Question 1

What is ICD-10 code I38?

Accepted Answer

I38 is the ICD-10-CM diagnosis code for endocarditis, valve unspecified. An infection and inflammation of the inner lining of the heart (endocardium) affecting one or more heart valves, but the specific valve involved is not identified. I38 sits in the ICD-10-CM chapter for diseases of the circulatory system (i00-i99), within the section covering other forms of heart disease (i30-i5a).

I38 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.

This is a serious condition requiring identification of the causative organism when possible.

Question 2

Is I38 an HCC code?

Accepted Answer

No. I38 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 I38 billable?

Accepted Answer

Yes. I38 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. I38 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 I38?

Accepted Answer

I38 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 I38 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 I38?

Accepted Answer

This is a serious condition requiring identification of the causative organism when possible Always attempt to identify which valve is affected and the infectious agent to use more specific codes

I38

Is I38 an HCC code?

What This Code Means

Coding Tips

Includes

Excludes 1 — Do NOT code together

Code Hierarchy

Open I38 in the Interactive Encoder