2026 ICD-10-CM Diagnosis Code N05.5Unspecified nephritic syndrome with diffuse mesangiocapillary glomerulonephritis

ICD-10-CM Codes›N00–N99›N00-N08›N05

ICD-10-CM N05.5
CMSSource: CMS FY 2026 ICD-10-CM dataset · Effective Oct 1, 2025 – Sep 30, 2026

N05.5 is a billable ICD-10-CM diagnosis code for unspecified nephritic syndrome with diffuse mesangiocapillary glomerulonephritis. 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. Coders also document this condition as C4 glomerulopathy. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Nephritis; nephrosis; renal sclerosis.

Code Identity

ICD-10-CM Code
N05.5
Billable Status
Yes — Valid for Submission
Code Describes
Unspecified nephritic syndrome with diffuse mesangiocapillary glomerulonephritis
Short Description
Unsp nephritic syndrome w diffuse mesangiocap glomrlneph
Parent Code
N05
Unspecified nephritic syndrome

Code Classification

ChapterN00–N99Diseases of the genitourinary system
SectionN00-N08Glomerular diseases
CategoryN05Unspecified nephritic syndrome
This CodeN05.5Unspecified nephritic syndrome with diffuse mesangiocapillary glomerulonephritis

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • C4 glomerulopathy
  • Complement component 4 glomerulonephritis
  • Mesangiocapillary glomerulonephritis
  • Mesangiocapillary glomerulonephritis type III
  • Mesangiocapillary glomerulonephritis type IV
  • Mesangiocapillary glomerulonephritis, type I
  • Nephritic syndrome
  • Nephritic syndrome co-occurrent and due to membranoproliferative glomerulonephritis type III

Tabular List NotesGuidance

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

Inclusion Terms

  • Unspecified nephritic syndrome with membranoproliferative glomerulonephritis, types 1 and 3, or NOS

Type 1 Excludes

  • Unspecified nephritic syndrome with C3 glomerulonephritis N05.A
  • Unspecified nephritic syndrome with C3 glomerulopathy N05.A

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
      • diffuse
        • mesangiocapillary
    • Glomerulonephritis
      • membranoproliferative (diffuse) (type 1 or 3)
    • Glomerulonephritis
      • mesangiocapillary (diffuse) NEC
    • Nephritis, nephritic(albuminuric) (azotemic) (congenital) (disseminated) (epithelial) (familial) (focal) (granulomatous) (hemorrhagic) (infantile) (nonsuppurative, excretory) (uremic)
      • with
        • diffuse
          • mesangiocapillary glomerulonephritis
    • Nephritis, nephritic(albuminuric) (azotemic) (congenital) (disseminated) (epithelial) (familial) (focal) (granulomatous) (hemorrhagic) (infantile) (nonsuppurative, excretory) (uremic)
      • membranoproliferative (diffuse) (type 1 or 3)

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

  • Nephritic Syndrome

    a syndrome characterized by hematuria with dysmorphic red blood cells, red blood cell casts, and proteinuria; systemic manifestations may be present, including hypertension, edema, oliguria.

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 N05.5 to ICD-9-CMHistory

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

ICD-9-CM
583.2 Membranoprolif nephr 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 N05.5Overview

Is N05.5 (Unspecified nephritic syndrome) a billable code?

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

What MS-DRG does N05.5 group to?

When unspecified nephritic syndrome with diffuse mesangiocapillary glomerulonephritis 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 N05.5?

Under the General Equivalence Mappings, unspecified nephritic syndrome with diffuse mesangiocapillary glomerulonephritis converts to ICD-9-CM 583.2 (membranoprolif nephr NOS). 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.