2026 ICD-10-CM Diagnosis Code N10Acute pyelonephritis

ICD-10-CM Codes›N00–N99›N10-N16›N10

ICD-10-CM N10
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

N10 is a billable ICD-10-CM diagnosis code for acute pyelonephritis. It is valid on HIPAA claims for fiscal year 2026 (October 1, 2025 through September 30, 2026) and groups to MS-DRG 689 through 690. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Urinary tract infections.

Code Identity

ICD-10-CM Code
N10
Billable Status
Yes — Valid for Submission
Code Describes
Acute pyelonephritis
Chapter
N10-N16
Renal tubulo-interstitial diseases

Code Classification

ChapterN00–N99Diseases of the genitourinary system
SectionN10-N16Renal tubulo-interstitial diseases
CategoryN10Acute pyelonephritis
This CodeN10Acute pyelonephritis

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Acute bacterial tubulointerstitial nephritis
  • Acute fungal tubulointerstitial nephritis
  • Acute infectious tubulointerstitial nephritis
  • Acute nephritis due to another disorder
  • Acute on chronic tubulointerstitial nephritis
  • Acute pyelitis
  • Acute pyelitis with renal medullary necrosis
  • Acute pyelitis without renal medullary necrosis
  • Acute pyelonephritis
  • Acute pyelonephritis caused by bacterium
  • Acute pyelonephritis with medullary necrosis
  • Acute pyelonephritis without medullary necrosis
  • Acute tubulointerstitial nephritis
  • Acute tubulointerstitial nephritis associated with systemic infection
  • Acute tubulo-interstitial nephritis due to immunological disorder
  • Acute viral tubulointerstitial nephritis
  • Bacterial nephritis
  • Emphysematous pyelitis
  • Emphysematous pyelonephritis
  • Focal pyelonephritis
  • Fungal infection of kidney
  • Idiopathic acute tubulointerstitial nephritis
  • Pyelitis
  • Pyelonephritis associated with another disorder
  • Renal ocular syndrome
  • Viral kidney infection

Tabular List NotesGuidance

Coding notes and annotation back-references applicable to this code.

Inclusion Terms

  • Acute infectious interstitial nephritis
  • Acute pyelitis
  • Acute tubulo-interstitial nephritis
  • Hemoglobin nephrosis
  • Myoglobin nephrosis

Use Additional Code

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.

    • Nephritis, nephritic(albuminuric) (azotemic) (congenital) (disseminated) (epithelial) (familial) (focal) (granulomatous) (hemorrhagic) (infantile) (nonsuppurative, excretory) (uremic)
      • tubulo-interstitial (in)
        • acute (infectious)
    • Nephrosis, nephrotic(Epstein's) (syndrome) (congenital)
      • hemoglobin
    • Nephrosis, nephrotic(Epstein's) (syndrome) (congenital)
      • myoglobin
    • Pyelitis(congenital) (uremic)
      • acute
    • Pyelonephritis
      • acute

Clinical ClassificationClinical

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

CCSR GEN004
Urinary tract infections
Default principal diagnosis: inpatient Yes · outpatient Yes

Clinical InformationClinical

  • Emphysematous Pyelonephritis

    acute often necrotizing pyelonephritis characterized by accumulation of gas within and around renal parenchyma. emphysematous pyelonephritis is typically associated with bacterial infection in diabetes mellitus and immunocompromised patient.

  • Pyelitis

    inflammation of the kidney pelvis and kidney calices where urine is collected before discharge, but does not involve the renal parenchyma (the nephrons) where urine is processed.

  • Acute Pyelonephritis

    sudden onset pyelonephritis.

  • Pyelitis

    inflammation of the renal pelvis.

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 N10 to ICD-9-CMHistory

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

ICD-9-CM
590.10 Ac pyelonephritis NOS
Approximate The match is approximate rather than exact.
ICD-9-CM
590.11 Ac pyelonephr w med necr
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 N10Overview

Is N10 (Acute pyelonephritis) a billable code?

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

What MS-DRG does N10 group to?

When acute pyelonephritis is the principal diagnosis on an inpatient stay, it groups to MS-DRG 689, 690, with relative weights from 0.8095 to 1.1603 depending on complications. Higher weights mean higher Medicare reimbursement.

What is the ICD-9 equivalent of N10?

Under the General Equivalence Mappings, acute pyelonephritis converts to ICD-9-CM 590.10 (ac pyelonephritis NOS) and 590.11 (ac pyelonephr w med necr). 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.