ICD-10 K21.0
Non-Billable HeaderGastro-esophageal reflux disease with esophagitis
About ICD-10-CM K21.0
ICD-10-CM code K21.0 represents Gastro-esophageal reflux disease with esophagitis. This is a non-billable header code in the Digestive System chapter (block K21). The 2026 edition of ICD-10-CM K21.0 became effective on October 1, 2025. Non-billable codes cannot be used as a primary or secondary diagnosis on a claim, use a more specific child code instead.
Medicare LCD Coverage for K21.0
Local Coverage Determinations (LCDs) from CMS MACs that list K21.0 as a covered diagnosis.
This doesn't mean the code isn't covered, it means no MAC has issued a Local Coverage Determination naming this specific code. Coverage may still apply under National Coverage Determinations or general medical-necessity rules.
Commercial Payer Coverage
Coverage policies from major commercial payers referencing K21.0.
Our payer policy database covers Aetna, Cigna, Anthem, BCBS, Humana, and Medicare Advantage plans, but K21.0 doesn't currently appear in any indexed policy. The code may still be covered under standard plan benefits.
CPT Codes Commonly Billed with K21.0
Procedures frequently paired with this diagnosis based on PayerReady's Dx↔Px linkage data.
- 43239 EGD with biopsy — abdominal pain, GERD, gastritis, ulcer Gastroenterology
- 45378 Upper GI endoscopy Gastroenterology
- 45380 Colonoscopy Gastroenterology
- 45384 ERCP Gastroenterology
- 90654 Vaccine administration Gastroenterology
- 99152 Moderate sedation Gastroenterology
- 45350 Flexible sigmoidoscopy Gastroenterology
- 99203 New patient office visit — common complaints plus chronic conditions: HTN, diabetes, hyperlipidemia, asthma, GERD, back pain, migraine, tachycardia, prediabetes Primary Care
- 99213 Established patient — HTN follow-up, diabetes management, hyperlipidemia, asthma, anxiety, common complaints, back pain, GERD, migraine, acne, joint pain, prediabetes, obesity, anemia, hypothyroid, fatigue Primary Care
- 43235 Diagnostic EGD — abdominal pain, nausea, vomiting, GERD, gastric ulcer, gastritis, hematemesis, melena, Barrett esophagus, dysphagia, esophagitis, weight loss, iron deficiency anemia, polyp Gastroenterology
Convert K21.0 to ICD-9-CM
Per CMS General Equivalence Mappings (GEMs), useful for legacy data review and historical claim analysis.
| ICD-10 | ICD-9 | Mapping Flags |
|---|---|---|
| K21.0 | 53011 | 00000 |
Flags format (5 digits): Approximate · No Map · Combination · Scenario · Choice List. Source: CMS 2017 GEMs (final version).
Codes Adjacent To K21.0
Other codes in section K20-K31 (Diseases of esophagus, stomach and duodenum).
ICD-10 K21.0, Billing FAQ
Is ICD-10 code K21.0 billable? +
No, K21.0 is a non-billable header code. Use a more specific child code from block K21 when submitting claims.
What CPT codes are commonly billed with K21.0? +
Procedures frequently paired with K21.0 include: 43239, 45378, 45380, 45384, 90654.
What ICD-9 codes does K21.0 map to? +
Per CMS GEMs, K21.0 maps to ICD-9 codes: 53011. Useful for legacy data review and historical claim analysis.
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Reviewed by the PayerReady Medical Coding Team
Verified against the CMS 2026 code set on May 31, 2026.
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