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

Coding instructions

Official Tabular Instructional Notes: the inclusion, exclusion and sequencing notes published for N06.21 in the official ICD-10-CM tabular list, quoted as published.

Source: CMS/CDC — ICD-10-CM Tabular ListRelease: FY2026Effective: October 1, 2025

Notes without a marker are published on N06.21 itself; “inherited from” names the category or block whose note applies here.

Coder workflow for N06.21

MedCoder structured workflow — derived from this code’s own official record

Before you code N06.21

1. N06.21’s title joins a condition with an associated condition or complication. Confirm each component is documented. Where the classification presumes the link through the “with” convention, only a provider statement that the conditions are unrelated defeats it. A combination code is assigned only when it fully identifies the documented conditions; a required second code for the stage, type or manifestation is still reported when the notes ask for it (Guidelines I.B.9, I.A.15).

   Guide: Combination codes →

2. Check the Excludes1 note: if the documentation supports a condition named there, do not simply proceed with N06.21. Excludes1 conditions are not reported together with this code unless the record shows they are unrelated (Guidelines I.A.12.a).

   See the official tabular notes

Choose the right path

1. Does the documentation support a condition named in N06.21’s Excludes1 note?
   Yes → Do not simply proceed: review the excluded code. Both are reported only when the record shows the two conditions are unrelated.
   No → Continue.

   ReviewN04.21, R80.0, I12

Consider N06.21. Then review the Code Also note, and confirm the code is valid for the date of service in the Verify section.

Documentation check

The provider’s diagnostic statement

Codes are assigned from the provider’s documented diagnosis, not from clinical criteria, test values or a medication list (Guidelines I.A.19).

The associated condition or complication

Whether the associated condition the title names is documented; the “with” convention presumes some links, and a provider statement that the conditions are unrelated defeats it (Guidelines I.A.15).

Official instructions as workflow

• Excludes1 — check before selecting N06.21(3 notes)

  Coding workflow: If the documentation supports a condition named in this note, do not simply proceed with N06.21: the two are not reported together. The one exception is when the record shows the two conditions are unrelated to each other.

  CompareN04.21, R80.0, I12

  See the official tabular notes · Guidelines I.A.12.a

• Code Also — related condition(1 note)

  Coding workflow: Review the related condition when both are documented and the instruction applies. A Code Also note does not fix sequencing; the order follows the circumstances of the encounter.

  See the official tabular notes · Guidelines I.A.17

Coding decision scenarios

Pattern scenarios for this code’s structure — decision rules, not clinical cases

Every row is derived from this code’s own record — its title, tabular notes, 7th-character family and same-category siblings — with fixed MedCoder wording; nothing is inferred about a patient. The official notes and guideline text are in the sections each row links to, and they control.

Indexed Clinical Terms (1)

Official source data — entries quoted as published, in the Index’s own lookup phrasing

Clinical term phrases from the official ICD-10-CM Index to Diseases and Injuries that map to this code. These are alphabetic-index entries shown as the Index writes them — lookup phrasing, not necessarily the wording of a final diagnosis.

• Nephropathy, membranous (diffuse), primary

Don’t confuse N06.21 with…

MedCoder analysis — pairs from this code’s official notes, distinctions written by MedCoder

The codes most likely to be picked instead of N06.21 — named in its own official notes, or sharing its laterality or encounter family — with what separates them and which documentation moves the case. Each links to the full comparison.

• N04.21— Excludes1 conflict (Excludes1 — generally not reported together)

  Not coded here — the tabular list excludes this pair for the same encounter.

  Not reported together with this code, except where the two conditions are documented as unrelated.

  What moves you there: Documentation of primary membranous nephropathy with nephrotic syndrome moves the case to N04.21; the two are not reported together unless documented as unrelated.

  Full comparison: N06.21 vs N04.21 →

• R80.0— Excludes1 conflict (Excludes1 — generally not reported together)

  Not coded here — the tabular list excludes this pair for the same encounter.

  Not reported together with this code, except where the two conditions are documented as unrelated.

