ICD code N06.0 – Isolated proteinuria with minor glomerular abnormality

Key takeaways

N06.0 applies to isolated proteinuria with a documented minor glomerular abnormality, not to proteinuria that is still being worked up

The fourth character comes from documented histology, so the record needs a biopsy report or an explicit physician statement of the lesion

Minimal change disease maps to N06.0 only when the picture is isolated proteinuria; nephrotic syndrome features send the same histology to N04.0

The N06 category carries a single Excludes1 note, covering proteinuria not associated with a specific morphologic lesion (R80.0)

Pabau’s claims management software captures ICD-10-CM codes at the point of documentation and submits through the Claim.MD clearinghouse

ICD-10 code N06.0 at a glance

ICD-10 code N06.0 is the billable diagnosis code for isolated proteinuria with minor glomerular abnormality. It applies when the record documents protein loss without nephrotic syndrome, alongside a minor glomerular lesion. The code sits within the N00-N08 glomerular diseases block, Chapter 14 of the CDC/NCHS ICD-10-CM web tool. The table below summarizes the reference data coders check first.

What N06.0 covers: full code descriptor and clinical meaning

Isolated proteinuria is significant protein loss in the urine without the full clinical picture of nephrotic syndrome. The patient has no edema, no hypoalbuminemia, and no hyperlipidemia. The minor glomerular abnormality qualifier refers to a histologic finding on kidney biopsy, or one documented by the treating physician. It describes minimal or no structural glomerular damage at the light microscopy level.

Minimal change disease is the most commonly cited condition in this category. On light microscopy the glomeruli appear normal. Even so, the abnormality shows only on electron microscopy, as podocyte foot process effacement. Mesangial hypercellularity can also qualify as a minor glomerular abnormality, depending on biopsy interpretation.

The fourth-character subcategory across the N06 block is driven entirely by the histologic qualifier. That qualifier must come from a biopsy report, or from explicit physician documentation stating the lesion type. Without either, the coder cannot validate N06.0 over another N06 subcode.

N06.0 within the N06 category: subcategory map

All N06 subcodes share the same parent descriptor, and they differ only by the fourth character. That character identifies the histologic finding, so the biopsy report or the physician-documented lesion type decides which one you assign. The FY2026 range runs from N06.0 through N06.9, plus N06.A.

What the N06 Excludes1 note actually says

The N06 category carries one Excludes1 note, and it is narrower than most coders expect. The note reads: proteinuria not associated with specific morphologic lesion (R80.0). Even so, nothing in the tabular list bars N06 from sharing a claim with the other N00-N08 categories, or with chronic kidney disease.

• What the note does: it keeps the R80.0 symptom code off a claim that already carries a documented morphologic lesion. One or the other, never both.
• What it does not do: it does not create a blanket bar on N04, N05, or any other glomerular category. Instead, those decisions run on documentation, not on an Excludes1 edit.
• Why N06.0 and N04.0 still conflict: both describe the same episode with a different clinical syndrome attached. As a result, billing the pair goes against the record, and a reviewer reads it as an unresolved diagnosis.
• Where comorbidities fit: chronic kidney disease, hypertensive kidney disease, and diabetic kidney disease are coded alongside N06.0 whenever the record documents them.

N06.0 vs R80: choosing between the definitive code and the symptom code

R80.x codes represent proteinuria as a symptom, used only when a definitive glomerular diagnosis has not been established. Once the physician documents a confirmed diagnosis with a specified morphological lesion, the appropriate N06 code displaces R80.x. In fact, the ICD-10-CM Official Guidelines are explicit on this point. Symptom codes are not used when a definitive diagnosis is documented.

N06.0 vs N04.0 vs N05.0: key differentiators

This is the most important distinction in the N00-N08 block for coders working with minimal change disease patients. In short, the clinical syndrome determines the code category, and the biopsy finding sets the fourth character within it.

A patient with biopsy-proven minimal change disease, significant edema, serum albumin below 3.0 g/dL and a urine protein-to-creatinine ratio above 3.5 g/g belongs in N04.0. By contrast, the same biopsy finding in a patient with asymptomatic proteinuria and no nephrotic triad maps to N06.0. Coders who anchor to the biopsy result and ignore the clinical syndrome invite medical-necessity denials.

Two questions settle almost every case, and they run in a fixed order. The chart below walks the record from a first proteinuria result to a fourth character.

Documentation requirements to support N06.0

The medical record must contain specific elements before N06.0 is coded. The fourth-character qualifier depends on documented detail, never on coder inference. Likewise, the same standard runs through medical billing compliance work more broadly, where an auditor reads the note rather than the claim line. For N06.0, these are the required elements.

• Confirmed diagnosis: the physician must document isolated proteinuria, or proteinuria without nephrotic syndrome, as a confirmed diagnosis rather than a finding under investigation.
• Morphological qualifier: the record must specify minor glomerular abnormality, minimal glomerular lesion, minimal change disease, or equivalent language. Absent this, N06.9 applies instead.
• Quantification method: a 24-hour urine protein or UPCR result should be documented. It confirms the isolated proteinuria and supports medical necessity for the nephrology services billed alongside the code.
• Exclusion of nephrotic syndrome features: the clinical note should document the absence of edema, a normal or near-normal serum albumin, and the absence of hyperlipidemia.
• Biopsy report or physician statement: a biopsy report identifying the histologic finding is the strongest support. Where no biopsy was performed, the treating nephrologist must document the morphological diagnosis explicitly. Coders may not infer the fourth character from a biopsy-pending note.

