N00.9 ICD-10-CM Code: Acute nephritic syndrome with unspecified morphologic changes

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for N00.9 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 N00.9 itself; “inherited from” names the category or block whose note applies here.

Coder workflow for N00.9

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

Before you code N00.9

1. Unspecified does not mean incorrect. When the record gives no greater specificity, N00.9 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, 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).

   ReviewN00.0, N00.1, N00.2, N00.3, N00.4, N00.5, N00.6, N00.7

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

2. N00.9’s title joins a condition with an associated condition or complication. Confirm each component is documented. Where the classification presumes the link through the “with” convention, only a provider statement that the conditions are unrelated defeats it. A combination code is assigned only when it fully identifies the documented conditions; a required second code for the stage, type or manifestation is still reported when the notes ask for it (Guidelines I.B.9, I.A.15).

   Guide: Combination codes →

3. Check the Excludes1 note: if the documentation supports a condition named there, do not simply proceed with N00.9. 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 — N00.9 is appropriate when the documentation goes no further.

   ReviewN00.0, N00.1, N00.2, N00.3, N00.4, N00.5, N00.6, N00.7

2. Does the documentation support a condition named in N00.9’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.

   ReviewN10, N05, I12

Consider N00.9. 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).

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 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 N00.9(3 notes)

  Coding workflow: If the documentation supports a condition named in this note, do not simply proceed with N00.9: the two are not reported together. The one exception is when the record shows the two conditions are unrelated to each other.

  CompareN10, N05, I12

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

• 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.

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

Coding decision scenarios

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

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.

Indexed Clinical Terms (7)

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.

• Glomerulonephritis, acute
• Glomerulonephritis, poststreptococcal NEC, acute
• Nephritis, nephritic (albuminuric) (azotemic) (congenital) (disseminated) (epithelial) (familial) (focal) (granulomatous) (hemorrhagic) (infantile) (nonsuppurative, excretory) (uremic), acute
• Nephritis, nephritic (albuminuric) (azotemic) (congenital) (disseminated) (epithelial) (familial) (focal) (granulomatous) (hemorrhagic) (infantile) (nonsuppurative, excretory) (uremic), croupous
• Nephritis, nephritic (albuminuric) (azotemic) (congenital) (disseminated) (epithelial) (familial) (focal) (granulomatous) (hemorrhagic) (infantile) (nonsuppurative, excretory) (uremic), poststreptococcal, acute
• Nephritis, nephritic (albuminuric) (azotemic) (congenital) (disseminated) (epithelial) (familial) (focal) (granulomatous) (hemorrhagic) (infantile) (nonsuppurative, excretory) (uremic), war
• Syndrome, nephritic, acute

Don’t confuse N00.9 with…

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

The codes most likely to be picked instead of N00.9 — 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.

• N10— 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 acute tubulo-interstitial nephritis moves the case to N10; the two are not reported together unless documented as unrelated.

  Full comparison: N00.9 vs N10 →

• N05— 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 nephritic syndrome NOS moves the case to N05; the two are not reported together unless documented as unrelated.

  Full comparison: N00.9 vs N05 →

• I12— 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 hypertensive chronic kidney disease moves the case to I12; the two are not reported together unless documented as unrelated.

  Full comparison: N00.9 vs I12 →

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.

Verify Before Coding

• MCC as a secondary diagnosis (FY2026). 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

MS-DRG Grouper Relationships (FY2026)

Potential MS-DRG participation — not a DRG assignment.

FY2026 MS-DRG: MCC — Major 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 286 clinically related codes on its CMS exclusion list.

Named in the grouper logic of 5 MS-DRGs: DRG 698 (MDC 11), DRG 699 (MDC 11), DRG 700 (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):GEN001 — Nephritis; nephrosis; renal sclerosis (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 MCC — 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.

M10.39 — Gout due to renal impairment, multiple sites, N00.0 — Acute nephritic syndrome with minor glomerular abnormality, N00.1 — Acute nephritic syndrome with focal and segmental glomerular lesions, N00.2 — Acute nephritic syndrome with diffuse membranous glomerulonephritis, N00.3 — Acute nephritic syndrome with diffuse mesangial proliferative glomerulonephritis, N00.4 — Acute nephritic syndrome with diffuse endocapillary proliferative glomerulonephritis, N00.5 — Acute nephritic syndrome with diffuse mesangiocapillary glomerulonephritis, N00.6 — Acute nephritic syndrome with dense deposit disease, N00.7 — Acute nephritic syndrome with diffuse crescentic glomerulonephritis, N00.8 — Acute nephritic syndrome with other morphologic changes, N00.A — Acute nephritic syndrome with C3 glomerulonephritis, N00.B1 — Acute nephritic syndrome with idiopathic immune membranoproliferative glomerulonephritis (IC-MPGN), N00.B2 — Acute nephritic syndrome with secondary immune complex membranoproliferative glomerulonephritis (IC-MPGN), N01.0 — Rapidly progressive nephritic syndrome with minor glomerular abnormality, N01.1 — Rapidly progressive nephritic syndrome with focal and segmental glomerular lesions, N01.2 — Rapidly progressive nephritic syndrome with diffuse membranous glomerulonephritis, N01.3 — Rapidly progressive nephritic syndrome with diffuse mesangial proliferative glomerulonephritis, N01.4 — Rapidly progressive nephritic syndrome with diffuse endocapillary proliferative glomerulonephritis, N01.5 — Rapidly progressive nephritic syndrome with diffuse mesangiocapillary glomerulonephritis, N01.6 — Rapidly progressive nephritic syndrome with dense deposit disease, +265 more

Same clinical category (CCSR)

AHRQ's Clinical Classifications Software groups these diagnoses under the same clinical category (Nephritis; nephrosis; renal sclerosis).

