AKI ICD 10 refers to the International Classification of Diseases, Tenth Revision codes used to document Acute Kidney Injury (AKI) in clinical care and medical billing. AKI is a sudden decline in kidney function occurring over hours to days, leading to impaired waste elimination, electrolyte imbalance, and fluid dysregulation. Accurate ICD 10 coding is critical for patient safety tracking, clinical communication, reimbursement accuracy, and epidemiological reporting.
In the United States, AKI is common among hospitalized patients, particularly in intensive care units. Coding errors can result in claim denials, inaccurate severity adjustment, and distorted quality metrics. Understanding AKI ICD 10 codes requires clinical knowledge of AKI stages, causes, and diagnostic criteria.
What Is Acute Kidney Injury (AKI)?
Clinical Definition
Acute Kidney Injury is defined as a rapid reduction in kidney function resulting in:
- Rising serum creatinine
- Reduced urine output (oliguria or anuria)
- Inability to maintain fluid, electrolyte, and acid–base balance
AKI is not a single disease but a clinical syndrome with multiple causes.
How AKI Differs From CKD
| Feature | AKI | CKD |
|---|---|---|
| Onset | Sudden (hours–days) | Gradual (months–years) |
| Reversibility | Often reversible | Usually irreversible |
| ICD Coding | N17 series | N18 series |
AKI ICD 10 Code Overview
Primary AKI ICD 10 Code Category
N17 – Acute kidney failure
This category is used when AKI is newly developed and not chronic.
Complete AKI ICD 10 Code List
| ICD 10 Code | Description |
|---|---|
| N17.0 | Acute kidney failure with tubular necrosis |
| N17.1 | Acute kidney failure with acute cortical necrosis |
| N17.2 | Acute kidney failure with medullary necrosis |
| N17.8 | Other acute kidney failure |
| N17.9 | Acute kidney failure, unspecified |
N17.9 is the most commonly used code when documentation lacks etiology.
ICD 10 Coding Based on AKI Etiology
Prerenal AKI
Caused by reduced renal perfusion without intrinsic kidney damage.
- Dehydration
- Hemorrhage
- Heart failure
- Sepsis
Coding Tip: Often coded as N17.9 unless ischemic necrosis is documented.
Intrinsic (Intrinsic Renal) AKI
Results from direct kidney tissue injury.
Examples and Codes:
- Acute tubular necrosis → N17.0
- Cortical necrosis → N17.1
- Medullary necrosis → N17.2
Postrenal AKI
Caused by urinary tract obstruction.
- Prostate enlargement
- Kidney stones
- Ureteral obstruction
Coding Rule: AKI code plus obstruction code if documented.
Diagnostic Criteria Supporting AKI ICD 10 Coding
KDIGO Diagnostic Standards
AKI diagnosis requires at least one:
- Increase in serum creatinine ≥0.3 mg/dL within 48 hours
- Increase to ≥1.5 times baseline within 7 days
- Urine output <0.5 mL/kg/hr for 6 hours
Documentation must reflect these criteria to justify ICD 10 coding.
AKI Staging and Its Coding Implications
KDIGO Stages
| Stage | Creatinine Change | Urine Output |
|---|---|---|
| Stage 1 | 1.5–1.9× baseline | <0.5 mL/kg/hr (6–12h) |
| Stage 2 | 2.0–2.9× baseline | <0.5 mL/kg/hr ≥12h |
| Stage 3 | ≥3.0× baseline or dialysis | <0.3 mL/kg/hr ≥24h |
Important: ICD 10 does not have stage-specific AKI codes. Severity must be inferred from clinical documentation.
AKI ICD 10 in Hospital Billing and DRG Impact
AKI is a Complication or Comorbidity (CC) and sometimes a Major CC (MCC) depending on severity and treatment.
Billing Impact
- Increases MS-DRG weight
- Affects hospital reimbursement
- Influences risk-adjusted mortality metrics
Incorrect coding may lead to audits or revenue loss.
Documentation Best Practices for AKI ICD 10
Required Provider Documentation
- Explicit diagnosis of “acute kidney injury” or “acute renal failure”
- Identified cause if known
- Supporting labs or clinical findings
- Treatment actions (IV fluids, dialysis, medication adjustment)
Common Documentation Errors
- Using “renal insufficiency” without defining acuity
- Missing baseline creatinine
- Failure to clarify AKI vs CKD vs AKI on CKD
AKI on Chronic Kidney Disease (AKI on CKD)
When AKI occurs in a patient with pre-existing CKD:
Coding Rules:
- Code AKI first (N17.x)
- Then code CKD (N18.x)
Example:
- N17.9 – Acute kidney failure, unspecified
- N18.3 – CKD stage 3
Unique Clinical Takeaways
1. Patient Experience and Delayed AKI Recognition
Many patients do not experience pain or early symptoms during AKI. Fatigue or reduced urine output is often overlooked. Delayed recognition increases progression risk. Clinicians should consider AKI in elderly patients after contrast imaging or acute illness even with minimal symptoms.
2. Differential Diagnosis Pitfalls
AKI can be misclassified as dehydration or medication side effects. NSAIDs, ACE inhibitors, and diuretics frequently mask early AKI. Failure to discontinue nephrotoxic drugs can worsen kidney injury and affect outcomes.
3. Risk Stratification Beyond Labs
Patients with diabetes, heart failure, liver disease, or sepsis have disproportionately higher AKI mortality even with modest creatinine rises. Risk assessment should incorporate comorbid burden, not just lab thresholds, to guide early intervention.
Treatment Overview (Clinical Context)
Treatment depends on etiology:
- Volume resuscitation for prerenal AKI
- Removal of nephrotoxins
- Relief of obstruction
- Renal replacement therapy when indicated
Treatment details support medical necessity for coding audits.
Prognosis and Outcomes
- Many AKI cases are reversible
- Severe or recurrent AKI increases long-term CKD risk
- AKI survivors have higher cardiovascular morbidity
Accurate ICD 10 coding enables long-term outcome tracking.
AKI ICD 10 and Quality Reporting
AKI rates influence:
- Hospital quality scores
- ICU outcome benchmarks
- Public health surveillance
Underreporting distorts institutional performance data.
Medical Disclaimer
This content is for informational and educational purposes only and does not substitute professional medical advice, diagnosis, or treatment. Clinical decisions and coding practices must be based on official guidelines, provider judgment, and payer-specific policies