Skip to main content

A43.0 ICD-10-CM Code: Pulmonary nocardiosis

Compare with another codeCheck this code on a claim

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

Coding at a Glance

Risk adjustment
CMS-HCC V22 category 115

Billable · FY2027A valid, specific ICD-10-CM code, reportable for dates of service in FY2027.

What you need to know

Source: CMS/NCHS Official ICD-10-CM tabular notes, quoted. From the CMS/NCHS tabular list for the release in force. A note the category or block publishes applies to this code too; the Instructions section marks which is which.

The tabular list publishes no instructional note for this code itself.

CompareCheck ClaimView Related Codes

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 v44, Appendix B.

  • MS-DRG 177 — RESPIRATORY INFECTIONS AND INFLAMMATIONS WITH MCC (MDC 04)
  • MS-DRG 178 — RESPIRATORY INFECTIONS AND INFLAMMATIONS WITH CC (MDC 04)
  • MS-DRG 179 — RESPIRATORY INFECTIONS AND INFLAMMATIONS WITHOUT CC/MCC (MDC 04)
  • MS-DRG 974 — HIV WITH MAJOR RELATED CONDITION WITH MCC (MDC 25)
  • MS-DRG 975 — HIV WITH MAJOR RELATED CONDITION WITH CC (MDC 25)
  • MS-DRG 976 — HIV WITH MAJOR RELATED CONDITION WITHOUT CC/MCC (MDC 25)

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 context

The comparisons, hierarchy, index entries, guidelines, relationships, risk-adjustment and coverage context a coder commonly needs. Each section names whether it is official source data, a MedCoder-derived relationship or MedCoder editorial.

Don’t confuse A43.0 with…

MedCoder analysis — pairs from this code’s official notes, distinctions written by MedCoder

The codes most likely to be picked instead of A43.0 — named in its own official notes, or sharing its laterality or encounter family — with what separates them and which documentation moves the case. Each links to the full comparison.

  • A43.9— Specificity relationship (Review)

    Overlapping diagnoses in the same category.

    Overlapping codes in the same category — the documentation decides which is the more specific fit.

    What moves you there: A record that documents no more than “Nocardiosis, unspecified” takes A43.9; specificity in the record moves it back here.

    Full comparison: A43.0 vs A43.9 →

Relationships are read from this code's own official notes, its laterality siblings and its encounter family; the wording of each distinction is MedCoder editorial, and the documentation named in each “what moves you there” line is the official note phrase or sibling title itself. Source: CMS ICD-10-CM tabular instructional notes; ICD-10-CM Official Guidelines, Section I.A.12.a.

Code Overview

Pulmonary nocardiosis is a billable ICD-10-CM diagnosis code (A43.0).

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 (4)

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

  • CC as a secondary diagnosis (FY2027). Can raise the stay's MS-DRG severity tier.

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-derived relationships — computed from published CMS and AHRQ datasets

Other codes that name A43.0 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 1 Excludes1 note: J17 — Pneumonia in diseases classified elsewhere.

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

MS-DRG Grouper Relationships (FY2027)

Potential MS-DRG participation — not a DRG assignment.

FY2027 MS-DRG: CC — Complication or Comorbidity. Reported as a secondary diagnosis, this code raises the stay's MS-DRG severity tier — except when the principal diagnosis is one of 10 clinically related codes on its CMS exclusion list. Does not count toward severity when the stay groups to DRGs 974-976 (HIV with Major Related Condition).

Named in the grouper logic of 6 MS-DRGs: DRG 177 (MDC 04), DRG 178 (MDC 04), DRG 179 (MDC 04), DRG 974 (MDC 25), DRG 975 (MDC 25), DRG 976 (MDC 25).

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

Clinical classification (AHRQ CCSR):RSP002 — Pneumonia (except that caused by tuberculosis) (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 process (MS-DRG)

Acts as CC — raises the severity of other admissions. CMS groups these diagnoses into one MS-DRG principal-diagnosis exclusion process — a CC/MCC on this list never raises severity when the principal diagnosis is also on it.

A42.0 — Pulmonary actinomycosis, A42.81 — Actinomycotic meningitis, A42.82 — Actinomycotic encephalitis, A42.89 — Other forms of actinomycosis, A42.9 — Actinomycosis, unspecified, A43.8 — Other forms of nocardiosis, A43.9 — Nocardiosis, unspecified, B47.1 — Actinomycetoma, J12.81 — Pneumonia due to SARS-associated coronavirus

Same clinical category (CCSR)

AHRQ's Clinical Classifications Software groups these diagnoses under the same clinical categories (Pneumonia (except that caused by tuberculosis), Bacterial infections).

