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I00 ICD-10-CM Code: Rheumatic fever without heart involvement

Billing Status: YES. This is a valid, specific, and billable ICD-10-CM reference.

Coding at a Glance

Tabular directives
1 inclusion term · 1 Excludes1

Inpatient Payment Groups (MS-DRG)

Potential MS-DRG participation — not a DRG assignment.

MS-DRGs this diagnosis helps define, as principal or secondary, per the CMS ICD-10-CM/PCS MS-DRG Definitions Manual v43, Appendix B.

  • MS-DRG 545 — CONNECTIVE TISSUE DISORDERS WITH MCC (MDC 08)
  • MS-DRG 546 — CONNECTIVE TISSUE DISORDERS WITH CC (MDC 08)
  • MS-DRG 547 — CONNECTIVE TISSUE DISORDERS WITHOUT CC/MCC (MDC 08)

A diagnosis appearing in a group's logic does not by itself determine the DRG assigned to a stay; the grouper uses the full claim.

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for I00 in the official ICD-10-CM tabular list, quoted as published.

Source: CMS/CDC — ICD-10-CM Tabular ListRelease: FY2026Effective: October 1, 2025

Includes

Conditions the official ICD-10-CM tabular list includes under this code.

  • arthritis, rheumatic, acute or subacute

Excludes1 — Not Coded Here

Conditions generally not reported together with this code (Excludes1) -- an error unless the two conditions are documented as unrelated to each other (ICD-10-CM Official Guidelines, Section I.A.12.a).

Coder workflow for I00

MedCoder structured workflow — derived from this code’s own official record

Before you code I00

  1. Check the Excludes1 note: if the documentation supports a condition named there, do not simply proceed with I00. Excludes1 conditions are not reported together with this code unless the record shows they are unrelated (Guidelines I.A.12.a).

    See the official tabular notes

Choose the right path

  1. Does the documentation support a condition named in I00’s Excludes1 note?
    Yes → Do not simply proceed: review the excluded code. Both are reported only when the record shows the two conditions are unrelated.
    No → Continue.

Consider I00. Then confirm the code is valid for the date of service in the Verify section.

Documentation check

The provider’s diagnostic statement
Codes are assigned from the provider’s documented diagnosis, not from clinical criteria, test values or a medication list (Guidelines I.A.19).
The associated condition or complication
Whether the associated condition the title names is documented; the “with” convention presumes some links, and a provider statement that the conditions are unrelated defeats it (Guidelines I.A.15).

Official instructions as workflow

  • Excludes1 — check before selecting I00(1 note)

    Coding workflow: If the documentation supports a condition named in this note, do not simply proceed with I00: the two are not reported together. The one exception is when the record shows the two conditions are unrelated to each other.

    See the official tabular notes · Guidelines I.A.12.a

Coding decision scenarios

Pattern scenarios for this code’s structure — decision rules, not clinical cases

Documentation: Both the condition I00 describes and a condition named in its Excludes1 note are documented for the same encounter.

Coding question: Can both codes be reported?

Path: Review the Excludes1 note and the excluded code, and look for a provider statement on whether the two conditions are related.

Reason: Excludes1 means the two are not coded together; the exception is when the record shows the conditions are unrelated to each other (Guidelines I.A.12.a).

Every row is derived from this code’s own record — its title, tabular notes, 7th-character family and same-category siblings — with fixed MedCoder wording; nothing is inferred about a patient. The official notes and guideline text are in the sections each row links to, and they control.

Code Overview

Rheumatic fever without heart involvement is a billable ICD-10-CM diagnosis code (I00).

MedCoder summary Summary composed by MedCoder from this code's official ICD-10-CM record. The tabular instructional notes themselves appear verbatim below.

Indexed Clinical Terms (5)

Official source data — entries quoted as published, in the Index’s own lookup phrasing

Clinical term phrases from the official ICD-10-CM Index to Diseases and Injuries that map to this code. These are alphabetic-index entries shown as the Index writes them — lookup phrasing, not necessarily the wording of a final diagnosis.

Verify Before Coding

  • No Medicare Code Editor or MS-DRG Definitions Manual restrictions apply to this code.