  What moves you there: Documentation of Proteinuria not associated with specific morphologic lesions moves the case to R80.0; the two are not reported together unless documented as unrelated.

  Full comparison: N06.21 vs R80.0 →

• I12— Excludes1 conflict (Excludes1 — generally not reported together)

  Not coded here — the tabular list excludes this pair for the same encounter.

  Not reported together with this code, except where the two conditions are documented as unrelated.

  What moves you there: Documentation of hypertensive chronic kidney disease moves the case to I12; the two are not reported together unless documented as unrelated.

  Full comparison: N06.21 vs I12 →

• N06.20— Specificity relationship (Review)

  Overlapping diagnoses in the same category.

  Overlapping codes in the same category — the documentation decides which is the more specific fit.

  What moves you there: A record that documents no more than “Isolated proteinuria with diffuse membranous glomerulonephritis, unspecified” takes N06.20; specificity in the record moves it back here.

  Full comparison: N06.21 vs N06.20 →

Relationships are read from this code's own official notes, its laterality siblings and its encounter family; the wording of each distinction is MedCoder editorial, and the documentation named in each “what moves you there” line is the official note phrase or sibling title itself. Source: CMS ICD-10-CM tabular instructional notes; ICD-10-CM Official Guidelines, Section I.A.12.a.

Verify Before Coding

• CC as a secondary diagnosis (FY2026). Can raise the stay's MS-DRG severity tier.

From the code registry, the Medicare Code Editor, and the MS-DRG Definitions Manual. Check it against a full claim in Claim Check.

Relationships & Classification

MedCoder structured relationships — computed from published CMS and AHRQ datasets

Other codes that name N06.21 or its code family, from the CMS ICD-10-CM tabular instructional notes. Tabular-note edges are stored at the code family level that carries each note.

Referenced by 1 Excludes1 note: R80.0 — Isolated proteinuria (via N06.-).

These codes’ tabular lists mark this diagnosis as mutually exclusive — not reported together unless the conditions are documented as unrelated.

MS-DRG Grouper Relationships (FY2026)

Potential MS-DRG participation — not a DRG assignment.

FY2026 MS-DRG: CC — Complication or Comorbidity. Reported as a secondary diagnosis, this code raises the stay's MS-DRG severity tier — except when the principal diagnosis is one of 270 clinically related codes on its CMS exclusion list.

Named in the grouper logic of 3 MS-DRGs: DRG 698 (MDC 11), DRG 699 (MDC 11), DRG 700 (MDC 11).

From the CMS MS-DRG Definitions Manual (Appendices B and C). Actual DRG assignment depends on the complete claim.

Clinical classification (AHRQ CCSR):GEN010 — Proteinuria (default); GEN001 — Nephritis; nephrosis; renal sclerosis.

Clinical Classifications Software Refined (CCSR) for ICD-10-CM Diagnoses. Healthcare Cost and Utilization Project (HCUP), Agency for Healthcare Research and Quality.

Related Codes

Same clinical process (MS-DRG)

Acts as CC — raises the severity of other admissions. CMS groups these diagnoses into one MS-DRG principal-diagnosis exclusion process — a CC/MCC on this list never raises severity when the principal diagnosis is also on it.

N05.4 — Unspecified nephritic syndrome with diffuse endocapillary proliferative glomerulonephritis, N05.5 — Unspecified nephritic syndrome with diffuse mesangiocapillary glomerulonephritis, N05.6 — Unspecified nephritic syndrome with dense deposit disease, N05.7 — Unspecified nephritic syndrome with diffuse crescentic glomerulonephritis, N05.8 — Unspecified nephritic syndrome with other morphologic changes, N05.9 — Unspecified nephritic syndrome with unspecified morphologic changes, N05.A — Unspecified nephritic syndrome with C3 glomerulonephritis, N06.0 — Isolated proteinuria with minor glomerular abnormality, N06.1 — Isolated proteinuria with focal and segmental glomerular lesions, N06.20 — Isolated proteinuria with diffuse membranous glomerulonephritis, unspecified, N06.22 — Secondary membranous nephropathy with isolated proteinuria, N06.29 — Other isolated proteinuria with diffuse membranous glomerulonephritis, N06.3 — Isolated proteinuria with diffuse mesangial proliferative glomerulonephritis, N06.4 — Isolated proteinuria with diffuse endocapillary proliferative glomerulonephritis, N06.5 — Isolated proteinuria with diffuse mesangiocapillary glomerulonephritis, N06.6 — Isolated proteinuria with dense deposit disease, N06.7 — Isolated proteinuria with diffuse crescentic glomerulonephritis, N06.8 — Isolated proteinuria with other morphologic lesion, N06.9 — Isolated proteinuria with unspecified morphologic lesion, N06.A — Isolated proteinuria with C3 glomerulonephritis, +249 more

