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N18.9 ICD-10-CM Code: Chronic kidney disease, unspecified

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

Coding at a Glance

Tabular directives
5 inclusion terms · 11 Excludes2 · 3 use-additional codes · 3 code-first instructions

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 008 — SIMULTANEOUS PANCREAS AND KIDNEY TRANSPLANT (MDC PRE)
  • MS-DRG 019 — SIMULTANEOUS PANCREAS AND KIDNEY TRANSPLANT WITH HEMODIALYSIS (MDC PRE)
  • MS-DRG 682 — RENAL FAILURE WITH MCC (MDC 11)
  • MS-DRG 683 — RENAL FAILURE WITH CC (MDC 11)
  • MS-DRG 684 — RENAL FAILURE WITHOUT CC/MCC (MDC 11)

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 N18.9 in the official ICD-10-CM tabular list, quoted as published.

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

Notes without a marker are published on N18.9 itself; “inherited from” names the category or block whose note applies here.

Inclusion Terms

Alternative terms the tabular list files under this code.

  • Chronic renal disease
  • Chronic renal failure NOS
  • Chronic renal insufficiency
  • Chronic uremia NOS
  • Diffuse sclerosing glomerulonephritis NOS

Excludes2 — Not Included Here

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

Source: inherited from N17-N19

Code First

Underlying conditions that must be sequenced before this code.

Source: inherited from N18

Use Additional Code

Supplementary codes the tabular list directs you to add.

  • Use additional code, if applicable, to identify:
  • associated cachexia (E88.A)
  • kidney transplant status (Z94.0)

Source: inherited from N18

Coder workflow for N18.9

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

Before you code N18.9

  1. Unspecified does not mean incorrect. When the record gives no greater specificity, N18.9 may be the appropriate code. Check the record for detail that supports a more specific sibling — in this subcategory the siblings differ by acute versus chronic, severity, stage. 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).

    ReviewN18.1, N18.2, N18.3, N18.4, N18.5, N18.6

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

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 — N18.9 is appropriate when the documentation goes no further.

    ReviewN18.1, N18.2, N18.3, N18.4, N18.5, N18.6

  2. Is the underlying (etiologic) condition the Code First note names documented?
    Yes → Sequence the underlying condition first, then N18.9.
    No → Continue; do not add an underlying condition the record does not document.

    ReviewE08.22, E09.22, E10.22, E11.22, E13.22, I12

Consider N18.9. Then work the Use Additional Code 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).
Acuity
Acute or chronic as documented; when both are documented and separate codes exist, both are reported with the acute code first (Guidelines I.B.8).
Severity
Mild, moderate or severe as the provider states it; severity is not inferred from the clinical picture.
Stage
The documented stage decides the sibling code; where a Use Additional Code note asks for a stage code, report it as well.
The underlying (etiologic) condition
Named in the Code First note; sequenced before this code when documented (Guidelines I.A.13).
The conditions the Use Additional Code note names
Reported with this code when documented; a conditional instruction (“if applicable”, “if known”) applies only when the record supports it.
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

  • Excludes2 — not part of N18.9(11 notes)

    Coding workflow: The conditions named in this note are not included in N18.9. When the record documents both, both may be reported; the note is a boundary, not a prohibition.

    CompareP96.0, N14, R39.2, D59.3, K76.7, O90.41

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

  • Code First — sequencing check(3 notes)

    Coding workflow: Check whether the underlying or etiologic condition the note names is documented. When it is, sequence it before N18.9. Do not add an underlying condition the record does not document.

    ReviewE08.22, E09.22, E10.22, E11.22, E13.22, I12

    See the official tabular notes · Guidelines I.A.13

  • Use Additional Code — after identifying N18.9(3 notes)

    Coding workflow: Check whether the documentation supports the additional code(s) the note names, and report them with N18.9 when it does. Where the instruction is conditional (“if applicable”, “if known”), it applies only when the record documents the condition.

    ReviewE88.A, Z94.0

    See the official tabular notes · Guidelines I.A.13

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).

ReviewN18.1, N18.2, N18.3, N18.4, N18.5, N18.6

Documentation: The underlying condition the Code First note names is documented alongside this condition.

Coding question: How are the two sequenced?

Path: Review the Code First note.

Reason: The underlying condition is sequenced first and the manifestation follows (Guidelines I.A.13).

ReviewE08.22, E09.22, E10.22, E11.22, E13.22, I12

Documentation: A condition the Use Additional Code note names is documented.

Coding question: Is a second code reported with N18.9?

Path: Review the Use Additional Code note and the code it names.

Reason: The additional code is reported when the record documents the condition; a conditional instruction applies only when its condition is met (Guidelines I.A.13).

ReviewE88.A, Z94.0

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

Chronic kidney disease, unspecified is a billable ICD-10-CM diagnosis code (N18.9).

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 (17)

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.