From the code registry, the Medicare Code Editor, and the MS-DRG Definitions Manual. Check it against a full claim in Claim Check.

Relationships & Classification

MedCoder structured relationships — computed from published CMS and AHRQ datasets

Other codes that name I00 or its code family, from the CMS ICD-10-CM tabular instructional notes. Tabular-note edges are stored at the code family level that carries each note.

Referenced by 2 Excludes1 notes: M02 — Postinfective and reactive arthropathies, M05 — Rheumatoid arthritis with rheumatoid factor.

These codes’ tabular lists mark this diagnosis as mutually exclusive — not reported together unless the conditions are documented as unrelated.

Referenced by 12 Excludes2 notes across 2 chapters: I51 — Complications and ill-defined descriptions of heart disease, J09 — Influenza due to certain identified influenza viruses, J09-J18 — Influenza and pneumonia (J09-J18), J10 — Influenza due to other identified influenza virus, J11 — Influenza due to unidentified influenza virus, J12 — Viral pneumonia, not elsewhere classified, J13 — Pneumonia due to Streptococcus pneumoniae, J14 — Pneumonia due to Hemophilus influenzae, J15 — Bacterial pneumonia, not elsewhere classified, J16 — Pneumonia due to other infectious organisms, not elsewhere classified, J17 — Pneumonia in diseases classified elsewhere, J18 — Pneumonia, unspecified organism.

These codes’ tabular lists name this diagnosis as distinct — both may be reported when both are documented.

Referenced by 1 Code First instruction: J17 — Pneumonia in diseases classified elsewhere.

Each of these codes carries a Code First note naming this condition — when that code is reported, THIS code is sequenced first, ahead of it.

MS-DRG Grouper Relationships (FY2026)

Potential MS-DRG participation — not a DRG assignment.

FY2026 MS-DRG: not on the CMS CC/MCC list — as a secondary diagnosis this code does not change MS-DRG severity for that release.

Named in the grouper logic of 3 MS-DRGs: DRG 545 (MDC 08), DRG 546 (MDC 08), DRG 547 (MDC 08).

From the CMS MS-DRG Definitions Manual (Appendices B and C). Actual DRG assignment depends on the complete claim.

Clinical classification (AHRQ CCSR):CIR002 — Acute rheumatic heart disease (default); INF003 — Bacterial infections.

Clinical Classifications Software Refined (CCSR) for ICD-10-CM Diagnoses. Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality.

Related Codes

Same clinical category (CCSR)

AHRQ's Clinical Classifications Software groups these diagnoses under the same clinical categories (Acute rheumatic heart disease, Bacterial infections).

I01.0 — Acute rheumatic pericarditis, I01.1 — Acute rheumatic endocarditis, I01.2 — Acute rheumatic myocarditis, I01.8 — Other acute rheumatic heart disease, I01.9 — Acute rheumatic heart disease, unspecified, I02.0 — Rheumatic chorea with heart involvement, I02.9 — Rheumatic chorea without heart involvement, +398 more

Same Index main term, other category

The ICD-10-CM Index to Diseases and Injuries files this code under the main terms “Fever”, “Rheumatic”, “Pneumonia”, …; these codes share that main term but sit in a different category of the Tabular List.

B65.2 — Schistosomiasis due to Schistosoma japonicum (Katayama), B65.9 — Schistosomiasis, unspecified (in, schistosomiasis), B77.81 — Ascariasis pneumonia (Ascaris), B83.9 — Helminthiasis, unspecified (worm), B99 — Other and unspecified infectious diseases (postinfectional NEC), B99.8 — Other infectious disease (infective, specified NEC), B99.9 — Unspecified infectious disease (infective), D70.9 — Neutropenia, unspecified (neutropenic), D86.89 — Sarcoidosis of other sites (uveoparotid), E52 — Niacin deficiency [pellagra] (endemic), I01 — Rheumatic fever with heart involvement (rheumatic, active with heart involvement), I01.0 — Acute rheumatic pericarditis (pericarditis), I01.2 — Acute rheumatic myocarditis (myocarditis, active or acute), I01.8 — Other acute rheumatic heart disease (coronary arteritis), I02.0 — Rheumatic chorea with heart involvement (myocarditis, with chorea), I02.9 — Rheumatic chorea without heart involvement (rheumatic, with central nervous system involvement), I05.9 — Rheumatic mitral valve disease, unspecified (rheumatic, inactive or quiescent with, endocarditis, mitral), I06.9 — Rheumatic aortic valve disease, unspecified (rheumatic, inactive or quiescent with, endocarditis, aortic), I07.8 — Other rheumatic tricuspid valve diseases (rheumatic, inactive or quiescent with, endocarditis, tricuspid), I08.0 — Rheumatic disorders of both mitral and aortic valves (rheumatic, inactive or quiescent with, endocarditis, mitral, with aorticdisease), +241 more

