I00 Rheumatic fever without heart involvement

The ICD-10-CM code for Rheumatic fever without heart involvement is I00 (FY2026). It is a billable, claim-ready diagnosis code.

Classification

Chapter

9: Diseases of the circulatory system (I00-I99)

Section

I00-I02: Acute rheumatic fever (I00-I02)

Category I00

1 code (1 billable)

FY2026 Status

Stable since FY2024

Also Known As

ICD-10-CM Alphabetic Index entries that lead to I00:

• Pneumonia (acute) (double) (migratory) (purulent) (septic) (unresolved) › rheumatic
• Rheumatic (acute) (subacute) › pneumonia
• Fever (inanition) (of unknown origin) (persistent) (with chills) (with rigor) › rheumatic (active) (acute) (chronic) (subacute)
• Erythema, erythematous (infectional) (inflammation) › marginatum › in (due to) acute rheumatic fever
• Pneumonia (acute) (double) (migratory) (purulent) (septic) (unresolved) › in (due to) › rheumatic fever

U.S. Hospital Utilization

• An estimated 665 U.S. inpatient stays in 2023 included I00 among the documented diagnoses.
• 135 stays listed it as the principal diagnosis.

Source: National Inpatient Sample (NIS), Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality, 2016–2023. National survey-weighted estimates.

Official Coding Guidelines

Presumed relationship due to Index term “with”

The classification presumes a causal relationship between hypertension and heart involvement and between hypertension and kidney involvement, as the two conditions are linked by the term “with” in the Alphabetic Index. These conditions should be coded as related even in the absence of provider documentation explicitly linking them, unless the documentation clearly states the conditions are unrelated.

Provider must link conditions not specifically indexed as related

For hypertension and conditions not specifically linked by relational terms such as “with,” “associated with” or “due to” in the classification, provider documentation must link the conditions in order to code them as related.

Source: CMS — ICD-10-CM Official Guidelines for Coding and Reporting, FY2026

References

• CMS — ICD-10-CM Official Code Set and Guidelines, FY2026
• CDC/NCHS — ICD-10-CM Files and Browser Tool
• AHRQ — HCUP National Inpatient Sample, Frequencies by Diagnosis Code (2016–2023)

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I00 — Rheumatic fever without heart involvement. ICD-10 Coding Pro (ICD-10-CM FY2026). https://icd10codingpro.com/codes/I00

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