N06.21 — Primary membranous nephropathy with isolated proteinuria
N06.21 is a billable, specific ICD-10-CM code for primary membranous nephropathy with isolated proteinuria. It is valid for submission on a claim.
Excludes1 — never code together
These conditions cannot occur together. Billing both on the same encounter is a denial.
- primary membranous nephropathy with nephrotic syndrome (N04.21)
Inclusion terms
Alternative wordings a physician may use in the chart for this same code.
- Idiopathic membranous nephropathy (with isolated proteinuria)
- Primary membranous nephropathy, NOS
Excludes1 inherited from the categories above N06.21
These are not written on N06.21, but they bind it: a note on a category applies to every code beneath it. Billing N06.21 with anything listed here is a denial.
Other codes that can never be billed with N06.21
These codes carry an Excludes1 note pointing at N06.21. The conflict binds both ways, but ICD-10-CM only writes it down on one side — so you would not find this by reading N06.21 alone.
- R80.0Isolated proteinuria
Risk adjustment
N06.21 does not map to an HCC and does not risk-adjust under CMS-HCC V28. That is normal — most ICD-10 codes do not. It still needs to be coded correctly; it just will not move a RAF score.
Medicare coverage
N06.21 is named in 3 Medicare coverage policies — 3 listing it as supporting medical necessity. Which of them applies to you depends on your Medicare contractor, and coverage genuinely differs by state.
- A55336Billing and Coding: Retroperitoneal Ultrasound
- A57189Billing and Coding: Serum Magnesium
- A59186Billing and Coding: Magnesium
How N06.21 is indexed
Coders do not find codes by browsing the tabular list — they look them up in the alphabetic index, under the word the physician wrote. These are the index entries that lead here, so you can see which chart wordings map to N06.21.
- Nephropathy›membranous›primary
Code history
N06.21 has not changed since FY2024 — no addition, revision or deletion across the three most recent ICD-10-CM releases.
Related codes at this level
Codes that share N06.2. If N06.21 is not quite right, the correct code is usually one of these.
Questions about N06.21
- Is N06.21 a billable ICD-10-CM code?
- Yes. N06.21 is a billable, specific ICD-10-CM code and is valid for submission on a claim.
- Where does N06.21 sit in the tabular list?
- Diseases of the genitourinary system (N00-N99), in the block Glomerular diseases (N00-N08).
- What cannot be coded together with N06.21?
- N06.21 carries Excludes1 notes, which means the conditions they list can never be coded together with it on the same encounter. Some are written on the categories above N06.21 (N06) and apply to it just the same.