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N11.9 ICD-10-CM Code: Chronic tubulo-interstitial nephritis, unspecified

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

Tabular directives
7 inclusion terms · 1 Excludes1 · 1 use-additional code

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.

Use additional codeReport with this code when documented
  • code (B95-B97), to identify infectious agent.
Excludes1Never report with this code
  • pyeloureteritis cystica (N28.85)
IncludesWhat this code covers
  • chronic infectious interstitial nephritis
  • chronic pyelitis
  • chronic pyelonephritis
  • pyelonephritis

+3 more in Instructions

Most relevant related codes MedCoder-derived

Read off the official notes above and this code’s own position in the tabular list. Which to report is a documentation question; Compare shows the two side by side.

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 689 — KIDNEY AND URINARY TRACT INFECTIONS WITH MCC (MDC 11)
  • MS-DRG 690 — KIDNEY AND URINARY TRACT INFECTIONS WITHOUT MCC (MDC 11)
  • MS-DRG 791 — PREMATURITY WITH MAJOR PROBLEMS (MDC 15)
  • MS-DRG 793 — FULL TERM NEONATE WITH MAJOR PROBLEMS (MDC 15)

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 N11.9 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 N11.9 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.

  • chronic infectious interstitial nephritis inherited from N11
  • chronic pyelitis inherited from N11
  • chronic pyelonephritis inherited from N11
  • pyelonephritis inherited from N10-N16

Inclusion Terms

Alternative terms the tabular list files under this code.

  • Chronic interstitial nephritis NOS
  • Chronic pyelitis NOS
  • Chronic pyelonephritis NOS

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 N10-N16

Use Additional Code

Supplementary codes the tabular list directs you to add.

  • Use additional code (B95-B97), to identify infectious agent.

Source: inherited from N11

Coder workflow for N11.9

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

Before you code N11.9

  1. Unspecified does not mean incorrect. When the record gives no greater specificity, N11.9 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. 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).

    ReviewN11.0, N11.1, N11.8

    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 N11.9. 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 — N11.9 is appropriate when the documentation goes no further.

    ReviewN11.0, N11.1, N11.8

  2. Does the documentation support a condition named in N11.9’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.

    ReviewN28.85

Consider N11.9. 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).
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

  • Excludes1 — check before selecting N11.9(1 note)

    Coding workflow: If the documentation supports a condition named in this note, do not simply proceed with N11.9: the two are not reported together. The one exception is when the record shows the two conditions are unrelated to each other.

    CompareN28.85

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

  • Use Additional Code — after identifying N11.9(1 note)

    Coding workflow: Check whether the documentation supports the additional code(s) the note names, and report them with N11.9 when it does. Where the instruction is conditional (“if applicable”, “if known”), it applies only when the record documents the condition.

    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).

ReviewN11.0, N11.1, N11.8

Documentation: Both the condition N11.9 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).

ReviewN28.85

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

Coding question: Is a second code reported with N11.9?

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).

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 N11.9 with…

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

The codes most likely to be picked instead of N11.9 — 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.

  • N28.85— 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 pyeloureteritis cystica moves the case to N28.85; the two are not reported together unless documented as unrelated.

    Full comparison: N11.9 vs N28.85 →

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.

Coding context

Guidelines, coding notes, decision aids, relationships (with MS-DRG and CCSR classification), hierarchy, HCC, coverage and the context map: what a coder reaches for after the core. Each section names whether it is official source data, a MedCoder-derived relationship or MedCoder editorial.

Code Overview

Chronic tubulo-interstitial nephritis, unspecified is a billable ICD-10-CM diagnosis code (N11.9).

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

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 N11.9 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 1 Excludes1 note: N03 — Chronic nephritic syndrome (via N11.-).

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 228 clinically related codes on its CMS exclusion list.

Named in the grouper logic of 4 MS-DRGs: DRG 689 (MDC 11), DRG 690 (MDC 11), DRG 791 (MDC 15), DRG 793 (MDC 15).

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

Clinical classification (AHRQ CCSR):GEN004 — Urinary tract infections (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.

N07.4 — Hereditary nephropathy, not elsewhere classified with diffuse endocapillary proliferative glomerulonephritis, N07.5 — Hereditary nephropathy, not elsewhere classified with diffuse mesangiocapillary glomerulonephritis, N07.6 — Hereditary nephropathy, not elsewhere classified with dense deposit disease, N07.7 — Hereditary nephropathy, not elsewhere classified with diffuse crescentic glomerulonephritis, N07.8 — Hereditary nephropathy, not elsewhere classified with other morphologic lesions, N07.9 — Hereditary nephropathy, not elsewhere classified with unspecified morphologic lesions, N07.B — Hereditary nephropathy, not elsewhere classified with APOL1-mediated kidney disease [AMKD], N10 — Acute pyelonephritis, N11.0 — Nonobstructive reflux-associated chronic pyelonephritis, N11.8 — Other chronic tubulo-interstitial nephritis, N12 — Tubulo-interstitial nephritis, not specified as acute or chronic, N13.0 — Hydronephrosis with ureteropelvic junction obstruction, N13.1 — Hydronephrosis with ureteral stricture, not elsewhere classified, N13.2 — Hydronephrosis with renal and ureteral calculous obstruction, N13.30 — Unspecified hydronephrosis, N13.39 — Other hydronephrosis, N13.6 — Pyonephrosis, N14.0 — Analgesic nephropathy, N14.11 — Contrast-induced nephropathy, N14.19 — Nephropathy induced by other drugs, medicaments and biological substances, +207 more

Same clinical category (CCSR)

AHRQ's Clinical Classifications Software groups these diagnoses under the same clinical category (Urinary tract infections).

