What is acute tubular necrosis (ATN)?

From the Guidelines

Acute tubular necrosis (ATN) is a serious kidney condition characterized by damage to the tubular cells of the nephrons, leading to acute kidney injury, and it is crucial to address the underlying cause and maintain fluid and electrolyte balance to prevent morbidity and mortality. ATN occurs when the tubular cells die due to lack of oxygen (ischemia) or exposure to toxins, such as certain medications (like aminoglycosides, NSAIDs, and contrast agents) 1. The most common causes of ATN include severe hypotension, sepsis, major surgery, and severe infections.

Causes and Risk Factors

ATN typically progresses through three phases: initiation (initial injury), maintenance (established kidney dysfunction), and recovery (gradual return of kidney function). Certain medications, such as cisplatin, ifosfamide, and pemetrexed, can cause ATN by inducing acute tubular injury and acute tubular necrosis 1. Other risk factors include pre-existing kidney disease, diabetes, and older age.

Symptoms and Diagnosis

Symptoms of ATN include decreased urine output (oliguria), fluid retention causing swelling, confusion, nausea, and fatigue. Diagnosis involves blood tests showing elevated creatinine and BUN levels, urinalysis revealing granular casts and renal tubular epithelial cells, and sometimes kidney imaging or biopsy 1. Urine biomarkers, such as neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule-1 (KIM-1), interleukin-18 (IL-18), and liver fatty acid-binding protein (L-FABP), can also help diagnose ATN 1.

Treatment and Prevention

Treatment focuses on addressing the underlying cause, maintaining fluid and electrolyte balance, and sometimes temporary dialysis. Most patients recover within 1-3 weeks with proper management, though some may develop chronic kidney disease. Prevention strategies include maintaining adequate hydration, avoiding nephrotoxic medications when possible, and careful monitoring of at-risk patients. Unfortunately, I cannot provide photos in this response, but microscopic examination would show damaged tubular cells, cellular debris in tubular lumens, and flattened epithelium during the recovery phase.

Key Points

• ATN is a serious kidney condition that requires prompt treatment to prevent morbidity and mortality.
• Certain medications and underlying medical conditions can increase the risk of ATN.
• Diagnosis involves blood tests, urinalysis, and sometimes kidney imaging or biopsy.
• Treatment focuses on addressing the underlying cause and maintaining fluid and electrolyte balance.
• Prevention strategies include maintaining adequate hydration and avoiding nephrotoxic medications when possible.

From the Research

Definition and Causes of Acute Tubular Necrosis

• Acute tubular necrosis (ATN) is a leading cause of acute kidney injury (AKI) in adults, characterized by desquamation of tubular epithelial cells and hyaline intra-tubular deposits secondary to ischemia and/or tubular toxicity 2.
• The condition is frequently observed with a non-altered urine output and associated with a proteinuria less than 1.5 g/24h without albuminuria, hematuria or leucocyturia 2.
• AKI is classified according to the RIFLE criteria, which determines the level of renal dysfunction based on changes from baseline serum creatinine or urine output 3.

Risk Factors and Outcomes

• The use of aminoglycosides (AGs) has been associated with an increased risk of AKI, particularly in patients with vancomycin coadministration, high AG trough levels, and heart failure 4, 5.
• Renal recovery occurs in approximately 50% of patients with AG-AKI, and is less likely with heart failure and higher AKI severity 4.
• Patients without prior chronic kidney disease (CKD) who receive AGs are at risk of AKI, especially those with low albumin or hemoglobin levels 5.

Epidemiology and Assessment

• The term acute kidney injury (AKI) has been proposed to encompass the entire spectrum of the syndrome from minor changes in renal function to requirement for renal replacement therapy 6.
• The RIFLE criteria provide a uniform definition of AKI and have been validated in numerous studies, with a population incidence of approximately 2000-3000 patients per million population per year 6.
• AKI is associated with increased mortality, even after correction for covariates, and patients with AKI who are treated with renal replacement therapy (RRT) still have a mortality of 50-60% 6.

Photos and Illustrations

• Unfortunately, no photos or illustrations are available in the provided text to demonstrate the characteristics of acute tubular necrosis.
• However, the condition can be illustrated by diagrams showing the normal and damaged renal tubules, as well as the effects of ischemia and toxicity on the kidney tissue.
• Images of kidney biopsies or ultrasound scans can also be used to demonstrate the changes in kidney structure and function associated with ATN.