2026 ICD-10-CM Diagnosis Code N11.8Other chronic tubulo-interstitial nephritis

ICD-10-CM Codes›N00–N99›N10-N16›N11

ICD-10-CM N11.8
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

N11.8 is a billable ICD-10-CM diagnosis code for other chronic tubulo-interstitial nephritis. 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. Coders also document this condition as chronic infective interstitial nephritis. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Urinary tract infections.

Code Identity

ICD-10-CM Code
N11.8
Billable Status
Yes — Valid for Submission
Code Describes
Other chronic tubulo-interstitial nephritis
Short Description
Other chronic tubulo-interstitial nephritis
Same as the full description in the CMS dataset.
Parent Code
N11
Chronic tubulo-interstitial nephritis

Code Classification

ChapterN00–N99Diseases of the genitourinary system
SectionN10-N16Renal tubulo-interstitial diseases
CategoryN11Chronic tubulo-interstitial nephritis
This CodeN11.8Other chronic tubulo-interstitial nephritis

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Chronic infective interstitial nephritis
  • Chronic pyelonephritis
  • Chronic urinary tract infection
  • Karyomegalic interstitial nephritis
  • Pyelitis
  • Pyelitis glandularis
  • Renal interstitial fibrosis
  • Xanthogranulomatous pyelonephritis

Tabular List NotesGuidance

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

Inclusion Terms

  • Nonobstructive chronic pyelonephritis NOS

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)
        • chronic (infectious)
          • nonobstructive
    • Nephritis, nephritic(albuminuric) (azotemic) (congenital) (disseminated) (epithelial) (familial) (focal) (granulomatous) (hemorrhagic) (infantile) (nonsuppurative, excretory) (uremic)
      • tubulo-interstitial (in)
        • chronic (infectious)
          • specified NEC
    • Pyelonephritis
      • chronic
        • nonobstructive
    • Pyelonephritis
      • chronic
        • specified NEC
    • Pyelonephritis
      • nonobstructive
        • chronic

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

  • 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.

  • Pyelitis

    inflammation of the renal pelvis.

  • Xanthogranulomatous Pyelonephritis

    chronic, destructive infection of the kidney characterized by lipid-laden macrophages in the setting of obstruction secondary to infected renal stones, most commonly caused by proteus or escherichia coli.

  • Chronic Pyelonephritis

    persistent pyelonephritis.

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 N11.8 to ICD-9-CMHistory

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

ICD-9-CM
590.01 Chr pyeloneph 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 N11.8Overview

Is N11.8 (Chronic tubulo-interstitial nephritis) a billable code?

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

What MS-DRG does N11.8 group to?

When other chronic tubulo-interstitial nephritis 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 N11.8?

Under the General Equivalence Mappings, other chronic tubulo-interstitial nephritis converts to ICD-9-CM 590.01 (chr pyeloneph w med necr). The mapping is approximate, so confirm the match fits the documentation.

Footnotes

[1] Chronic - a chronic condition code indicates a condition lasting 12 months or longer and its effect on the patient based on one or both of the following criteria:

  • The condition results in the need for ongoing intervention with medical products,treatment, services, and special equipment
  • The condition places limitations on self-care, independent living, and social interactions.