M35.0A — Sjögren syndrome with glomerular disease, N00.0 — Acute nephritic syndrome with minor glomerular abnormality, N00.1 — Acute nephritic syndrome with focal and segmental glomerular lesions, N00.2 — Acute nephritic syndrome with diffuse membranous glomerulonephritis, N00.3 — Acute nephritic syndrome with diffuse mesangial proliferative glomerulonephritis, N00.4 — Acute nephritic syndrome with diffuse endocapillary proliferative glomerulonephritis, N00.5 — Acute nephritic syndrome with diffuse mesangiocapillary glomerulonephritis, N00.6 — Acute nephritic syndrome with dense deposit disease, N00.7 — Acute nephritic syndrome with diffuse crescentic glomerulonephritis, N00.8 — Acute nephritic syndrome with other morphologic changes, N00.A — Acute nephritic syndrome with C3 glomerulonephritis, N00.B1 — Acute nephritic syndrome with idiopathic immune membranoproliferative glomerulonephritis (IC-MPGN), N00.B2 — Acute nephritic syndrome with secondary immune complex membranoproliferative glomerulonephritis (IC-MPGN), N01.0 — Rapidly progressive nephritic syndrome with minor glomerular abnormality, N01.1 — Rapidly progressive nephritic syndrome with focal and segmental glomerular lesions, N01.2 — Rapidly progressive nephritic syndrome with diffuse membranous glomerulonephritis, N01.3 — Rapidly progressive nephritic syndrome with diffuse mesangial proliferative glomerulonephritis, N01.4 — Rapidly progressive nephritic syndrome with diffuse endocapillary proliferative glomerulonephritis, N01.5 — Rapidly progressive nephritic syndrome with diffuse mesangiocapillary glomerulonephritis, N01.6 — Rapidly progressive nephritic syndrome with dense deposit disease, +112 more

Same Index main term, other category

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

E75.21 — Fabry (-Anderson) disease (in, Fabrydisease), E78.6 — Lipoprotein deficiency (in, lecithin cholesterol acyltransferase deficiency), E85.4 — Organ-limited amyloidosis (amyloid), I33.0 — Acute and subacute infective endocarditis (in, subacute bacterial endocarditis), M31.0 — Hypersensitivity angiitis (in, Goodpasture's syndrome), M31.19 — Other thrombotic microangiopathy (in, thrombotic thrombocytopenic purpura), M31.31 — Wegener's granulomatosis with renal involvement (in, Wegener's granulomatosis), M31.7 — Microscopic polyangiitis (in, microscopic polyangiitis), M32.14 — Glomerular disease in systemic lupus erythematosus (proliferative NEC, diffuse), M35.04 — Sjögren syndrome with tubulo-interstitial nephropathy (tubulo-interstitial, Sjögren's syndrome), N01.0 — Rapidly progressive nephritic syndrome with minor glomerular abnormality (rapidly progressive, with, minor glomerular abnormality), N01.1 — Rapidly progressive nephritic syndrome with focal and segmental glomerular lesions (rapidly progressive, with, focal and segmental glomerular lesions), N01.2 — Rapidly progressive nephritic syndrome with diffuse membranous glomerulonephritis (rapidly progressive, with, diffuse, membranous glomerulonephritis), N01.3 — Rapidly progressive nephritic syndrome with diffuse mesangial proliferative glomerulonephritis (rapidly progressive, with, diffuse, mesangial proliferative glomerulonephritis), N01.4 — Rapidly progressive nephritic syndrome with diffuse endocapillary proliferative glomerulonephritis (rapidly progressive, with, diffuse, endocapillary proliferative glomerulonephritis), N01.5 — Rapidly progressive nephritic syndrome with diffuse mesangiocapillary glomerulonephritis (rapidly progressive, with, diffuse, mesangiocapillary glomerulonephritis), N01.6 — Rapidly progressive nephritic syndrome with dense deposit disease (rapidly progressive, with, dense deposit disease), N01.7 — Rapidly progressive nephritic syndrome with diffuse crescentic glomerulonephritis (rapidly progressive, with, diffuse, crescentic glomerulonephritis), N01.8 — Rapidly progressive nephritic syndrome with other morphologic changes (rapidly progressive, with, specified morphological changes NEC), N01.9 — Rapidly progressive nephritic syndrome with unspecified morphologic changes (subacute), +59 more

Contextual Map

Every relationship of N00.9 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.

