N04.B1
BillableNephrotic syndrome with idiopathic immune complex membranoproliferative glomerulonephritis (IC-MPGN)
Last updated: FY2026 ICD-10-CM (Oct 1, 2025 – Sep 30, 2026) | CMS-HCC V28 (100% phase-in, PY2026)
Is N04.B1 an HCC code?
No. N04.B1 is a billable ICD-10-CM code but does not map to any HCC category in V28, V24, ESRD, or RxHCC.
This code does not map to an HCC category in any model (V28, V24, ESRD, RxHCC).
What This Code Means
N04.B1 is the ICD-10-CM diagnosis code for nephrotic syndrome with idiopathic immune complex membranoproliferative glomerulonephritis (ic-mpgn). A kidney condition where protein leaks into the urine due to a primary immune system disorder affecting the kidney's filtering units with a specific pattern of inflammation. N04.B1 sits in the ICD-10-CM chapter for diseases of the genitourinary system (n00-n99), within the section covering glomerular diseases (n00-n08).
N04.B1 is a billable ICD-10-CM code but does not map to a payment HCC under the CMS-HCC V28, V24, ESRD, or RxHCC risk adjustment models. It can be reported on Medicare Advantage encounter data submissions but it does not contribute to a beneficiary's RAF score and therefore does not affect risk-adjusted payments to the plan.
The 'idiopathic' designation means the condition is primary (not secondary to another disease).
HCC Buddy maintains structured V28 and V24 mapping, RAF weights, and MEAT documentation criteria for N04.B1 sourced directly from the CMS-HCC risk adjustment model files and the CMS ICD-10-CM code set.
Coding Tips
- •The 'idiopathic' designation means the condition is primary (not secondary to another disease)
- •Requires kidney biopsy confirmation showing immune complex deposits and membranoproliferative pattern