Same clinical category (CCSR)

AHRQ's Clinical Classifications Software groups these diagnoses under the same clinical categories (Proteinuria, Nephritis; nephrosis; renal sclerosis).

N05.5 — Unspecified nephritic syndrome with diffuse mesangiocapillary glomerulonephritis, N05.6 — Unspecified nephritic syndrome with dense deposit disease, N05.7 — Unspecified nephritic syndrome with diffuse crescentic glomerulonephritis, N05.8 — Unspecified nephritic syndrome with other morphologic changes, N05.9 — Unspecified nephritic syndrome with unspecified morphologic changes, N05.A — Unspecified nephritic syndrome with C3 glomerulonephritis, N06.0 — Isolated proteinuria with minor glomerular abnormality, N06.1 — Isolated proteinuria with focal and segmental glomerular lesions, N06.2 — Isolated proteinuria with diffuse membranous glomerulonephritis, N06.20 — Isolated proteinuria with diffuse membranous glomerulonephritis, unspecified, N06.22 — Secondary membranous nephropathy with isolated proteinuria, N06.29 — Other isolated proteinuria with diffuse membranous glomerulonephritis, N06.3 — Isolated proteinuria with diffuse mesangial proliferative glomerulonephritis, N06.4 — Isolated proteinuria with diffuse endocapillary proliferative glomerulonephritis, N06.5 — Isolated proteinuria with diffuse mesangiocapillary glomerulonephritis, N06.6 — Isolated proteinuria with dense deposit disease, N06.7 — Isolated proteinuria with diffuse crescentic glomerulonephritis, N06.8 — Isolated proteinuria with other morphologic lesion, N06.9 — Isolated proteinuria with unspecified morphologic lesion, N06.A — Isolated proteinuria with C3 glomerulonephritis, +130 more

Same Index main term, other category

The ICD-10-CM Index to Diseases and Injuries files this code under the main term “Nephropathy”; these codes share that main term but sit in a different category of the Tabular List.

