K21.00 ICD-10-CM Code: Gastro-esophageal reflux disease with esophagitis, without bleeding
Billing Status: YES. This is a valid, specific, and billable ICD-10-CM reference.
Inpatient Payment Groups (MS-DRG)
MS-DRGs this diagnosis helps define, as principal or secondary, per the CMS ICD-10-CM/PCS MS-DRG Definitions Manual v43.0, Appendix B.
- MS-DRG 391 — ESOPHAGITIS, GASTROENTERITIS AND MISCELLANEOUS DIGESTIVE DISORDERS WITH MCC (MDC 06)
- MS-DRG 392 — ESOPHAGITIS, GASTROENTERITIS AND MISCELLANEOUS DIGESTIVE DISORDERS WITHOUT MCC (MDC 06)
A diagnosis appearing in a group's logic does not by itself determine the DRG assigned to a stay; the grouper uses the full claim.
Official Registry Overview & Definition
Official Tabular Instructional Notes
Sequencing, inclusion, and exclusion notes published for K21.00 in the official ICD-10-CM tabular list.
Inclusion Terms
Alternative terms the tabular list files under this code.
- Reflux esophagitis
Excludes1 — Not Coded Here
Conditions generally not reported together with this code (Excludes1) -- an error unless the two conditions are documented as unrelated to each other (ICD-10-CM Official Guidelines, Section I.A.12.a).
- newborn esophageal reflux (P78.83) Compare K21.00 vs P78.83 →
Excludes2 — Not Included Here
Conditions not covered by this code, but which may be reported alongside it when both are present.
- hiatus hernia (K44.-) Compare K21.00 vs K44 →
Frequently Compared Codes
The official Excludes notes on K21.00 name these codes. Each comparison page covers when the two can — or must not — be reported together.
Change history
- FY2021 — 2020-10-01Added to the code setGastro-esophageal reflux disease with esophagitis, without bleedingFY2021 changes
Verify Before Coding
- No Medicare Code Editor or MS-DRG Definitions Manual restrictions apply to this code.
From the code registry, the Medicare Code Editor, and the MS-DRG Definitions Manual. Check it against a full claim.
Contextual Map
Every relationship of K21.00 in one view: hierarchy, official tabular instructions in both directions, clinical classification, risk adjustment, MS-DRG participation, index terms and change history — each edge carrying the CMS source it derives from.
Hierarchy
- K00-K95 — Chapter 11: Diseases of the Digestive System (K00-K95) (K00-K95) [Hierarchy]
- K20-K31 — Diseases of esophagus, stomach and duodenum [Hierarchy]
Referenced by Excludes1 notes
- K20 — Esophagitis [Excludes1](via K21.0.-): “esophagitis with gastro-esophageal reflux disease (K21.0-)” · check together
Referenced by Code Also instructions
- R63.31 — Pediatric feeding disorder, acute [Code Also](via K21.-): “gastro-esophageal reflux disease (K21.-)” · check together
- R63.32 — Pediatric feeding disorder, chronic [Code Also](via K21.-): “gastro-esophageal reflux disease (K21.-)” · check together
Clinical classification (CCSR)
- DIG004 — Esophageal disorders [CCSR]
Potential MS-DRG
- DRG 391 — ESOPHAGITIS, GASTROENTERITIS AND MISCELLANEOUS DIGESTIVE DISORDERS WITH MCC [MS-DRG]: “ESOPHAGITIS, GASTROENTERITIS AND MISCELLANEOUS DIGESTIVE DISORDERS WITH MCC (MDC 06)”
- DRG 392 — ESOPHAGITIS, GASTROENTERITIS AND MISCELLANEOUS DIGESTIVE DISORDERS WITHOUT MCC [MS-DRG]: “ESOPHAGITIS, GASTROENTERITIS AND MISCELLANEOUS DIGESTIVE DISORDERS WITHOUT MCC (MDC 06)”
MDC crossing · procedures (5744)
- MDC 06 — Diseases and Disorders of the Digestive System [MDC crossing]: “Diseases and Disorders of the Digestive System — the grouper's crossing between diagnoses and procedures: a principal diagnosis sets the MDC, and same-MDC procedures move the stay to its surgical DRGs.”
