2026 ICD-10-CM Diagnosis Code K21.00Gastro-esophageal reflux disease with esophagitis, without bleeding

ICD-10-CM Codes›K00–K95›K20-K31›K21

ICD-10-CM K21.00
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

K21.00 is a billable ICD-10-CM diagnosis code for gastro-esophageal reflux disease with esophagitis, without bleeding. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 391 through 392. Coders also document this condition as alkaline reflux disease. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Esophageal disorders.

Code Identity

ICD-10-CM Code
K21.00
Billable Status
Yes — Valid for Submission
Code Describes
Gastro-esophageal reflux disease with esophagitis, without bleeding
Short Description
Gastro-esophageal reflux dis with esophagitis, without bleed
Parent Code
K21.0
Gastro-esophageal reflux disease with esophagitis

Code Classification

ChapterK00–K95Diseases of the digestive system
SectionK20-K31Diseases of esophagus, stomach and duodenum
CategoryK21Gastro-esophageal reflux disease
This CodeK21.00Gastro-esophageal reflux disease with esophagitis, without bleeding

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Alkaline reflux disease
  • Esophagogastric ulcer
  • Gastro-esophageal reflux disease with esophagitis
  • Gastro-esophageal reflux disease with ulceration
  • Gastroesophagitis
  • Lower esophageal stenosis due to erosive gastro-esophageal reflux disease

Tabular List NotesGuidance

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

Inclusion Terms

  • Reflux esophagitis

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.

    • Allergy, allergic(reaction) (to)
      • milk protein
        • gastroesophageal reflux
          • with esophagitis (without bleeding)
    • Disease, diseased
      • gastroesophageal reflux (GERD)
        • with esophagitis (without bleeding)
    • Esophagitis(acute) (alkaline) (chemical) (chronic) (infectional) (necrotic) (peptic) (postoperative) (without bleeding)
      • due to gastrointestinal reflux disease (without bleeding)
    • Esophagitis(acute) (alkaline) (chemical) (chronic) (infectional) (necrotic) (peptic) (postoperative) (without bleeding)
      • reflux
    • Reflux
      • esophageal
        • with esophagitis (without bleeding)
    • Reflux
      • gastroesophageal
        • with esophagitis (without bleeding)
    • Ulcer, ulcerated, ulcerating, ulceration, ulcerative
      • esophagus (peptic)
        • due to
          • gastrointestinal reflux disease (without bleeding)

Clinical ClassificationClinical

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

CCSR DIG004
Esophageal disorders
Default principal diagnosis: inpatient Yes · outpatient Yes

Patient EducationClinical

Eosinophilic Esophagitis

Eosinophilic esophagitis (EoE) is a chronic disease of the esophagus. Your esophagus is the muscular tube that carries food and liquids from your mouth to the stomach. If you have EoE, white blood cells called eosinophils build up in your esophagus.

The full article covers:

  • What is eosinophilic esophagitis (EoE)?
  • What causes eosinophilic esophagitis (EoE)?
  • Who is at risk for eosinophilic esophagitis(EoE)?
  • What are the symptoms of eosinophilic esophagitis (EoE)?
  • How is eosinophilic esophagitis (EoE) diagnosed?
  • What are the treatments for eosinophilic esophagitis (EoE)?

Read the full article at MedlinePlus

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

Code History & ChangesHistory

Replacement K21.00 replaces the following previously assigned code(s):

  • K21.0 - Gastro-esophageal reflux disease with esophagitis
FY 2021AddedAdded to the ICD-10-CM code setEffective October 1, 2020.
FY 2022–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About K21.00Overview

Is K21.00 (Gastro-esophageal reflux disease with esophagitis) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report gastro-esophageal reflux disease with esophagitis, without bleeding on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does K21.00 group to?

When gastro-esophageal reflux disease with esophagitis, without bleeding is the principal diagnosis on an inpatient stay, it groups to MS-DRG 391, 392, with relative weights from 0.7796 to 1.2683 depending on complications. Higher weights mean higher Medicare reimbursement.

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.