N02.B2 — Recurrent and persistent immunoglobulin A nephropathy with focal and segmental glomerular lesion (IgA, with, glomerular lesion, focal and segmental), N02.B3 — Recurrent and persistent immunoglobulin A nephropathy with diffuse membranoproliferative glomerulonephritis (IgA, with, glomerulonephritis, membranoproliferative), N02.B4 — Recurrent and persistent immunoglobulin A nephropathy with diffuse membranous glomerulonephritis (IgA, with, glomerulonephritis, membranous), N02.B5 — Recurrent and persistent immunoglobulin A nephropathy with diffuse mesangial proliferative glomerulonephritis (IgA, with, glomerulonephritis, mesangial proliferative), N02.B6 — Recurrent and persistent immunoglobulin A nephropathy with diffuse mesangiocapillary glomerulonephritis (IgA, with, glomerulonephritis, mesangiocapillary), N02.B9 — Other recurrent and persistent immunoglobulin A nephropathy (IgA, proliferative NEC), N04.20 — Nephrotic syndrome with diffuse membranous glomerulonephritis, unspecified (membranous, with, nephrotic syndrome), N04.21 — Primary membranous nephropathy with nephrotic syndrome (membranous, primary, with nephrotic syndrome), N04.22 — Secondary membranous nephropathy with nephrotic syndrome (membranous, secondary, with nephrotic syndrome), N05.8 — Unspecified nephritic syndrome with other morphologic changes (proliferative NEC), N07.0 — Hereditary nephropathy, not elsewhere classified with minor glomerular abnormality (hereditary NEC, with, minor glomerular abnormality), N07.1 — Hereditary nephropathy, not elsewhere classified with focal and segmental glomerular lesions (hereditary NEC, with, focal and segmental glomerular lesions), N07.2 — Hereditary nephropathy, not elsewhere classified with diffuse membranous glomerulonephritis (hereditary NEC, with, diffuse, membranous glomerulonephritis), N07.3 — Hereditary nephropathy, not elsewhere classified with diffuse mesangial proliferative glomerulonephritis (hereditary NEC, with, diffuse, mesangial proliferative glomerulonephritis), N07.4 — Hereditary nephropathy, not elsewhere classified with diffuse endocapillary proliferative glomerulonephritis (hereditary NEC, with, diffuse, endocapillary proliferative glomerulonephritis), N07.5 — Hereditary nephropathy, not elsewhere classified with diffuse mesangiocapillary glomerulonephritis (hereditary NEC, with, diffuse, mesangiocapillary glomerulonephritis), N07.6 — Hereditary nephropathy, not elsewhere classified with dense deposit disease (hereditary NEC, with, dense deposit disease), N07.7 — Hereditary nephropathy, not elsewhere classified with diffuse crescentic glomerulonephritis (hereditary NEC, with, diffuse, crescentic glomerulonephritis), N07.8 — Hereditary nephropathy, not elsewhere classified with other morphologic lesions (hereditary NEC, with, specified morphological changes NEC), N07.9 — Hereditary nephropathy, not elsewhere classified with unspecified morphologic lesions (hereditary NEC), +22 more

Lab tests where this diagnosis supports Medicare coverage (NCD)

Medicare's National Coverage Determination (NCD) program lists this diagnosis as medical justification for these lab tests.

Gamma-glutamyl Transferase (GGT) Test

Contextual Map

Every relationship of N06.21 in one view: hierarchy, official tabular instructions in both directions, clinical classification, risk adjustment, MS-DRG participation, index terms and change history — each edge carrying the CMS source it derives from.

Run N06.21 with these 2 related codes in Claim Check

Hierarchy

• N00-N99 — Chapter 14: Diseases of the Genitourinary System (N00-N99) (N00-N99)[Hierarchy]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• N00-N08 — Glomerular diseases[Hierarchy]— CMS ICD-10-CM tabular structure · icd10cm-fy2026

Excludes1

• N04.21 — Primary membranous nephropathy with nephrotic syndrome[Excludes1]: “primary membranous nephropathy with nephrotic syndrome (N04.21)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026

Referenced by Excludes1 notes

• R80.0 — Isolated proteinuria[Excludes1](via N06.-): “isolated proteinuria with specific morphological lesion (N06.-)”— CMS ICD-10-CM tabular instructional notes · icd10cm-fy2026

Clinical classification (CCSR)

• GEN010 — Proteinuria[CCSR]— AHRQ CCSR for ICD-10-CM Diagnoses (HCUP)
• GEN001 — Nephritis; nephrosis; renal sclerosis[CCSR]— AHRQ CCSR for ICD-10-CM Diagnoses (HCUP)

MS-DRG Grouper

• CC — Complication or Comorbidity [MS-DRG severity]: “As a secondary diagnosis this code can raise the stay's MS-DRG severity tier (CC).”— CMS MS-DRG Definitions Manual (Appendix C) · FY2026
• DRG 698 — OTHER KIDNEY AND URINARY TRACT DIAGNOSES WITH MCC[MS-DRG]: “OTHER KIDNEY AND URINARY TRACT DIAGNOSES WITH MCC (MDC 11)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026
• DRG 699 — OTHER KIDNEY AND URINARY TRACT DIAGNOSES WITH CC[MS-DRG]: “OTHER KIDNEY AND URINARY TRACT DIAGNOSES WITH CC (MDC 11)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026
• DRG 700 — OTHER KIDNEY AND URINARY TRACT DIAGNOSES WITHOUT CC/MCC[MS-DRG]: “OTHER KIDNEY AND URINARY TRACT DIAGNOSES WITHOUT CC/MCC (MDC 11)”— CMS MS-DRG Definitions Manual (Appendix B) · FY2026

