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E84.9 ICD-10-CM Code: Cystic fibrosis, unspecified

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

Coding at a Glance

Tabular directives
1 inclusion term · 5 Excludes1 · 1 Excludes2 · 1 code-also instruction
Risk adjustment
CMS-HCC V28: 1 category · CMS-HCC V22 category 110 · RxHCC V08 category 225

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 640 — MISCELLANEOUS DISORDERS OF NUTRITION, METABOLISM, FLUIDS AND ELECTROLYTES WITH MCC (MDC 10)
  • MS-DRG 641 — MISCELLANEOUS DISORDERS OF NUTRITION, METABOLISM, FLUIDS AND ELECTROLYTES WITHOUT MCC (MDC 10)

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.

Risk Adjustment (CMS-HCC)

Payment categories this diagnosis maps to under CMS-HCC V28, payment year 2026.

  • HCC 277 — Cystic Fibrosis (supersedes HCC 278, HCC 279, HCC 280)

Other models: CMS-HCC V22 HCC 110 · RxHCC V08 HCC 225

Risk scores depend on the enrollee's full accepted diagnosis set and segment; a category mapping alone does not determine payment.

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for E84.9 in the official ICD-10-CM tabular list, quoted as published.

Source: CMS/CDC — ICD-10-CM Tabular ListRelease: FY2027Effective: October 1, 2026

Trace:FY2027 changesChange historyRelease, file and checksum

Notes without a marker are published on E84.9 itself; “inherited from” names the category or block whose note applies here.

Includes

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

  • mucoviscidosis

Source: inherited from E84

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).

Source: inherited from E70-E88

Excludes2 — Not Included Here

Conditions not covered by this code, but which may be reported alongside it when both are present.

Source: inherited from E70-E88

Code Also

Additional codes that may be required to fully describe the encounter.

  • exocrine pancreatic insufficiency (K86.81)

Source: inherited from E84

Coder workflow for E84.9

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

Before you code E84.9

  1. Unspecified does not mean incorrect. When the record gives no greater specificity, E84.9 may be the appropriate code. Check the record for detail that supports a more specific sibling — in this subcategory the siblings differ by the presence or absence of the associated condition. An unspecified code is for records that do not provide the detail a more specific code needs; a query, not an assumption, is the route to specificity (Guidelines I.A.9.b, I.B.18).

    ReviewE84.0, E84.1, E84.8

    See the relationships section · Guide: Other vs unspecified (NEC vs NOS) →

  2. Check the Excludes1 note: if the documentation supports a condition named there, do not simply proceed with E84.9. 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 record document the detail a more specific sibling code needs?
    Yes → Review the specific siblings in this subcategory.
    No → Continue — E84.9 is appropriate when the documentation goes no further.

    ReviewE84.0, E84.1, E84.8

  2. Does the documentation support a condition named in E84.9’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.

    ReviewE34.5, E25.0, D55, Q87.4, E29.1

Consider E84.9. Then review the Code Also note, and 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).
Any detail beyond this code’s title
What the record states that a more specific sibling code would capture — or its absence, which itself supports the unspecified code.

Official instructions as workflow

  • Excludes1 — check before selecting E84.9(5 notes)

    Coding workflow: If the documentation supports a condition named in this note, do not simply proceed with E84.9: the two are not reported together. The one exception is when the record shows the two conditions are unrelated to each other.

    CompareE34.5, E25.0, D55, Q87.4, E29.1

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

  • Excludes2 — not part of E84.9(1 note)

    Coding workflow: The conditions named in this note are not included in E84.9. When the record documents both, both may be reported; the note is a boundary, not a prohibition.

    CompareQ79.6

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

  • Code Also — related condition(1 note)

    Coding workflow: Review the related condition when both are documented and the instruction applies. A Code Also note does not fix sequencing; the order follows the circumstances of the encounter.

    ReviewK86.81

    See the official tabular notes · Guidelines I.A.17

Coding decision scenarios

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

Documentation: The provider documents the condition in the terms of this code’s title and records no further detail.

Coding question: Is a more specific sibling code supportable?

Path: Review the specific siblings in this subcategory and what each requires the record to state.

Reason: A more specific code needs documentation of the distinguishing element; without it the unspecified code is appropriate, and a provider query is the route to specificity (Guidelines I.A.9.b, I.B.18).

ReviewE84.0, E84.1, E84.8

Documentation: Both the condition E84.9 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).

ReviewE34.5, E25.0, D55, Q87.4, E29.1

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.

Don’t confuse E84.9 with…

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

The codes most likely to be picked instead of E84.9 — 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.

  • E34.5— Excludes1 conflict (Excludes1 — generally not reported together)

    Not coded here — the tabular list excludes this pair for the same encounter.

    Not reported together with this code, except where the two conditions are documented as unrelated.

    What moves you there: Documentation of androgen insensitivity syndrome moves the case to E34.5; the two are not reported together unless documented as unrelated.

    Full comparison: E84.9 vs E34.5 →

  • E25.0— Excludes1 conflict (Excludes1 — generally not reported together)

    Not coded here — the tabular list excludes this pair for the same encounter.