Official Coding Guidelines

Official source data — quoted verbatim from the CMS/NCHS Official Guidelines

Official source data — quoted verbatim from the CMS/NCHS Official Guidelines

Verbatim excerpts from the ICD-10-CM Official Guidelines for Coding and Reporting (CMS/NCHS) that govern this code.

Chapter 9: Diseases of the Circulatory System (I00 -I99)

2) Hypertensive Chronic Kidney Disease Assign codes from category I12, Hypertensive chronic kidney disease, when both hypertension and a condition classifiable to category N18, Chronic kidney disease (CKD), are present. CKD should not be coded as hypertensive if the provider indicates the CKD is not related to the hypertension.

Chapter 9: Diseases of the Circulatory System (I00 -I99)

The appropriate code from category N18 should be used as a secondary code with a code from category I12 to identify the stage of chronic kidney disease.

Chapter 9: Diseases of the Circulatory System (I00 -I99)

The ap propriate code from category N18, Chronic kidney disease, should be used as a secondary code with a code from category I13 to identify the stage of chronic kidney disease.

Chapter 14: Diseases of Genitourinary System (N00-N99)

2) Chronic kidney disease and kidney transplant status Patients who have undergone kidney transplant may still have some form of chronic kidney disease (CKD) because the kidney transplant may not fully restore kidney function. Therefore, the presence of CKD alone does not constitute a transplant complication. Assign the appropriate N18 code for the patient’s stage of CKD and code Z94.0, Kidney transplant status. If a transplant complication such as failure or rejection or other transplant complication is documented, see section I.C.19.g for information on coding complications of a kidney transplant. If the documentation is unclear as to whether the patient has a complication of the transplant, query the provider.

Decision Points

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

  1. Sequencing: 3 Code First instructions — the underlying condition is sequenced before this code when present. See the Code First notes
  2. 3 Use Additional Code instructions — report the named additional code(s) when the documentation supports them. See the Use Additional Code notes
  3. 11 Excludes2 entries — 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

  • 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 N18.9 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 3 Excludes1 notes: N19 — Unspecified kidney failure, N19 — Unspecified kidney failure (via N18.-), N28.9 — Disorder of kidney and ureter, unspecified.

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

Referenced by 2 Code First instructions across 2 chapters: D63.1 — Anemia in chronic kidney disease (via N18.-), I5A — Non-ischemic myocardial injury (non-traumatic) (via N18.-).

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 4 Use Additional Code instructions: I12.9 — Hypertensive chronic kidney disease with stage 1 through stage 4 chronic kidney disease, or unspecified chronic kidney disease, I13.0 — Hypertensive heart and chronic kidney disease with heart failure and stage 1 through stage 4 chronic kidney disease, or unspecified chronic kidney disease, I13.10 — Hypertensive heart and chronic kidney disease without heart failure, with stage 1 through stage 4 chronic kidney disease, or unspecified chronic kidney disease, I75.81 — Atheroembolism of kidney (via N18.-).

These codes instruct coders to additionally report this code when it applies.

Referenced by 12 Code Also instructions across 3 chapters: D59.3 — Hemolytic-uremic syndrome (via N18.-), E20.810 — Autosomal dominant hypocalcemia (via N18.-), N00 — Acute nephritic syndrome (via N18.-), N00-N08 — Glomerular diseases (N00-N08) (via N18.-), N01 — Rapidly progressive nephritic syndrome (via N18.-), N02 — Recurrent and persistent hematuria (via N18.-), N03 — Chronic nephritic syndrome (via N18.-), N04 — Nephrotic syndrome (via N18.-), N05 — Unspecified nephritic syndrome (via N18.-), N06 — Isolated proteinuria with specified morphological lesion (via N18.-), N07 — Hereditary nephropathy, not elsewhere classified (via N18.-), N08 — Glomerular disorders in diseases classified elsewhere (via N18.-).

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

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 5 MS-DRGs: DRG 008 (MDC PRE), DRG 019 (MDC PRE), DRG 682 (MDC 11), DRG 683 (MDC 11), DRG 684 (MDC 11).

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

Clinical classification (AHRQ CCSR):GEN003 — Chronic kidney disease (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 category (CCSR)

AHRQ's Clinical Classifications Software groups these diagnoses under the same clinical category (Chronic kidney disease).

