N04.21 — Primary membranous nephropathy with nephrotic syndrome
N04.21 is a billable, specific ICD-10-CM code for primary membranous nephropathy with nephrotic syndrome. It is valid for submission on a claim.
Inclusion terms
Alternative wordings a physician may use in the chart for this same code.
- Idiopathic membranous nephropathy with nephrotic syndrome
Other codes that can never be billed with N04.21
These codes carry an Excludes1 note pointing at N04.21. The conflict binds both ways, but ICD-10-CM only writes it down on one side — so you would not find this by reading N04.21 alone.
- N06.21Primary membranous nephropathy with isolated proteinuria
Risk adjustment
N04.21 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
N04.21 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 N04.21 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 N04.21.
- Nephropathy›membranous›idiopathic, with nephrotic syndrome
- Nephropathy›membranous›primary›with nephrotic syndrome
- Nephropathy›membranous›with›nephrotic syndrome›primary
Related codes at this level
Codes that share N04.2. If N04.21 is not quite right, the correct code is usually one of these.
Questions about N04.21
- Is N04.21 a billable ICD-10-CM code?
- Yes. N04.21 is a billable, specific ICD-10-CM code and is valid for submission on a claim.
- Where does N04.21 sit in the tabular list?
- Diseases of the genitourinary system (N00-N99), in the block Glomerular diseases (N00-N08).