Hierarchy

• N00-N99 — Chapter 14: Diseases of the Genitourinary System (N00-N99) (N00-N99)[Hierarchy]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• N00-N08 — Glomerular diseases[Hierarchy]— CMS ICD-10-CM tabular structure · icd10cm-fy2026

Clinical classification (CCSR)

• GEN001 — Nephritis; nephrosis; renal sclerosis[CCSR]— AHRQ CCSR for ICD-10-CM Diagnoses (HCUP)

MS-DRG Grouper

• MCC — Major Complication or Comorbidity [MS-DRG severity]: “As a secondary diagnosis this code can raise the stay's MS-DRG severity tier (MCC).”— CMS MS-DRG Definitions Manual (Appendix C) · FY2026
• DRG 698 — OTHER KIDNEY AND URINARY TRACT DIAGNOSES WITH MCC[MS-DRG]: “OTHER KIDNEY AND URINARY TRACT DIAGNOSES WITH MCC (MDC 11)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026
• DRG 699 — OTHER KIDNEY AND URINARY TRACT DIAGNOSES WITH CC[MS-DRG]: “OTHER KIDNEY AND URINARY TRACT DIAGNOSES WITH CC (MDC 11)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026
• DRG 700 — OTHER KIDNEY AND URINARY TRACT DIAGNOSES WITHOUT CC/MCC[MS-DRG]: “OTHER KIDNEY AND URINARY TRACT DIAGNOSES WITHOUT CC/MCC (MDC 11)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026
• DRG 791 — PREMATURITY WITH MAJOR PROBLEMS[MS-DRG]: “PREMATURITY WITH MAJOR PROBLEMS (MDC 15)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026
• DRG 793 — FULL TERM NEONATE WITH MAJOR PROBLEMS[MS-DRG]: “FULL TERM NEONATE WITH MAJOR PROBLEMS (MDC 15)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026

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. 3,574 same-MDC procedures group here; browse them on the MDC page.”— CMS MS-DRG Definitions Manual · FY2026
• 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 · FY2026

Index entries

• Glomerulonephritis, acute[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
• Glomerulonephritis, poststreptococcal NEC, acute[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
• Nephritis, nephritic (albuminuric) (azotemic) (congenital) (disseminated) (epithelial) (familial) (focal) (granulomatous) (hemorrhagic) (infantile) (nonsuppurative, excretory) (uremic), acute[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
• Nephritis, nephritic (albuminuric) (azotemic) (congenital) (disseminated) (epithelial) (familial) (focal) (granulomatous) (hemorrhagic) (infantile) (nonsuppurative, excretory) (uremic), croupous[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
• Nephritis, nephritic (albuminuric) (azotemic) (congenital) (disseminated) (epithelial) (familial) (focal) (granulomatous) (hemorrhagic) (infantile) (nonsuppurative, excretory) (uremic), poststreptococcal, acute[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
• Nephritis, nephritic (albuminuric) (azotemic) (congenital) (disseminated) (epithelial) (familial) (focal) (granulomatous) (hemorrhagic) (infantile) (nonsuppurative, excretory) (uremic), war[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026
• Syndrome, nephritic, acute[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026

Nearest codes (14)

• N00 — Acute nephritic syndrome[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• N00.0 — Acute nephritic syndrome with minor glomerular abnormality[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• N00.1 — Acute nephritic syndrome with focal and segmental glomerular lesions[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• N00.2 — Acute nephritic syndrome with diffuse membranous glomerulonephritis[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• N00.3 — Acute nephritic syndrome with diffuse mesangial proliferative glomerulonephritis[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• N00.4 — Acute nephritic syndrome with diffuse endocapillary proliferative glomerulonephritis[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• N00.5 — Acute nephritic syndrome with diffuse mesangiocapillary glomerulonephritis[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• N00.6 — Acute nephritic syndrome with dense deposit disease[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• and 6 more

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

Nearest Codes in This Family

Official ICD-10-CM classifications closest to N00.9 in its code family, with their registry titles.

• N00.3 — Acute nephritic syndrome with diffuse mesangial proliferative glomerulonephritis
• N00.4 — Acute nephritic syndrome with diffuse endocapillary proliferative glomerulonephritis
• N00.5 — Acute nephritic syndrome with diffuse mesangiocapillary glomerulonephritis
• N00.6 — Acute nephritic syndrome with dense deposit disease
• N00.7 — Acute nephritic syndrome with diffuse crescentic glomerulonephritis
• N00.8 — Acute nephritic syndrome with other morphologic changes
• N00.A — Acute nephritic syndrome with C3 glomerulonephritis
• N00.B — Acute nephritic syndrome with immune complex membranoproliferative glomerulonephritis
• N00.B1 — Acute nephritic syndrome with idiopathic immune membranoproliferative glomerulonephritis (IC-MPGN)
• N00.B2 — Acute nephritic syndrome with secondary immune complex membranoproliferative glomerulonephritis (IC-MPGN)

View all codes in the N00 family