ICD-10 E21.5
Billable / Specific HCC v28: 23Disorder of parathyroid gland, unspecified
About ICD-10-CM E21.5
ICD-10-CM code E21.5 represents Disorder of parathyroid gland, unspecified. This is a billable/specific code in the Endocrine, Nutritional, and Metabolic chapter (block E21). The 2026 edition of ICD-10-CM E21.5 became effective on October 1, 2025.
Coding Tips for E21.5
Specialist guidance from the PayerReady Medical Coding Team. Specificity warnings, HCC capture rules, sequencing notes.
E21.5 is a CMS-HCC v28 risk-adjustment code (category 23). To count for the patient Risk Adjustment Factor (RAF), document the diagnosis with MEAT language each calendar year: Monitored, Evaluated, Assessed, Treated. A diagnosis on the problem list alone does not satisfy CMS RADV audit standards. Include the diagnosis in the assessment with current status and current treatment plan.
Medicare Advantage HCC Impact
Capture this diagnosis annually for accurate risk adjustment. Missed HCC captures are the #1 revenue leak in Medicare Advantage risk programs.
Medicare LCD Coverage for E21.5
Local Coverage Determinations (LCDs) from CMS MACs that list E21.5 as a covered diagnosis.
Showing top 10 of 49 total . Click a CPT for full coverage scope.
Commercial Payer Coverage
Coverage policies from major commercial payers referencing E21.5.
1 Cigna
2 Medicare
1 Aetna
CPT Codes Commonly Billed with E21.5
Procedures frequently paired with this diagnosis based on PayerReady's Dx↔Px linkage data.
We don't have CPT pairings indexed for this specific code yet. Use the CPT search above to find common procedures, or check your payer's published medical policy for code-specific guidance.
Convert E21.5 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 |
|---|---|---|
| E21.5 | 2529 | 00000 |
Flags format (5 digits): Approximate · No Map · Combination · Scenario · Choice List. Source: CMS 2017 GEMs (final version).
Codes Adjacent To E21.5
Other codes in section E20-E35 (Disorders of other endocrine glands).
ICD-10 E21.5, Billing FAQ
Is ICD-10 code E21.5 billable? +
Yes, E21.5 is a billable ICD-10-CM code that can appear as a primary or secondary diagnosis on claims.
Does E21.5 affect Medicare Advantage HCC risk adjustment? +
Yes. E21.5 maps to CMS-HCC v28 category 23. Capture this diagnosis annually for accurate Medicare Advantage risk score.
What ICD-9 codes does E21.5 map to? +
Per CMS GEMs, E21.5 maps to ICD-9 codes: 2529. 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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