A52.75 — Syphilis of kidney and ureter, A54.01 — Gonococcal cystitis and urethritis, unspecified, A56.01 — Chlamydial cystitis and urethritis, A59.03 — Trichomonal cystitis and urethritis, B37.41 — Candidal cystitis and urethritis, B37.49 — Other urogenital candidiasis, N10 — Acute pyelonephritis, N11.0 — Nonobstructive reflux-associated chronic pyelonephritis, N11.1 — Chronic obstructive pyelonephritis, N11.8 — Other chronic tubulo-interstitial nephritis, N12 — Tubulo-interstitial nephritis, not specified as acute or chronic, N13.6 — Pyonephrosis, N15.1 — Renal and perinephric abscess, N30.00 — Acute cystitis without hematuria, N30.01 — Acute cystitis with hematuria, N30.10 — Interstitial cystitis (chronic) without hematuria, N30.11 — Interstitial cystitis (chronic) with hematuria, N30.20 — Other chronic cystitis without hematuria, N30.21 — Other chronic cystitis with hematuria, N30.30 — Trigonitis without hematuria, +40 more

Same Index main term, other category

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

N05.2 — Unspecified nephritic syndrome with diffuse membranous glomerulonephritis (with, diffuse, membranous glomerulonephritis), N05.3 — Unspecified nephritic syndrome with diffuse mesangial proliferative glomerulonephritis (with, diffuse, mesangial proliferative glomerulonephritis), N05.4 — Unspecified nephritic syndrome with diffuse endocapillary proliferative glomerulonephritis (with, diffuse, endocapillary proliferative glomerulonephritis), N05.5 — Unspecified nephritic syndrome with diffuse mesangiocapillary glomerulonephritis (membranoproliferative), N05.6 — Unspecified nephritic syndrome with dense deposit disease (with, dense deposit disease), N05.7 — Unspecified nephritic syndrome with diffuse crescentic glomerulonephritis (with, diffuse, crescentic glomerulonephritis), 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), N10 — Acute pyelonephritis (acute), N12 — Tubulo-interstitial nephritis, not specified as acute or chronic (nonobstructive), N13.6 — Pyonephrosis (with, calculus, with hydronephrosis), N14.3 — Nephropathy induced by heavy metals (lead), N15.0 — Balkan nephropathy (Balkan), N26.9 — Renal sclerosis, unspecified (cirrhotic), N28.84 — Pyelitis cystica (cystica), N28.89 — Other specified disorders of kidney and ureter (salt losing or wasting NEC), O26.83 — Pregnancy related renal disease (complicating pregnancy), O86.21 — Infection of kidney following delivery (puerperal), Q61.19 — Other polycystic kidney, infantile type (polycystic, infantile type NEC), +68 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.

Blood Glucose Test, Gamma-glutamyl Transferase (GGT) Test

Contextual Map

Every relationship of N11.9 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 N11.9 with this related code in Claim Check

Hierarchy

Referenced by Excludes1 notes

  • N03 — Chronic nephritic syndrome[Excludes1](via N11.-): “chronic tubulo-interstitial nephritis (N11.-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2027

Clinical classification (CCSR)

MS-DRG Grouper

MDC crossing

  • 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. 3,578 same-MDC procedures group here; browse them on the MDC page.”— CMS MS-DRG Definitions Manual · FY2027
  • MDC 15 — Newborns and Other Neonates with Conditions Originating in Perinatal Period[MDC crossing]: “Newborns and Other Neonates with Conditions Originating in Perinatal Period — 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

  • Nephritis, nephritic (albuminuric) (azotemic) (congenital) (disseminated) (epithelial) (familial) (focal) (granulomatous) (hemorrhagic) (infantile) (nonsuppurative, excretory) (uremic), tubulo-interstitial (in), chronic (infectious)[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Pyelitis (congenital) (uremic), chronic[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Pyelitis (congenital) (uremic), with, contracted kidney[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Pyelonephritis, chronic[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Pyelonephritis, with, contracted kidney[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2027
  • Pyelonephrosis (obstructive), chronic[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

Reference

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

Indexed Clinical Terms (6)

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.

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. "N11.9 — Chronic tubulo-interstitial nephritis, unspecified." ICD-10-CM FY2027. https://medcoder.ai/icd10/code/n11.9-chronic-tubulo-interstitial-nephritis-unspecified

Change history

  • FY2016 — October 1, 2015
    In the code set at ICD-10-CM adoption
    Chronic tubulo-interstitial nephritis, 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 N11.9 in its code family, with their registry titles.

View all codes in the N11 family