Coding N06.0 with comorbidities: CKD, hypertension, and diabetes

N06.0 does not include or assume chronic kidney disease. Instead, the two conditions are separately coded when both are documented. According to CMS ICD-10-CM coding guidance, instructional notes in the Tabular List direct coders to assign additional codes for associated conditions.

A patient with isolated proteinuria from minimal change disease, Stage 3a CKD (eGFR 45-59 ml/min) and hypertension needs N06.0, N18.31 and I12.9 at minimum. The CKD stage must reflect the GFR lab values in the record, not the physician’s own severity assessment.

Payer requirements and prior authorization for N06.0 claims

N06.0 alone is not a high-risk or high-cost code, so it rarely triggers prior authorization. Instead, the diagnostic and therapeutic procedures around it often do. Percutaneous kidney biopsy, immunosuppressant therapy and repeat nephrology visits often require pre-authorization under Medicare Advantage and commercial plans. So, practices submitting claims online should route them through a clearinghouse that validates ICD-10-CM codes against payer edits first.

From a Medicare inpatient perspective, N06.0 groups under the kidney and urinary tract diagnosis categories of the MS-DRG system. CMS runs version 43.0 for FY2026, updated to version 43.1 in April 2026. The DRG assignment depends on the procedures billed alongside the diagnosis and on any complications or comorbidities. For outpatient claims, the Ambulatory Payment Classification follows the CPT procedure code rather than the diagnosis.

Local Coverage Determination policies for nephrology services vary from one Medicare Administrative Contractor to another. So, practices should check whether their MAC has an active LCD covering kidney biopsy or proteinuria diagnostic services. The next check is whether that LCD lists N06.0 as a covered indication. Pre-submission edits catch an LCD mismatch before the payer does.

Common claim denial reasons for N06.0 and how to prevent them

N06.0 claims fail for five predictable reasons, and each has a documentation or coding fix. The remittance advice usually carries CARC 4, CARC 16 or CARC 97. Those mean the service does not match the diagnosis, the claim lacks information needed for adjudication, or payment sits in another service’s allowance. The full set of denial reason codes maps each one to the correction it calls for.

• Using R80.x when a definitive diagnosis is documented: once the nephrologist documents isolated proteinuria with a minor glomerular abnormality, R80.x no longer applies. Flag any R80.x assignment where an N06-supporting note exists in the same encounter.
• Missing the fourth-character histologic qualifier: submitting N06.0 without supporting documentation triggers a medical-necessity denial or a records request. Make the morphological qualifier a required field in the nephrology note template.
• Coding N06.0 when nephrotic syndrome features are present: where the chart documents edema and hypoalbuminemia, N04.0 applies instead. Add a documentation improvement query that asks the physician to confirm the syndrome type.
• Billing N06.0 and N04.0 on the same claim: the pair describes one episode two contradictory ways, and a reviewer treats the diagnosis as unresolved. One category per episode, chosen from the syndrome.
• Missing medical necessity for associated procedures: a kidney biopsy CPT code billed with N06.0 needs a note establishing why the biopsy was necessary. Connect the biopsy to the proteinuria workup in the order note.

Denial work starts before submission. Running pre-submission edit checks through a clearinghouse clears most CARC 4 and CARC 97 rejections before they turn into rework.

ICD-10-CM 2026 status: is N06.0 valid for the current fiscal year?

N06.0 is valid for FY2026 claims, covering October 1, 2025 through September 30, 2026. In fact, the CMS ICD-10-CM FY2026 release published no descriptor changes, addenda or errata affecting N06.0 or the N06 category. Overall, the descriptor, chapter placement and Excludes1 note are unchanged from FY2025.

Coders can verify current-year status through the CDC/NCHS ICD-10-CM web tool, which publishes the official annual tabular list. CMS releases each new code set in the preceding months, with an effective date of October 1.

How Pabau keeps N06.0 documentation and claims in one place

In most nephrology practices the biopsy report, the clinical note and the claim live in three systems. The coder reads the note in one, checks the lesion type in another, then types N06.0 into a third. As a result, every hop is a chance for the fourth character to land without the documentation that supports it.

Pabau is practice management software that keeps the clinical record and the billing record on the same patient file. The nephrology note, the UPCR result and the morphological qualifier sit beside the diagnosis code the coder assigned. Pabau’s claims software for practices then submits through the Claim.MD clearinghouse, with eligibility checks and claim-level edits ahead of the payer.

When a denial comes back, the ERA lands against the original claim line with its CARC code attached. As a result, your biller can see which N06.0 claim was rejected, and which note to open, without rebuilding the encounter from three exports.

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Conclusion

N06.0 rewards precision in the chart rather than speed at the keyboard. Read the syndrome first, because it decides the category, and read the lesion second, because it sets the fourth character. A biopsy report on its own answers only half of that.

The trade-off worth remembering is that N06.9 is always available and almost always the weaker claim. In short, chasing the physician for the lesion type takes one query today and saves an appeal later. Book a demo to see how Pabau keeps the nephrology note and the claim that depends on it in the same record.

Continue your research

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Want a structured framework for managing denied claims before they age? Denial management in healthcare covers the appeal workflow, timelines, and documentation strategies for overturning preventable denials.

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