due to pyruvate kinase deficiency. 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 HNSHA due to pyruvate kinase deficiency. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Hemolytic anemia.

D55.21 no longer risk-adjusts for Medicare Advantage: it mapped to HCC 48 under the retired CMS-HCC V24 model through payment year 2025 but maps to no category in the live V28 model. It still risk-adjusts in the PACE (CMS-HCC V22) category 48, ESRD (V21) category 48, and ESRD (V24) category 48 for payment year 2026.

Code Identity

ICD-10-CM Code
D55.21
Billable Status
Yes — Valid for Submission
Code Describes
Anemia due to pyruvate kinase deficiency
Short Description
Anemia due to pyruvate kinase deficiency
Same as the full description in the CMS dataset.
Parent Code
D55.2
Anemia due to disorders of glycolytic enzymes

Code Classification

ChapterD50–D89Diseases of the blood and blood-forming organs and certain disorders involving the immune mechanism
SectionD55-D59Hemolytic anemias
CategoryD55Anemia due to enzyme disorders
This CodeD55.21Anemia due to pyruvate kinase deficiency

Medicare Risk Adjustment (HCC)Billing

D55.21 no longer risk-adjusts for Medicare Advantage: it maps to no payment category in the live CMS-HCC V28 model, although it still risk-adjusts in the other CMS models shown below.

CMS-HCC V28 (Medicare Advantage Payment Model)
Not mapped
Dropped in V28 see all codes that no longer risk-adjust
Prior Model (CMS-HCC V24)
HCC 48
V24 retired last contributed to a Medicare Advantage risk score in payment year 2025
Other CMS Models
PACE (CMS-HCC V22): HCC 48 · ESRD (V21): HCC 48 · ESRD (V24): HCC 48
ESRD V21 weights: 0.059 dialysis, 0.173–0.234 functioning graft · ESRD V24 weights: 0.063 dialysis, 0.192–0.358 functioning graft
Part D (RxHCC)
Not mapped
D55.21 does not risk-adjust in the RxHCC prescription drug model

Source: CMS Payment Year 2026 risk adjustment mappings and model software. Weights are relative factors, not dollar amounts; a beneficiary's total RAF also includes demographics and interactions. Browse all CMS-HCC categories.

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • HNSHA due to pyruvate kinase deficiency

Tabular List NotesGuidance

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

Inclusion Terms

  • PK deficiency anemia
  • Pyruvate kinase deficiency anemia

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

Clinical ClassificationClinical

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

CCSR BLD002
Hemolytic 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.

Code History & ChangesHistory

Replacement D55.21 replaces the following previously assigned code(s):

  • D55.2 - Anemia due to disorders of glycolytic enzymes
FY 2022AddedAdded to the ICD-10-CM code setEffective October 1, 2021.
FY 2023–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About D55.21Overview

What is the ICD-10 code for anemia due to pyruvate kinase deficiency?

The ICD-10-CM code for anemia due to pyruvate kinase deficiency is D55.21 (sometimes written as D5521). It is billable on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

Is D55.21 (Anemia due to disorders of glycolytic enzymes) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report anemia due to pyruvate kinase deficiency on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does D55.21 group to?

When anemia due to pyruvate kinase deficiency 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.

Does D55.21 risk-adjust for Medicare Advantage payment?

Not for Medicare Advantage. D55.21 mapped to HCC 48 in the retired CMS-HCC V24 model, which last determined payment in 2025, but it maps to no category in the live V28 model; see all codes that no longer risk-adjust. It still risk-adjusts in the PACE (CMS-HCC V22) category 48 (Coagulation Defects and Other Specified Hematological Disorders), ESRD (V21) category 48 (Coagulation Defects and Other Specified Hematological Disorders), and ESRD (V24) category 48 (Coagulation Defects and Other Specified Hematological Disorders).