2027 ICD-10-CM Diagnosis Code N00.AAcute nephritic syndrome with C3 glomerulonephritis

ICD-10-CM Codes›N00–N99›N00-N08›N00

ICD-10-CM N00.A
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

N00.A is a billable ICD-10-CM diagnosis code for acute nephritic syndrome with C3 glomerulonephritis. 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 116 closely related codes. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Nephritis; nephrosis; renal sclerosis.

N00.A 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
N00.A
Billable Status
Yes — Valid for Submission
Code Describes
Acute nephritic syndrome with C3 glomerulonephritis
Short Description
Acute nephritic syndrome with C3 glomerulonephritis
Same as the full description in the CMS dataset.
Parent Code
N00
Acute nephritic syndrome

Code Classification

ChapterN00–N99Diseases of the genitourinary system
SectionN00-N08Glomerular diseases
CategoryN00Acute nephritic syndrome
This CodeN00.AAcute nephritic syndrome with C3 glomerulonephritis

Medicare Risk Adjustment (HCC)Billing

N00.A 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
N00.A 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.

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to N00.A: its own notes plus those printed at N00, 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 N00 Acute nephritic syndrome applies to 13 codes
  • acute glomerular disease
  • acute glomerulonephritis
  • acute 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.

  • Acute nephritic syndrome with C3 glomerulopathy, NOS

Excludes1

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

On N00.A itself
  • Acute nephritic syndrome (with C3 glomerulopathy) with dense deposit disease (N00.6)
From N00 Acute nephritic syndrome applies to 13 codes
  • acute tubulo-interstitial nephritis (N10)
  • 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.

Referenced in Other NotesGuidance

Instructional notes printed at other codes that name N00.A, its category, or a range that includes it.

Excludes1 2

These codes carry an Excludes1 note naming N00.A: they are not reported together with it, unless the two conditions are unrelated.

  • N00.5 Acute nephritic syndrome with diffuse mesangiocapillary glomerulonephritis
    Acute nephritic syndrome with C3 glomerulonephritis (N00.A)
  • N00.5 Acute nephritic syndrome with diffuse mesangiocapillary glomerulonephritis
    Acute nephritic syndrome with C3 glomerulopathy (N00.A)

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.

Code History & ChangesHistory

Replacement N00.A replaces the following previously assigned code(s):

  • N00.8 - Acute nephritic syndrome with other morphologic changes
FY 2021AddedAdded to the ICD-10-CM code setEffective October 1, 2020.
FY 2022–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About N00.AOverview

What is the ICD-10 code for acute nephritic syndrome with C3 glomerulonephritis?

The ICD-10-CM code for acute nephritic syndrome with C3 glomerulonephritis is N00.A (sometimes written as N00A). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

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

Yes. This is a billable ICD-10-CM code, specific enough to report acute nephritic syndrome with C3 glomerulonephritis on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

What MS-DRG does N00.A group to?

When acute nephritic syndrome with C3 glomerulonephritis 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 N00.A a CC or MCC?

CMS lists N00.A 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 116 closely related codes in its exclusion list.

Can N00.A be reported with N00.6?

Not as a rule. The Excludes1 note on N00.A lists "Acute nephritic syndrome (with C3 glomerulopathy) with dense deposit disease (N00.6)". 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).

Does N00.A risk-adjust for Medicare Advantage payment?

Not for Medicare Advantage: N00.A maps to no category in the CMS-HCC V28 model. It still risk-adjusts in the ESRD (V21) category 141 (Nephritis).