I12.0 — Hypertensive chronic kidney disease with stage 5 chronic kidney disease or end stage renal disease, I12.9 — Hypertensive chronic kidney disease with stage 1 through stage 4 chronic kidney disease, or unspecified chronic kidney disease, I13.0 — Hypertensive heart and chronic kidney disease with heart failure and stage 1 through stage 4 chronic kidney disease, or unspecified chronic kidney disease, I13.10 — Hypertensive heart and chronic kidney disease without heart failure, with stage 1 through stage 4 chronic kidney disease, or unspecified chronic kidney disease, I13.11 — Hypertensive heart and chronic kidney disease without heart failure, with stage 5 chronic kidney disease, or end stage renal disease, I13.2 — Hypertensive heart and chronic kidney disease with heart failure and with stage 5 chronic kidney disease, or end stage renal disease, N18.1 — Chronic kidney disease, stage 1, N18.2 — Chronic kidney disease, stage 2 (mild), N18.3 — Chronic kidney disease, stage 3 (moderate), N18.30 — Chronic kidney disease, stage 3 unspecified, N18.31 — Chronic kidney disease, stage 3a, N18.32 — Chronic kidney disease, stage 3b, N18.4 — Chronic kidney disease, stage 4 (severe), N18.5 — Chronic kidney disease, stage 5, N18.6 — End stage renal disease, R88.0 — Cloudy (hemodialysis) (peritoneal) dialysis effluent, Z49.01 — Encounter for fitting and adjustment of extracorporeal dialysis catheter, Z49.02 — Encounter for fitting and adjustment of peritoneal dialysis catheter, Z49.31 — Encounter for adequacy testing for hemodialysis, Z49.32 — Encounter for adequacy testing for peritoneal dialysis, +6 more

Same Index main term, other category

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

N05.6 — Unspecified nephritic syndrome with dense deposit disease (dense deposit), N05.7 — Unspecified nephritic syndrome with diffuse crescentic glomerulonephritis (crescentic NEC), N05.8 — Unspecified nephritic syndrome with other morphologic changes (proliferative NEC), N05.9 — Unspecified nephritic syndrome with unspecified morphologic changes, N05.A — Unspecified nephritic syndrome with C3 glomerulonephritis (with, C3, glomerulopathy), N17.0 — Acute kidney failure with tubular necrosis (renal, with, tubular necrosis), N17.1 — Acute kidney failure with acute cortical necrosis (renal, acute, with, cortical necrosis), N17.2 — Acute kidney failure with medullary necrosis (renal, acute, with, medullary necrosis), N17.8 — Other acute kidney failure (renal, acute, specified NEC), N17.9 — Acute kidney failure, unspecified (renal, acute), N19 — Unspecified kidney failure, N28.9 — Disorder of kidney and ureter, unspecified (renal), N31.0 — Uninhibited neuropathic bladder, not elsewhere classified (bladder, uninhibited), N31.1 — Reflex neuropathic bladder, not elsewhere classified (bladder, reflex), N31.2 — Flaccid neuropathic bladder, not elsewhere classified (bladder), N31.9 — Neuromuscular dysfunction of bladder, unspecified (bladder), N52.9 — Male erectile dysfunction, unspecified (erection), N91.0 — Primary amenorrhea (menstruation at puberty), N97.0 — Female infertility associated with anovulation (ovulation causing infertility), N99.0 — Postprocedural (acute) (chronic) kidney failure (renal, postprocedural), +427 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.

Iron Panel, Lipid Panel, Partial Thromboplastin Time (PTT) Test, Prothrombin Time Test and INR (PT/INR)

Contextual Map

Every relationship of N18.9 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 N18.9 with these 16 related codes in Claim Check

Hierarchy

Index manifestation

Referenced by Excludes1 notes

Referenced by Code First instructions

Referenced by Use Additional Code instructions

Referenced by Code Also instructions (12)

Clinical classification (CCSR)

MS-DRG Grouper

MDC crossing

  • Pre-MDC[MDC crossing]: “Pre-MDC — 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. 153 same-MDC procedures group here; browse them on the MDC page.”— CMS MS-DRG Definitions Manual · FY2026
  • MDC 11 — Diseases and Disorders of the Kidney and Urinary Tract[MDC crossing]: “Diseases and Disorders of the Kidney and Urinary Tract — 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. 3,574 same-MDC procedures group here; browse them on the MDC page.”— CMS MS-DRG Definitions Manual · FY2026

Index entries (17)

  • Apoplexia, apoplexy, apoplectic, uremic[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Disease, diseased, kidney (functional) (pelvis), chronic[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Disease, diseased, renal (functional) (pelvis), chronic[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Failure, failed, renal, chronic[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Glomerulonephritis, diffuse, sclerosing[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Glomerulonephritis, sclerosing, diffuse[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Insufficiency, insufficient, kidney, chronic[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • Insufficiency, insufficient, renal (acute), chronic[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
  • and 9 more

Nearest codes (10)

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
Coding guidelines Official source data
ICD-10-CM Official Guidelines for Coding and Reporting (FY2026), quoted by section 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

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. "N18.9 — Chronic kidney disease, unspecified." ICD-10-CM FY2026. https://medcoder.ai/icd10/code/n18.9-chronic-kidney-disease-unspecified

Change history

  • FY2016 — October 1, 2015
    In the code set at ICD-10-CM adoption
    Chronic kidney disease, unspecified

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.

Nearest Codes in This Family

Official ICD-10-CM classifications closest to N18.9 in its code family, with their registry titles.

View all codes in the N18 family