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N17.0

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N17.0 - Acute Kidney Failure with Tubular Necrosis

Short Description

N17.0: Use for acute kidney injury (AKI) / acute renal failure when the provider documents acute tubular necrosis (ATN) or renal tubular necrosis - the kidney tubules are acutely damaged and cannot adequately filter waste or balance electrolytes. This is a specific, billable AKI code and maps to HCC 135 (Acute Renal Failure) for risk adjustment.

Full Description & Clinical Context

N17.0 describes acute kidney failure with tubular necrosis - a severe form of AKI where the renal tubules are injured from ischemia (hypoperfusion) or nephrotoxins, leading to abrupt decline in kidney function over hours to days.

  • Official title: Acute kidney failure with tubular necrosis.
  • Includes: Acute tubular necrosis, Renal tubular necrosis, Tubular necrosis NOS.
  • Often due to: prolonged hypotension/shock, sepsis, nephrotoxic drugs, radiographic contrast, rhabdomyolysis.

Clinical picture of ATN (N17.0): decreased urine output (oliguria), rising creatinine/BUN, fluid overload, electrolyte disturbances (esp. hyperkalemia), and possible need for dialysis in severe cases.

Code Details

  • ICD-10-CM code: N17.0
  • Description: Acute kidney failure with tubular necrosis.
  • Synonyms:
    • Acute tubular necrosis (ATN)
    • Renal tubular necrosis
    • Tubular necrosis NOS
  • Code type: Billable/specific diagnosis code.
  • Category: N17 - Acute kidney failure.

Excludes 1 (examples):

  • Traumatic acute renal failure / traumatic anuria → codes in injury/trauma chapter (e.g., T79.5).

Coding note:

  • Code also the associated underlying condition causing ATN (e.g., sepsis, shock, dehydration, nephrotoxic drug exposure).

Pathophysiology & Etiology - When It’s Really N17.0

Tubular necrosis = intrinsic AKI.
Renal tubular cells are injured → sloughing and necrosis → tubular obstruction and back-leak of filtrate → fall in GFR and acute kidney failure.

Common causes of ATN (N17.0):

  • Ischemic ATN: prolonged hypotension, shock, sepsis, major surgery, severe blood loss.
  • Nephrotoxic ATN: aminoglycosides, amphotericin, cisplatin, contrast dye, NSAIDs, toxins.
  • Rhabdomyolysis / hemoglobinuria: myoglobin or hemoglobin-induced tubular injury.
  • Prolonged prerenal azotemia that progresses to structural tubular damage.

Clinical phases of ATN:

  • Initiation → Maintenance (oliguric/anuric) → Recovery (polyuric with improving function).

N17.0 vs N17.9 (and Other N17 Codes)

Use N17.0 ONLY when tubular necrosis is explicitly documented. If AKI is documented without type, default is N17.9.

CodeDescriptionDocumentation Must Say…Use When…
N17.0Acute kidney failure with tubular necrosis“Acute tubular necrosis”, “ATN”, “tubular necrosis”AKI + ATN documented (ischemic or nephrotoxic)
N17.1Acute kidney failure with acute cortical necrosis“Cortical necrosis”Cortical necrosis specifically documented
N17.2Acute kidney failure with medullary necrosis“Medullary necrosis”, “papillary necrosis”Medullary/papillary necrosis documented
N17.8Other acute kidney failureAnother specific AKI type not fitting above
N17.9Acute kidney failure, unspecified“AKI/ARF” but no type/cause documented

Coding principle: if the note says ATN, you should not use N17.9 - code N17.0.

Documentation Requirements for N17.0

To assign N17.0, you need BOTH:

  1. AKI/acute renal failure documented, e.g.:
    • “Acute kidney injury,” “Acute renal failure,” “AKI,” “ARF”.
  2. Tubular necrosis documented, e.g.:
    • “Acute tubular necrosis (ATN),” “Renal tubular necrosis,” “Tubular necrosis.”

Supportive documentation (not strictly required but excellent for audits):

  • Acute rise in creatinine (e.g., ≥0.3 mg/dL in 48 hours or ≥1.5× baseline).
  • Oliguria/anuria (e.g., <0.5 mL/kg/hr or essentially no urine).
  • KDIGO stage (Stage 1-3) if documented.
  • Identified etiology: sepsis, shock, nephrotoxin, contrast, rhabdo, etc.

Warning

Do NOT code N17.0 if:

  • Only AKI is documented (no mention of tubular necrosis) → code N17.9.
  • The kidney problem is purely chronic (CKD) with no acute insult → N18.x only.

HCC Information (Risk Adjustment)

N17.0 (like N17.9) maps to CMS HCC 135 - Acute Renal Failure.

  • HCC: 135 - Acute Renal Failure.
  • Typical RAF weight (recent CMS models): ~0.47 (approximate; check most current model).
  • All qualifying AKI codes (N17.0-N17.2, N17.8, N17.9) roll up to this HCC.

Why it matters:

  • Proper coding of N17.0 ensures the acute severity of illness is captured in risk scores and reimbursement (Medicare Advantage / ACO / risk contracts).
  • Under-coding (missing N17.0) → underestimates patient risk.
  • Over-coding (using N17.0 without documented ATN) → audit exposure.

DRG / Inpatient Impact

When N17.0 is the principal diagnosis, cases typically group into the Renal Failure DRGs (current MS-DRG families):

  • DRG 682 - Renal Failure with MCC
  • DRG 683 - Renal Failure with CC
  • DRG 684 - Renal Failure without CC/MCC

Final DRG depends on documented MCC/CC comorbidities and procedures.