- 008Q0ZZ — Division of Vagus Nerve, Open Approach [Same-MDC procedure]: “Division of Vagus Nerve, Open Approach — grouped in MDC 06, the procedure side of this code's crossing.” · check together
- 008Q3ZZ — Division of Vagus Nerve, Percutaneous Approach [Same-MDC procedure]: “Division of Vagus Nerve, Percutaneous Approach — grouped in MDC 06, the procedure side of this code's crossing.” · check together
- 008Q4ZZ — Division of Vagus Nerve, Percutaneous Endoscopic Approach [Same-MDC procedure]: “Division of Vagus Nerve, Percutaneous Endoscopic Approach — grouped in MDC 06, the procedure side of this code's crossing.” · check together
- 02BP3ZZ — Excision of Pulmonary Trunk, Percutaneous Approach [Same-MDC procedure]: “Excision of Pulmonary Trunk, Percutaneous Approach — grouped in MDC 06, the procedure side of this code's crossing.” · check together
- 02BQ3ZZ — Excision of Right Pulmonary Artery, Percutaneous Approach [Same-MDC procedure]: “Excision of Right Pulmonary Artery, Percutaneous Approach — grouped in MDC 06, the procedure side of this code's crossing.” · check together
- and 5739 more
Index entries
- Allergy, allergic (reaction) (to), milk protein, gastroesophageal reflux, with esophagitis (without bleeding)[Index term]
- Disease, diseased, gastroesophageal reflux (GERD), with esophagitis (without bleeding)[Index term]
- Esophagitis (acute) (alkaline) (chemical) (chronic) (infectional) (necrotic) (peptic) (postoperative) (without bleeding), due to gastrointestinal reflux disease (without bleeding)[Index term]
- Esophagitis (acute) (alkaline) (chemical) (chronic) (infectional) (necrotic) (peptic) (postoperative) (without bleeding), reflux[Index term]
- Reflux, esophageal, with esophagitis (without bleeding)[Index term]
- Reflux, gastroesophageal, with esophagitis (without bleeding)[Index term]
- Ulcer, ulcerated, ulcerating, ulceration, ulcerative, esophagus (peptic), due to, gastrointestinal reflux disease (without bleeding)[Index term]
Nearest codes
- K21 — Gastro-esophageal reflux disease [Sibling]
- K21.0 — Gastro-esophageal reflux disease with esophagitis [Sibling]
- K21.01 — Gastro-esophageal reflux disease with esophagitis, with bleeding [Sibling]
- K21.9 — Gastro-esophageal reflux disease without esophagitis [Sibling]
Change history
- FY2021 — Added to the code set [Change history]
Referenced by Other Codes
Clinical classification (AHRQ CCSR):DIG004 — Esophageal disorders (default).
Clinical Classifications Software Refined (CCSR) for ICD-10-CM Diagnoses. Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality.
Potential MS-DRG Relationships (FY2026)
Not on the CMS CC/MCC list — as a secondary diagnosis this code does not change MS-DRG severity.
Named in the grouper logic of 2 MS-DRGs: DRG 391 (MDC 06), DRG 392 (MDC 06).
From the CMS MS-DRG Definitions Manual (Appendices B and C). Actual DRG assignment depends on the complete claim.
Official ICD-10-CM tabular notes on other codes that name K21.00 or its code family.
1 Excludes1 notes: K20 (via K21.0.-).
2 Code Also instructions: R63.31 (via K21.-), R63.32 (via K21.-).
Nearest Codes in This Family
Official ICD-10-CM classifications closest to K21.00 in its code family, with their registry titles.
Indexed Clinical Terms (7)
Clinical term phrases from the official ICD-10-CM Index to Diseases and Injuries that map to this code.
- 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)