2027 ICD-10-CM Diagnosis Code N01.1Rapidly progressive nephritic syndrome with focal and segmental glomerular lesions

ICD-10-CM Codes›N00–N99›N00-N08›N01

ICD-10-CM N01.1
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

N01.1 is a billable ICD-10-CM diagnosis code for rapidly progressive nephritic syndrome with focal and segmental glomerular lesions. It is valid on HIPAA claims for fiscal year 2027 (October 1, 2026 through September 30, 2027) and groups to MS-DRG 698 through 700, 791, 793. As a secondary diagnosis, it counts as a major complication or comorbidity (MCC) and places an inpatient stay in the highest severity level of its MS-DRG family. It does not count, however, when the principal diagnosis is one of 286 closely related codes. Coders also document this condition as rapidly progressive nephritic syndrome. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Nephritis; nephrosis; renal sclerosis.

N01.1 does not risk-adjust for Medicare Advantage under the CMS-HCC V28 model. It still risk-adjusts in the ESRD (V21) category 141 for payment year 2027.

Code Identity

ICD-10-CM Code
N01.1
Billable Status
Yes — Valid for Submission
Code Describes
Rapidly progressive nephritic syndrome with focal and segmental glomerular lesions
Short Description
Rapidly progr neph synd w focal and seg glomerular lesions
Parent Code
N01
Rapidly progressive nephritic syndrome

Code Classification

ChapterN00–N99Diseases of the genitourinary system
SectionN00-N08Glomerular diseases
CategoryN01Rapidly progressive nephritic syndrome
This CodeN01.1Rapidly progressive nephritic syndrome with focal and segmental glomerular lesions

Medicare Risk Adjustment (HCC)Billing

N01.1 does not risk-adjust for Medicare Advantage under the CMS-HCC V28 model, but it maps to payment categories in the other CMS models shown below.

CMS-HCC V28 (Medicare Advantage Payment Model)
Not mapped
no payment category in the model that pays 100% of MA risk scores
Prior Model (CMS-HCC V24)
Not mapped under V24
this diagnosis newly risk-adjusts under the V28 model
Other CMS Models
ESRD (V21): HCC 141
ESRD V21 weights: 0.000 dialysis, 0.000 functioning graft
Part D (RxHCC)
Not mapped
N01.1 does not risk-adjust in the RxHCC prescription drug model

Source: CMS Payment Year 2027 risk adjustment mappings and model software. Weights are relative factors, not dollar amounts; a beneficiary's total RAF also includes demographics and interactions. Browse all CMS-HCC categories.

Approximate SynonymsGuidance

Alternate terms and clinical phrases that map to this code.

  • Rapidly progressive nephritic syndrome
  • Rapidly progressive nephritic syndrome, focal and segmental glomerular lesions

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to N01.1: its own notes plus those printed at N01, block N00-N08, and Chapter 14. A note printed at a category, block or chapter applies to every code under it.

Includes

Further defines, or gives examples of, the content of the category.

From N01 Rapidly progressive nephritic syndrome applies to 11 codes
  • rapidly progressive glomerular disease
  • rapidly progressive glomerulonephritis
  • rapidly progressive nephritis

Applicable To

Conditions this code is used for: synonyms of the title or, for "other specified" codes, the conditions assigned to it. The list is not exhaustive.

  • Rapidly progressive nephritic syndrome with focal and segmental hyalinosis
  • Rapidly progressive nephritic syndrome with focal and segmental sclerosis
  • Rapidly progressive nephritic syndrome with focal glomerulonephritis

Excludes1

Not coded here: the excluded code is never reported together with this one, unless the two conditions are unrelated.

From N01 Rapidly progressive nephritic syndrome applies to 11 codes
  • nephritic syndrome NOS (N05.-)
From Block N00-N08 Glomerular diseases applies to 107 codes
  • hypertensive chronic kidney disease (I12.-)

Excludes2

Not included here: the excluded condition is not part of this code, but a patient may have both, so both codes may be reported.

From Chapter 14 (N00-N99) Diseases of the genitourinary system applies to 838 codes
  • certain conditions originating in the perinatal period (P04-P96)
  • certain infectious and parasitic diseases (A00-B99)
  • complications of pregnancy, childbirth and the puerperium (O00-O9A)
  • congenital malformations, deformations and chromosomal abnormalities (Q00-Q99)
  • endocrine, nutritional and metabolic diseases (E00-E88)
  • injury, poisoning and certain other consequences of external causes (S00-T88)
  • neoplasms (C00-D49)
  • symptoms, signs and abnormal clinical and laboratory findings, not elsewhere classified (R00-R94)

Code Also

A second code may be needed to fully describe the condition; the note gives no sequencing direction.

From Block N00-N08 Glomerular diseases applies to 107 codes
  • any associated kidney failure (N17-N19).

Source: CMS ICD-10-CM Tabular List. How to read instructional notes.

Index to Diseases and InjuriesGuidance

Alphabetical index entries that point to this code.

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

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 N01.1 to ICD-9-CMHistory

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

ICD-9-CM
580.4 Ac rapidly progr nephrit
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 2017–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About N01.1Overview

Is N01.1 (Rapidly progressive nephritic syndrome) a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report rapidly progressive nephritic syndrome with focal and segmental glomerular lesions on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

What MS-DRG does N01.1 group to?

When rapidly progressive nephritic syndrome with focal and segmental glomerular lesions is the principal diagnosis on an inpatient stay, it groups to MS-DRG 793, 791, 699, 698, 700, with relative weights from 0.6740 to 4.2192 depending on complications. Higher weights mean higher Medicare reimbursement.

Is N01.1 a CC or MCC?

CMS lists N01.1 as an MCC (major complication or comorbidity) for FY 2027. Reported as a secondary diagnosis, it places the inpatient stay in the highest-weighted DRG of its severity family. It does not count when the principal diagnosis is one of the 286 closely related codes in its exclusion list.

Can N01.1 be reported with a code from N05?

Not as a rule. The Excludes1 note at N01, which applies to N01.1, lists "nephritic syndrome NOS (N05.-)". An Excludes1 note means the excluded code is never reported together with this one; the only exception is when the two conditions are unrelated to each other (Official Guidelines, Section I.A.12.a).

What is the ICD-9 equivalent of N01.1?

Under the General Equivalence Mappings, rapidly progressive nephritic syndrome with focal and segmental glomerular lesions converts to ICD-9-CM 580.4 (ac rapidly progr nephrit). The mapping is approximate, so confirm the match fits the documentation.

Does N01.1 risk-adjust for Medicare Advantage payment?

Not for Medicare Advantage: N01.1 maps to no category in the CMS-HCC V28 model. It still risk-adjusts in the ESRD (V21) category 141 (Nephritis).