RVU / wRVU Notes

  • ICD-10-CM codes (including N17.0) do NOT have RVUs/wRVUs. RVUs apply to CPT/HCPCS procedure codes only.
  • N17.0 influences DRG payment and HCC risk adjustment, not professional RVUs by itself.

You can, however, link N17.0 to high-complexity E/M services and dialysis procedures to support medical necessity and coding complexity.

Common Associated ICD-10 Codes

Often seen with N17.0 (code underlying causes/complications when documented):

  • Sepsis: A41.9 (or specific organism A41.x).
  • Septic shock: R65.21.
  • Hypotension/shock: I95.9, R57.x.
  • Dehydration: E86.0.
  • Rhabdomyolysis: M62.82.
  • Drug-induced renal failure: T36-T50 series (with 5th/6th characters for drug & intent).
  • Electrolyte disorders: E87.2 (acidosis), E87.5 (hyperkalemia), etc.
  • Chronic kidney disease: N18.1-N18.6 (code in addition if CKD present).

For AKI on CKD, code N17.0 + appropriate N18.x when both are clearly documented.

Common CPT Pairings (Facility/Pro Fee Context)

These procedures commonly appear with N17.0 as a key diagnosis for medical necessity:

RVU values below are approximate and change by year; always check the current Medicare Physician Fee Schedule.

  • G0491 - Dialysis procedure for acute kidney injury in ESRD facility (per day).
  • 90935 / 90937 - Hemodialysis, single evaluation vs. repeated evaluation.
  • 90945 / 90947 - Peritoneal dialysis.
  • 36556 / 36558 - Non-tunneled vs tunneled central venous catheters (dialysis access).
  • 36248 - Selective catheterization for access/angiography.
  • 80047 / 80048 / 80053 - BMP/CMP panels.
  • 81000-81003 - urinalysis.
  • 99283-99285 - ED E/M services for acute presentation.
  • 99221-99223, 99231-99233 - Initial and subsequent inpatient E/M for AKI/ATN.

N17.0 helps justify intensity of services like frequent labs, dialysis, nephrology consultations, and critical care.

Clinical Examples - When N17.0 is Appropriate

✅ Example 1 - Sepsis with ATN

“Septic shock from pneumonia. Now with acute kidney injury. Creatinine rose from 1.0 to 4.5 mg/dL in 24 hours. Nephrology impression: acute tubular necrosis secondary to prolonged hypotension.”

  • Code: N17.0 (ATN)
    • A41.9 (sepsis, if unspecified organism)
    • R65.21 (severe sepsis with septic shock), etc.
  • Rationale: AKI documented and specifically labeled ATN → N17.0.

✅ Example 2 - Contrast-Induced ATN

“Patient with CAD underwent CT angiography with IV contrast. Two days later creatinine increased from 0.9 to 3.2, oliguria present. Assessment: contrast-induced acute tubular necrosis.”

  • Code: N17.0
    • T82/T85 or drug-related T36-T50 code if provider attributes as adverse effect of contrast (per note).
  • Rationale: Specific cause (contrast) and specific type (ATN) both documented.

✅ Example 3 - Rhabdomyolysis-Associated ATN

“Rhabdomyolysis after prolonged immobilization. Creatinine 5.0 mg/dL, oliguric, myoglobinuria. Nephrology: AKI due to acute tubular necrosis from rhabdomyolysis.”

  • Code: N17.0
    • M62.82 (rhabdomyolysis)
  • Rationale: ATN explicitly stated as mechanism of AKI.

❌ Example 4 - AKI but NO Tubular Necrosis Documented

“Acute kidney injury due to dehydration. Creatinine 2.1 from baseline 0.9, improved after IV fluids. No ATN mentioned.”

  • Correct: N17.9 (AKI, unspecified) + E86.0 (dehydration).
  • NOT N17.0 because tubular necrosis not documented.

Quick Coding Checklist for N17.0

Before assigning N17.0, confirm:

  • Provider wrote “AKI,” “acute renal failure,” or “acute kidney failure”.
  • Provider also wrote “acute tubular necrosis,” “ATN,” or “renal tubular necrosis.”
  • Onset is acute (hours-days), not chronic CKD only.
  • No documentation pointing to cortical or medullary necrosis instead (would be N17.1 or N17.2).
  • Associated condition(s) (sepsis, shock, dehydration, drugs, rhabdo, etc.) are coded.
  • If CKD also present, N18.x is coded in addition, not instead.
  • Traumatic or post-procedural etiologies have been ruled out or coded appropriately (S37.0-, N99.0, etc.).

Quick Reference Card (Copy Block)

ICD-10-CM N17.0 - Acute Kidney Failure with Tubular Necrosis
━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━━
USE WHEN:
-  Provider documents BOTH “AKI/acute renal failure” AND 
  “acute tubular necrosis / ATN / renal tubular necrosis”
-  Acute rise in creatinine + oliguria/anuria support AKI
-  Cause is intrinsic (ischemic or nephrotoxic tubular injury)
 
DO NOT USE WHEN:
-  Only “AKI” is documented → use N17.9
-  Cortical or medullary necrosis is specified → N17.1 or N17.2
-  Renal failure is traumatic or post-procedural → use injury/post-procedural codes
-  Kidney disease is chronic only (CKD) without acute component → N18.x only
 
RISK & PAYMENT:
-  Maps to HCC 135 (Acute Renal Failure) - high-risk condition
-  Drives Renal Failure DRGs (682-684) depending on MCC/CC
-  Supports intensive interventions (dialysis, ICU care, frequent labs)
 
BOTTOM LINE:
N17.0 is the **specific ATN code**. 
Any time “acute tubular necrosis (ATN)” is written, 
code **N17.0** - not N17.9.

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