A01.03 — Typhoid pneumonia, A02.22 — Salmonella pneumonia, A20.2 — Pneumonic plague, A21.2 — Pulmonary tularemia, A22.1 — Pulmonary anthrax, A31.0 — Pulmonary mycobacterial infection, A37.01 — Whooping cough due to Bordetella pertussis with pneumonia, A37.11 — Whooping cough due to Bordetella parapertussis with pneumonia, A37.81 — Whooping cough due to other Bordetella species with pneumonia, A37.91 — Whooping cough, unspecified species with pneumonia, A48.1 — Legionnaires' disease, A50.04 — Early congenital syphilitic pneumonia, A52.72 — Syphilis of lung and bronchus, A54.84 — Gonococcal pneumonia, B01.2 — Varicella pneumonia, B05.2 — Measles complicated by pneumonia, B06.81 — Rubella pneumonia, B25.0 — Cytomegaloviral pneumonitis, B37.1 — Pulmonary candidiasis, B38.0 — Acute pulmonary coccidioidomycosis, +418 more

Same Index main term, other category

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

A02.22 — Salmonella pneumonia (Salmonella), A20.2 — Pneumonic plague (in, Yersinia pestis), A21.2 — Pulmonary tularemia (tularemic), A22.1 — Pulmonary anthrax (anthrax), A24.1 — Acute and fulminating melioidosis (in, Pseudomonas NEC, pseudomallei), A37.01 — Whooping cough due to Bordetella pertussis with pneumonia (in, whooping cough, due to, Bordetella pertussis), A37.11 — Whooping cough due to Bordetella parapertussis with pneumonia (in, whooping cough, due to, Bordetella parapertussis), A37.81 — Whooping cough due to other Bordetella species with pneumonia (in, whooping cough, due to, specified NEC), A37.91 — Whooping cough, unspecified species with pneumonia (in, whooping cough), A42.0 — Pulmonary actinomycosis (in, actinomycosis), A50.04 — Early congenital syphilitic pneumonia (alba), A54.84 — Gonococcal pneumonia (gonococcal), A69.8 — Other specified spirochetal infections (spirochetal NEC), A70 — Chlamydia psittaci infections (psittacosis), A78 — Q fever (in, Q fever), B01.2 — Varicella pneumonia (varicella), B05.2 — Measles complicated by pneumonia (giant cell), B06.81 — Rubella pneumonia (in, rubella), B25.0 — Cytomegaloviral pneumonitis (cytomegaloviral), B37.1 — Pulmonary candidiasis (Candida), +82 more

Lab tests where this diagnosis supports Medicare coverage (NCD)

Medicare's National Coverage Determination (NCD) program lists this diagnosis as medical justification for these lab tests.

HIV Screening Test

Contextual Map

Every relationship of A43.0 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 A43.0 with this related code in Claim Check

Hierarchy

Referenced by Excludes1 notes

Clinical classification (CCSR)

MS-DRG Grouper

MDC crossing

  • MDC 04 — Diseases and Disorders of the Respiratory System[MDC crossing]: “Diseases and Disorders of the Respiratory System — 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. 4,000 same-MDC procedures group here; browse them on the MDC page.”— CMS MS-DRG Definitions Manual · FY2027
  • MDC 25 — Human Immunodeficiency Virus Infections[MDC crossing]: “Human Immunodeficiency Virus Infections — 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.”— CMS MS-DRG Definitions Manual · FY2027

Index entries

  • Nocardiosis, nocardiasis, lung[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Nocardiosis, nocardiasis, pneumonia[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Nocardiosis, nocardiasis, pulmonary[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Pneumonia (acute) (double) (migratory) (purulent) (septic) (unresolved), in (due to), nocardiosis, nocardiasis[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027

Nearest codes

Change history

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

Deep reference

Published questions and FAQ, every source behind this page with its release and checksum, the date-of-service check and the complete change history.

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 FY2027 tabular list, index and tables, effective October 1, 2026 Release, file and checksum · Publisher’s page
Claim edits Official source data
CMS Definitions of Medicare Code Edits — v44.0 (October 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 — v44 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-derived 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 editorial 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.

Current data releases:ICD-10-CM FY2027 · ICD-10-PCS FY2027 · HCPCS October 2026 · MS-DRG v44 · Medicare Code Editor v44.0 · NCCI PTP Q4 2026 · MUE Q4 2026 · NCD code lists 2026-01 · LCD export September 20, 2026 · All releases and sources

Labels on this page: Official source data · MedCoder-derived relationship · MedCoder editorial explanation. How to read the labels · All data sources and release dates · CMS coding rules

Cite this page

Reference this page in a research guide, syllabus or article. The release is included because code content changes each year.

MedCoder.ai. "A43.0 — Pulmonary nocardiosis." ICD-10-CM FY2027. https://medcoder.ai/icd10/code/a43.0-pulmonary-nocardiosis

Change history

  • FY2016 — October 1, 2015
    In the code set at ICD-10-CM adoption
    Pulmonary nocardiosis

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

Nearest Codes in This Family

Official ICD-10-CM classifications closest to A43.0 in its code family, with their registry titles.

View all codes in the A43 family