    Not reported together with this code, except where the two conditions are documented as unrelated.

    What moves you there: Documentation of congenital adrenal hyperplasia moves the case to E25.0; the two are not reported together unless documented as unrelated.

    Full comparison: E84.9 vs E25.0 →

  • D55— Excludes1 conflict (Excludes1 — generally not reported together)

    Not coded here — the tabular list excludes this pair for the same encounter.

    Not reported together with this code, except where the two conditions are documented as unrelated.

    What moves you there: Documentation of hemolytic anemias attributable to enzyme disorders moves the case to D55; the two are not reported together unless documented as unrelated.

    Full comparison: E84.9 vs D55 →

  • Q87.4— Excludes1 conflict (Excludes1 — generally not reported together)

    Not coded here — the tabular list excludes this pair for the same encounter.

    Not reported together with this code, except where the two conditions are documented as unrelated.

    What moves you there: Documentation of Marfan syndrome moves the case to Q87.4; the two are not reported together unless documented as unrelated.

    Full comparison: E84.9 vs Q87.4 →

  • E29.1— Excludes1 conflict (Excludes1 — generally not reported together)

    Not coded here — the tabular list excludes this pair for the same encounter.

    Not reported together with this code, except where the two conditions are documented as unrelated.

    What moves you there: Documentation of 5-alpha-reductase deficiency moves the case to E29.1; the two are not reported together unless documented as unrelated.

    Full comparison: E84.9 vs E29.1 →

  • Q79.6— Excludes2 relationship (Informational)

    Distinct conditions — both may be reported.

    A distinct condition — both may be reported when both are documented.

    What moves you there: Documentation of Ehlers-Danlos syndromes adds Q79.6; it is not part of this code and both may be reported when both are documented.

    Full comparison: E84.9 vs Q79.6 →

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

Cystic fibrosis, unspecified is a billable ICD-10-CM diagnosis code (E84.9).

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.

Decision Points

The directives on this code's own record, as a pre-claim checklist.

  1. 1 Code Also note — a second code may apply; the guidelines leave its sequencing to the circumstances of the encounter. See the Code Also notes
  2. 5 Excludes1 entries — codes named there are generally not reported together with this code (Guidelines I.A.12.a). See the Excludes1 notes
  3. 1 Excludes2 entry — those conditions are not part of this code and may be reported additionally when documented. See the Excludes2 notes

Checklist rows are derived from this code's own official directives; the wording of each check is MedCoder editorial. The official notes themselves are in the sections each row links to.

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 structured relationships — computed from published CMS and AHRQ datasets

Other codes that name E84.9 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 4 Excludes1 notes across 2 chapters: P59 — Neonatal jaundice from other and unspecified causes (via E84.-), P78 — Other perinatal digestive system disorders, Q45.3 — Other congenital malformations of pancreas and pancreatic duct, Q45.3 — Other congenital malformations of pancreas and pancreatic duct (via E84.-).

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

Referenced by 15 Excludes2 notes across 4 chapters: G11 — Hereditary ataxia (via E84.-), G71 — Primary disorders of muscles (via E84.-), J40 — Bronchitis, not specified as acute or chronic (via E84.-), J40-J4A — Chronic lower respiratory diseases (J40-J4A) (via E84.-), J41 — Simple and mucopurulent chronic bronchitis (via E84.-), J42 — Unspecified chronic bronchitis (via E84.-), J43 — Emphysema (via E84.-), J44 — Other chronic obstructive pulmonary disease (via E84.-), J45 — Asthma (via E84.-), J47 — Bronchiectasis (via E84.-), J4A — Chronic lung allograft dysfunction (via E84.-), J4B — Pulmonary mycetoma (via E84.-), K86 — Other diseases of pancreas (via E84.-), N25.0 — Renal osteodystrophy (via E84.-), N25.81 — Secondary hyperparathyroidism of renal origin (via E84.-).

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

Referenced by 5 Code First instructions across 5 chapters: E08 — Diabetes mellitus due to underlying condition (via E84.-), G63 — Polyneuropathy in diseases classified elsewhere (via E84.-), H42 — Glaucoma in diseases classified elsewhere (via E84.-), J93.12 — Secondary spontaneous pneumothorax (via E84.-), Q55.3 — Atresia of vas deferens (via E84.-).

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.

Referenced by 1 Code Also instruction: Z71.87 — Encounter for pediatric-to-adult transition counseling (via E84.-).

These codes suggest coding this condition alongside when both are present.

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 5 clinically related codes on its CMS exclusion list.

Named in the grouper logic of 2 MS-DRGs: DRG 640 (MDC 10), DRG 641 (MDC 10).

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

Clinical classification (AHRQ CCSR):END012 — Cystic fibrosis (default).

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.

E84.0 — Cystic fibrosis with pulmonary manifestations, E84.11 — Meconium ileus in cystic fibrosis, E84.19 — Cystic fibrosis with other intestinal manifestations, E84.8 — Cystic fibrosis with other manifestations

Same CMS-HCC risk category (V28)

CMS maps these diagnoses to the same Hierarchical Condition Category (Cystic Fibrosis) for risk-adjusted payment.