MDC crossing

• MDC 11 — Diseases and Disorders of the Kidney and Urinary Tract[MDC crossing]: “Diseases and Disorders of the Kidney and Urinary Tract — the grouper's crossing between diagnoses and procedures: a principal diagnosis sets the MDC, and same-MDC procedures move the stay to its surgical DRGs. 3,574 same-MDC procedures group here; browse them on the MDC page.”— CMS MS-DRG Definitions Manual · FY2026

Index entries

• Nephropathy, membranous (diffuse), primary[Index term]— CMS ICD-10-CM Index to Diseases and Injuries · icd10cm-fy2026

Nearest codes (15)

• N06 — Isolated proteinuria with specified morphological lesion[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• N06.0 — Isolated proteinuria with minor glomerular abnormality[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• N06.1 — Isolated proteinuria with focal and segmental glomerular lesions[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• N06.2 — Isolated proteinuria with diffuse membranous glomerulonephritis[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• N06.20 — Isolated proteinuria with diffuse membranous glomerulonephritis, unspecified[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• N06.22 — Secondary membranous nephropathy with isolated proteinuria[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• N06.29 — Other isolated proteinuria with diffuse membranous glomerulonephritis[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• N06.3 — Isolated proteinuria with diffuse mesangial proliferative glomerulonephritis[Sibling]— CMS ICD-10-CM tabular structure · icd10cm-fy2026
• and 7 more

Change history

• FY2024 — Added to the code set[Change history]— CMS release files (code change ledger) · icd10cm-fy2024

Sources for this page

Codes, titles, notes, index terms and mappings on this page are transcribed from the datasets below. Relationships MedCoder computed and text MedCoder wrote are labelled where they appear.

Code, title, tabular notes and index terms Official source data

CMS/CDC ICD-10-CM FY2026 tabular list, index and tables, effective October 1, 2025 Release, file and checksum · Publisher’s page

Claim edits Official source data

CMS Definitions of Medicare Code Edits — v43.1 (April 2026) Release, file and checksum · Publisher’s page

Inpatient payment groups Official source data

CMS MS-DRG Definitions Manual (incl. Appendix B diagnosis index, Appendix C CC/MCC list, Appendix E procedure index) and IPPS Final Rule tables — v43 Release, file and checksum · Publisher’s page

Change history and date-of-service validity Official source data

CMS ICD-10-CM release addenda, ingested release by release into the change ledger Release, file and checksum · Publisher’s page

Comparisons, relationships and the contextual map MedCoder structured relationship

Computed by MedCoder from the tabular notes and tables above; every derived relationship is marked as derived where it appears

Summary and FAQ answers MedCoder explanation

Written by MedCoder to explain the sources above: drafted with AI assistance, checked by a person against the release files, and labelled as MedCoder text where it appears. Not official text.

Labels on this page: Official source data · MedCoder structured relationship · MedCoder explanation. How to read the labels · All data sources and release dates

Nearest Codes in This Family

Official ICD-10-CM classifications closest to N06.21 in its code family, with their registry titles.

• N06 — Isolated proteinuria with specified morphological lesion
• N06.0 — Isolated proteinuria with minor glomerular abnormality
• N06.1 — Isolated proteinuria with focal and segmental glomerular lesions
• N06.2 — Isolated proteinuria with diffuse membranous glomerulonephritis
• N06.20 — Isolated proteinuria with diffuse membranous glomerulonephritis, unspecified
• N06.22 — Secondary membranous nephropathy with isolated proteinuria
• N06.29 — Other isolated proteinuria with diffuse membranous glomerulonephritis
• N06.3 — Isolated proteinuria with diffuse mesangial proliferative glomerulonephritis
• N06.4 — Isolated proteinuria with diffuse endocapillary proliferative glomerulonephritis
• N06.5 — Isolated proteinuria with diffuse mesangiocapillary glomerulonephritis

View all codes in the N06 family