Understanding Acute Tubular Necrosis
A Guide to Acute Tubular Necrosis
Explore the causes, symptoms, and treatment options for Acute Tubular Necrosis, a critical condition affecting kidney function.
What is Acute Tubular Necrosis?
Defining Acute Tubular Necrosis
Acute Tubular Necrosis (ATN) involves the death of tubular epithelial cells that form the renal tubules. The etiology is intrarenal, resulting from prolonged or severe ischemia.
Common causes of ATN include hypotension, sepsis, and use of nephrotoxic drugs (statins, cytotoxic drugs, ethylene glycol, NSAIDS, etc.).
ATN is one of the most common causes of AKI.
Diagnostic Criteria
- Meets criteria for AKI, creatinine levels return to baseline after > 3 days of treatment with IV fluids, urine sodium concentration > 40 mEq/L (normal < 20 mEq/L).
- Generally, urinalysis will show muddy brown casts, but absence of casts does not rule out ATN.
- ATN is suspected when AKI is diagnosed after an apparent contributing event i.e., contrast administration.
- Observed in about 45% of ICU patients and mortality rate as high as 62%.
- If the cause of the AKI is prerenal, it will usually respond to IV fluids quickly if it is ATN there may not be a noticeable improvement.
- For ATN, the treatment is supportive and aimed at the cause.
- For otherwise healthy patients, the serum creatinine generally returns to normal in 1 to 3 weeks.
Coding Considerations
- ATN code N17.0; instructional note: “code also” associated underlying condition
- Inclusion terms:
- Acute tubular necrosis
- Renal tubular necrosis
- Tubular necrosis
- Vasomotor Nephropathy
- NOS
- Excludes 1:
- Post-traumatic renal failure, T79.5 should not be reported with codes from code category N17
- Review the associated Coding Clinics:
- AHA Coding Clinic, Third Quarter 2024, p. 15
- AHA Coding Clinic, Fourth Quarter 2022, p. 33
- AHA Coding Clinic, Third Quarter 2020, p. 22
- Inclusion terms:
CDI Practice Considerations
- ATN (N17.0) is recognized as a Major Comorbidity (MCC) whereas AKI (N17.9) is a Complication/Comorbidity (CC).
- ATN is commonly under-diagnosed and under-documented, creating frequent query opportunity.
- The distinction between prerenal AKI and ATN is based on the clinical circumstances leading to AKI and the speed of the creatinine response to IV fluids.
- Providers may document Contrast Induced Nephropathy (CIN) in patients with contract induced AKI thinking it also includes ATN.
- CIN codes to N14.1 and does not provide a CC or MCC.
- When CIN is documented, review clinical indicators for diagnostic support and query as needed to clarify AKI due to ATN
- ATN may lead to electrolyte abnormalities such as hyperkalemia and hyponatremia.
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The information and opinions presented here are based on the experience, training, and interpretation of the author. Although the information has been researched and reviewed for accuracy, e4health does not accept any responsibility or liability regarding errors, omission, misuse, or misinterpretation. This information is intended as a guide; it should not be considered a legal/consulting opinion or advice.