2027 ICD-10-CM Diagnosis Code N06.21Primary membranous nephropathy with isolated proteinuria

ICD-10-CM Codes›N00–N99›N00-N08›N06

ICD-10-CM N06.21
CMSSource: CMS FY 2027 ICD-10-CM dataset · Effective Oct 1, 2026 – Sep 30, 2027

N06.21 is a billable ICD-10-CM diagnosis code for primary membranous nephropathy with isolated proteinuria. 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. As a secondary diagnosis, it counts as a complication or comorbidity (CC) and moves an inpatient stay to a higher severity level within its MS-DRG family. It does not count, however, when the principal diagnosis is one of 270 closely related codes. Coders also document this condition as idiopathic glomerulonephritis. In AHRQ's Clinical Classifications Software (CCSR), this diagnosis falls under Nephritis; nephrosis; renal sclerosis and Proteinuria.

N06.21 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
N06.21
Billable Status
Yes — Valid for Submission
Code Describes
Primary membranous nephropathy with isolated proteinuria
Short Description
Primary membranous nephropathy with isolated proteinuria
Same as the full description in the CMS dataset.
Parent Code
N06.2
Isolated proteinuria with diffuse membranous glomerulonephritis

Code Classification

ChapterN00–N99Diseases of the genitourinary system
SectionN00-N08Glomerular diseases
CategoryN06Isolated proteinuria with specified morphological lesion
This CodeN06.21Primary membranous nephropathy with isolated proteinuria

Medicare Risk Adjustment (HCC)Billing

N06.21 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
N06.21 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.

  • Idiopathic glomerulonephritis
  • Idiopathic membranous glomerulonephritis

Instructional NotesGuidance

Instructions from the official ICD-10-CM Tabular List that apply to N06.21: its own notes plus those printed at N06, block N00-N08, and Chapter 14. A note printed at a category, block or chapter applies to every code under it.

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.

  • Idiopathic membranous nephropathy (with isolated proteinuria)
  • Primary membranous nephropathy, NOS

Excludes1

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

On N06.21 itself
  • primary membranous nephropathy with nephrotic syndrome (N04.21)
From N06 Isolated proteinuria with specified morphological lesion applies to 14 codes
  • Proteinuria not associated with specific morphologic lesions (R80.0)
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 N06.21, its category, or a range that includes it.

Excludes1 1

These codes carry an Excludes1 note naming N06.21: they are not reported together with it, unless the two conditions are unrelated.

  • R80.0 Isolated proteinuria
    isolated proteinuria with specific morphological lesion (N06.-) names N06.-, which includes this code

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 No · outpatient No
CCSR GEN010
Proteinuria
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 N06.21 replaces the following previously assigned code(s):

  • N06.2 - Isolated proteinuria w diffuse membranous glomerulonephritis
FY 2024AddedAdded to the ICD-10-CM code setEffective October 1, 2023.
FY 2025–2026No changes
FY 2027CurrentCurrent code set, no changesEffective October 1, 2026 through September 30, 2027.

Questions About N06.21Overview

What is the ICD-10 code for primary membranous nephropathy with isolated proteinuria?

The ICD-10-CM code for primary membranous nephropathy with isolated proteinuria is N06.21 (sometimes written as N0621). It is billable on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

Is N06.21 a billable code?

Yes. This is a billable ICD-10-CM code, specific enough to report primary membranous nephropathy with isolated proteinuria on HIPAA-covered claims from October 1, 2026 through September 30, 2027.

What MS-DRG does N06.21 group to?

When primary membranous nephropathy with isolated proteinuria is the principal diagnosis on an inpatient stay, it groups to MS-DRG 699, 698, 700, with relative weights from 0.6740 to 1.6400 depending on complications. Higher weights mean higher Medicare reimbursement.

Is N06.21 a CC or MCC?

CMS lists N06.21 as a CC (complication or comorbidity) for FY 2027. Reported as a secondary diagnosis, it moves the inpatient stay to a higher-weighted DRG within its severity family. It does not count when the principal diagnosis is one of the 270 closely related codes in its exclusion list.

Can N06.21 be reported with N04.21?

Not as a rule. The Excludes1 note on N06.21 lists "primary membranous nephropathy with nephrotic syndrome (N04.21)". 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 N06.21 risk-adjust for Medicare Advantage payment?

Not for Medicare Advantage: N06.21 maps to no category in the CMS-HCC V28 model. It still risk-adjusts in the ESRD (V21) category 141 (Nephritis).