Contextual Map

Every relationship of I00 in one view: hierarchy, official tabular instructions in both directions, clinical classification, risk adjustment, MS-DRG participation, index terms and change history — each edge carrying the CMS source it derives from.

Run I00 with these 16 related codes in Claim Check

Hierarchy

Excludes1

Referenced by Excludes1 notes

Referenced by Excludes2 notes (12)

Referenced by Code First instructions

Clinical classification (CCSR)

MS-DRG Grouper

MDC crossing

  • MDC 08 — Diseases and Disorders of the Musculoskeletal System and Connective Tissue[MDC crossing]: “Diseases and Disorders of the Musculoskeletal System and Connective Tissue — the grouper's crossing between diagnoses and procedures: a principal diagnosis sets the MDC, and same-MDC procedures move the stay to its surgical DRGs. 18,508 same-MDC procedures group here; browse them on the MDC page.”— CMS MS-DRG Definitions Manual · FY2026

Index entries

  • Erythema, erythematous (infectional) (inflammation), marginatum, inacute rheumatic fever (due to)[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Fever (inanition) (of unknown origin) (persistent) (with chills) (with rigor), rheumatic (active) (acute) (chronic) (subacute)[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Pneumonia (acute) (double) (migratory) (purulent) (septic) (unresolved), in (due to), rheumatic fever[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Pneumonia (acute) (double) (migratory) (purulent) (septic) (unresolved), rheumatic[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Rheumatic (acute) (subacute), pneumonia[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026

Change history

  • FY2016 — In the code set at ICD-10-CM adoption [Change history]— CMS release files (code change ledger) · icd10cm-fy2016

Sources for this page

Codes, titles, notes, index terms and mappings on this page are transcribed from the datasets below. Relationships MedCoder computed and text MedCoder wrote are labelled where they appear.

Code, title, tabular notes and index terms Official source data
CMS/CDC ICD-10-CM FY2026 tabular list, index and tables, effective October 1, 2025 Release, file and checksum · Publisher’s page
Claim edits Official source data
CMS Definitions of Medicare Code Edits — v43.1 (April 2026) Release, file and checksum · Publisher’s page
Inpatient payment groups Official source data
CMS MS-DRG Definitions Manual (incl. Appendix B diagnosis index, Appendix C CC/MCC list, Appendix E procedure index) and IPPS Final Rule tables — v43 Release, file and checksum · Publisher’s page
Change history and date-of-service validity Official source data
CMS ICD-10-CM release addenda, ingested release by release into the change ledger Release, file and checksum · Publisher’s page
Comparisons, relationships and the contextual map MedCoder structured relationship
Computed by MedCoder from the tabular notes and tables above; every derived relationship is marked as derived where it appears
Summary and FAQ answers MedCoder explanation
Written by MedCoder to explain the sources above: drafted with AI assistance, checked by a person against the release files, and labelled as MedCoder text where it appears. Not official text.

Labels on this page: Official source data · MedCoder structured relationship · MedCoder explanation. How to read the labels · All data sources and release dates

Change history

  • FY2016 — October 1, 2015
    In the code set at ICD-10-CM adoption
    Rheumatic fever without heart involvement

No changes since FY2016 — additions, deletions, description changes and billable-status changes are tracked through FY2027 (effective October 1, 2026), and none are recorded for this code. Note changes are tracked from FY2027 only.