2026 ICD-10-CM Diagnosis Code N00.9Acute nephritic syndrome with unspecified morphologic changes

ICD-10-CM Codes›N00–N99›N00-N08›N00

ICD-10-CM N00.9
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

N00.9 is a billable ICD-10-CM diagnosis code for acute nephritic syndrome with unspecified morphologic changes. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 698 through 700. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Nephritis; nephrosis; renal sclerosis.

Code Identity

ICD-10-CM Code
N00.9
Billable Status
Yes — Valid for Submission
Code Describes
Acute nephritic syndrome with unspecified morphologic changes
Short Description
Acute nephritic syndrome with unsp morphologic changes
Parent Code
N00
Acute nephritic syndrome

Code Classification

ChapterN00–N99Diseases of the genitourinary system
SectionN00-N08Glomerular diseases
CategoryN00Acute nephritic syndrome
This CodeN00.9Acute nephritic syndrome with unspecified morphologic changes

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Acute diffuse nephritis
  • Acute exudative glomerulonephritis
  • Acute exudative nephritis
  • Acute focal nephritis
  • Acute glomerulonephritis
  • Acute glomerulonephritis associated with another disorder
  • Acute nephritis
  • Acute nephritis due to another disorder
  • Acute post-streptococcal glomerulonephritis
  • Acute radiation nephritis
  • Anaphylactoid glomerulonephritis
  • Exudative glomerulonephritis
  • Exudative nephritis
  • Glomerular disease due to infectious disease
  • Post-infectious glomerulonephritis
  • Radiation nephritis

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

External Cause of Injuries IndexGuidance

References for this code in the External Cause of Injuries Index.

    • 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

Clinical ClassificationClinical

AHRQ’s CCSR groups this code into broader clinical categories.

CCSR GEN001
Nephritis; nephrosis; renal sclerosis
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Exudative Glomerulonephritis

    inflammation of the glomeruli with infiltration by polymorphonuclear leukocytes.

  • Acute Glomerulonephritis

    an acute inflammation of the glomeruli, generally secondary to infection or injury.

  • Subacute Glomerulonephritis

    a term that refers to glomerular damage resulting in hematuria, proteinuria, and azotemia. the histopathologic changes include rapidly progressive glomerulonephritis and membranoproliferative glomerulonephritis.

Patient EducationClinical

Kidney Diseases

You have two kidneys, each about the size of your fist. They are near the middle of your back, just below the rib cage. Inside each kidney there are about a million tiny structures called nephrons. They filter your blood. They remove wastes and extra water, which become urine. The urine flows through tubes called ureters.

Read the full article at MedlinePlus

Courtesy of MedlinePlus, a service of the U.S. National Library of Medicine.

Convert N00.9 to ICD-9-CMHistory

The closest ICD-9-CM equivalents under the General Equivalence Mappings.

ICD-9-CM
580.9 Acute nephritis NOS
Approximate The match is approximate rather than exact.

Code HistoryHistory

FY 2016AddedAdded to the ICD-10-CM code setEffective October 1, 2015, the first year of ICD-10-CM.
FY 2017–2025No changes
FY 2026CurrentCurrent code set, no changesEffective October 1, 2025 through September 30, 2026.

Questions About N00.9Overview

Is N00.9 (Acute nephritic syndrome) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report acute nephritic syndrome with unspecified morphologic changes on HIPAA-covered claims from October 1, 2025 through September 30, 2026.

What MS-DRG does N00.9 group to?

When acute nephritic syndrome with unspecified morphologic changes is the principal diagnosis on an inpatient stay, it groups to MS-DRG 698, 699, 700, with relative weights from 0.6899 to 1.6544 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of N00.9?

Under the General Equivalence Mappings, acute nephritic syndrome with unspecified morphologic changes converts to ICD-9-CM 580.9 (acute nephritis NOS). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Not chronic - A diagnosis code that does not fit the criteria for chronic condition (duration, ongoing medical treatment, and limitations) is considered not chronic. Some codes designated as not chronic are acute conditions. Other diagnosis codes that indicate a possible chronic condition, but for which the duration of the illness is not specified in the code description (i.e., we do not know the condition has lasted 12 months or longer) also are considered not chronic.