Secondary membranous nephropathy with isolated proteinuria

This code signifies a kidney disorder characterized by damage to the glomerular basement membrane, leading to protein leakage into the urine, but without the full constellation of symptoms defining nephrotic syndrome. The membranous nephropathy is secondary to another underlying condition, and the proteinuria is the sole significant clinical manifestation.

Use this code when documentation specifies secondary membranous nephropathy and explicitly states "isolated proteinuria" or "non-nephrotic range proteinuria." This applies when the patient exhibits proteinuria due to a secondary cause (e.g., lupus, hepatitis B) but does not meet criteria for nephrotic syndrome (e.g., no significant edema, hypoalbuminemia, or hyperlipidemia).

• Ensure documentation clearly distinguishes "isolated proteinuria" from "nephrotic syndrome."
• Confirm the membranous nephropathy is secondary; if primary, a different code applies.
• Do not code with N04.22 (secondary membranous nephropathy with nephrotic syndrome) due to the Excludes1 note.