E84.0 — Cystic fibrosis with pulmonary manifestations, E84.11 — Meconium ileus in cystic fibrosis, E84.19 — Cystic fibrosis with other intestinal manifestations, E84.8 — Cystic fibrosis with other manifestations

Related risk categories

These categories interact through CMS's HCC hierarchy — one can suppress the other's risk-adjustment weight when both are present on a claim.

Lung Transplant Status/Complications, Idiopathic Pulmonary Fibrosis and Lung Involvement in Systemic Sclerosis, Severe Persistent Asthma, Chronic Obstructive Pulmonary Disease, Interstitial Lung Disorders, and Other Chronic Lung Disorders

Same clinical category (CCSR)

AHRQ's Clinical Classifications Software groups these diagnoses under the same clinical category (Cystic fibrosis).

E84.0 — Cystic fibrosis with pulmonary manifestations, E84.11 — Meconium ileus in cystic fibrosis, E84.19 — Cystic fibrosis with other intestinal manifestations, E84.8 — Cystic fibrosis with other manifestations, P09.4 — Abnormal findings on neonatal screening for cystic fibrosis

Same Index main term, other category

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

D58.0 — Hereditary spherocytosis (newborn, spherocytosis), D59.8 — Other acquired hemolytic anemias (acholuric, acquired), D59.9 — Acquired hemolytic anemia, unspecified (hemolytic), D73.89 — Other diseases of spleen (spleen), E03.1 — Congenital hypothyroidism without goiter (newborn, due to or associated with, hypothyroidism, congenital), E27.8 — Other specified disorders of adrenal gland (adrenal), E32.8 — Other diseases of thymus (thymus), E74.21 — Galactosemia (newborn, due to or associated with, galactosemia), E80.4 — Gilbert syndrome (familial nonhemolytic), E80.5 — Crigler-Najjar syndrome (familial nonhemolytic, Crigler-Najjar), G96.198 — Other disorders of meninges, not elsewhere classified (meninges), I31.0 — Chronic adhesive pericarditis (pericardium), I42.3 — Endomyocardial (eosinophilic) disease (endomyocardial), I70.90 — Unspecified atherosclerosis (capillary), I87.8 — Other specified disorders of veins (vein), I89.8 — Other specified noninfective disorders of lymphatic vessels and lymph nodes (lymphatic gland), J60 — Coalworker's pneumoconiosis (lung, with, anthracosis), J61 — Pneumoconiosis due to asbestos and other mineral fibers (lung, with, asbestosis), J62.0 — Pneumoconiosis due to talc dust (lung, diffuse, talc), J62.8 — Pneumoconiosis due to other dust containing silica (lung, silicotic), +83 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.

Alpha-Fetoprotein (AFP) Test

Contextual Map

Every relationship of E84.9 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 E84.9 with these 17 related codes in Claim Check

Hierarchy

Referenced by Excludes1 notes

Referenced by Excludes2 notes (15)

Referenced by Code First instructions

Referenced by Code Also instructions

Clinical classification (CCSR)

Risk adjustment (CMS-HCC)

  • HCC 277 — Cystic Fibrosis [CMS-HCC]: “Cystic Fibrosis — supersedes HCC 278 (Idiopathic Pulmonary Fibrosis and Lung Involvement in Systemic Sclerosis), HCC 279 (Severe Persistent Asthma), HCC 280 (Chronic Obstructive Pulmonary Disease, Interstitial Lung Disorders, and Other Chronic Lung Disorders)”— CMS-HCC V28 · 2026

MS-DRG Grouper

MDC crossing

  • MDC 10 — Endocrine, Nutritional and Metabolic Diseases and Disorders[MDC crossing]: “Endocrine, Nutritional and Metabolic Diseases and Disorders — 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. 5,013 same-MDC procedures group here; browse them on the MDC page.”— CMS MS-DRG Definitions Manual · FY2027

Index entries

  • Disease, diseased, pancreas, fibrocystic[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Fibrocystic, disease, pancreas[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Fibrosis, fibrotic, cystic (of pancreas)[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Jaundice (yellow), newborn, due to or associated with, mucoviscidosis[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Mucoviscidosis[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026

Nearest codes

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 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
Risk adjustment Official source data
2026 Mid-Year Final ICD-10 Mappings + Model Software (cms.gov/files/zip/2026-midyear-final-icd-10-mappings.zip, 2026-midyear-final-model-software.zip) — CMS-HCC V28, PY2026 mid-year final release 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

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. "E84.9 — Cystic fibrosis, unspecified." ICD-10-CM FY2027. https://medcoder.ai/icd10/code/e84.9-cystic-fibrosis-unspecified

Change history

  • FY2016 — October 1, 2015
    In the code set at ICD-10-CM adoption
    Cystic fibrosis, unspecified

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 E84.9 in its code family, with their registry titles.

View all codes in the E84 family