Question 1

What is ICD-10 code H00.021?

Accepted Answer

H00.021 is the ICD-10-CM diagnosis code for hordeolum internum right upper eyelid. A painful infection or swelling of the inner eyelid structures on the right upper eyelid, typically involving the meibomian glands. H00.021 sits in the ICD-10-CM chapter for diseases of the eye and adnexa (h00-h59), within the section covering disorders of eyelid, lacrimal system and orbit (h00-h05).

H00.021 is a billable ICD-10-CM code but does not map to a payment HCC under the CMS-HCC V28, V24, ESRD, or RxHCC risk adjustment models. It can be reported on Medicare Advantage encounter data submissions but it does not contribute to a beneficiary's RAF score and therefore does not affect risk-adjusted payments to the plan.

Hordeolum internum affects internal eyelid structures (meibomian glands); this is more serious than external hordeolum.

Question 2

Is H00.021 an HCC code?

Accepted Answer

No. H00.021 is a billable ICD-10-CM code but does not map to any payment HCC category under the CMS-HCC V28, V24, ESRD, or RxHCC risk adjustment models. It can still be reported on Medicare Advantage encounter data submissions, but it does not contribute to the beneficiary's Risk Adjustment Factor (RAF) score and therefore does not affect the risk-adjusted capitation payment to the plan. V28 reached 100% phase-in for payment year 2026.

Question 3

Is H00.021 billable?

Accepted Answer

Yes. H00.021 is a billable ICD-10-CM code that can be reported on professional and institutional claims as a primary or secondary diagnosis when the provider documentation supports the specific condition described. Billable codes in ICD-10-CM are coded to the highest level of specificity available for the documented diagnosis. H00.021 is current for fiscal year 2026 and remains in the active CMS ICD-10-CM code set published by the National Center for Health Statistics.

Question 4

What is the V28 vs V24 difference for H00.021?

Accepted Answer

H00.021 does not map to a payment HCC under either the CMS-HCC V28 risk adjustment model or the older V24 model. V28 reached 100% phase-in for payment year 2026, replacing V24 which was used during the PY2024–PY2025 transition. Because neither model rewards H00.021 with a risk adjustment factor, it contributes zero to a Medicare Advantage beneficiary's RAF score in either version. Coders should check whether provider documentation supports a more specific child code that does map to a payment HCC.

Question 5

What should coders know when reporting H00.021?

Accepted Answer

Hordeolum internum affects internal eyelid structures (meibomian glands); this is more serious than external hordeolum Ensure both laterality (right eye) and eyelid location (upper) are clearly documented in the medical record

HCC Buddy Code Card

H00.021

Is H00.021 an HCC code?

Get the V28 RAF + MEAT cheat sheet

What This Code Means

Coding Tips

Child Codes

Code Hierarchy

Work H00.021 in HCC Buddy

H00.021 ICD-10-CM Code: Hordeolum internum right upper eyelid

HCC Buddy Code Card

H00.021

Is H00.021 an HCC code?

Get the V28 RAF + MEAT cheat sheet

What This Code Means

Coding Tips

Child Codes

Code Hierarchy

Work H00.021 in HCC Buddy