What is acute tubular necrosis (ATN)?

From the Guidelines

Acute tubular necrosis (ATN) is a form of acute kidney injury characterized by damage to the tubular cells of the kidneys, resulting in their death and dysfunction, and is typically caused by ischemia, nephrotoxicity, or sepsis, as outlined in the 2021 study by the Journal of the American College of Radiology 1. The pathophysiology of ATN involves damage to the tubular cells, which can occur due to various mechanisms, including reduced blood flow, exposure to toxins, or inflammatory responses.

• Ischemic ATN occurs when there is a reduction in blood flow to the kidneys, which can be caused by severe hypotension, major surgery, or hemorrhage.
• Nephrotoxic ATN results from direct cellular damage by substances like certain antibiotics, contrast media, chemotherapeutic agents, or heavy metals, as noted in the study by the Journal of the American College of Radiology 1.
• Sepsis-related ATN is caused by inflammatory mediators and endotoxins that lead to microvascular dysfunction and direct tubular injury. The clinical manifestations of ATN include oliguria or non-oliguric renal failure, elevated blood urea nitrogen and creatinine levels, and electrolyte imbalances, as discussed in the 2013 commentary by the Canadian Society of Nephrology 1. The treatment of ATN focuses on removing the underlying cause, maintaining fluid and electrolyte balance, avoiding further nephrotoxic exposures, and providing supportive care until the tubular cells regenerate, which typically occurs within 1-3 weeks if the injury is not too severe, as suggested by the study by the Journal of the American College of Radiology 1. In terms of management, the KDIGO AKI guideline suggests a stage-based management scheme with specific considerations for each stage, including the consideration of renal replacement therapy initiation and intensive care unit admission, as noted in the 2013 commentary by the Canadian Society of Nephrology 1. Overall, ATN is a serious condition that requires prompt recognition and treatment to prevent long-term kidney damage and improve patient outcomes, as emphasized in the study by the Journal of the American College of Radiology 1.

From the Research

Definition and Causes of Acute Tubular Necrosis

• Acute tubular necrosis (ATN) is a common cause of acute kidney injury (AKI) in adults, resulting from ischemia and/or tubular toxicity 2.
• The condition is characterized by desquamation of tubular epithelial cells and hyaline intra-tubular deposits 2.
• ATN can occur in hospitalized patients, particularly in the intensive care unit, with a mortality rate of 50% to 80% 3.

Diagnosis and Clinical Presentation

• Early diagnosis of ATN can be made by exclusion of prerenal and postrenal causes of acute renal failure, examination of urinary sediment, and analysis of urine measures such as fractional excretion of sodium in the absence of diuretics 3.
• AKI due to ATN 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.
• The association of an evocative clinical context and a spontaneous improvement of the AKI can confirm the diagnosis of acute tubular necrosis 2.

Treatment and Prognosis

• There is no specific treatment for ATN, but early involvement of nephrologists and supportive care can improve survival 3.
• Enteral rather than parenteral hyperalimentation in severely malnourished patients may improve survival 3.
• More aggressive dialysis with biocompatible membranes may improve survival in some patients with acute renal failure 3.
• The prognosis of ATN is often severe, and despite functional recovery, the cellular repair is abnormal, leading to accelerated renal aging and increased susceptibility to nephrotoxicity 2.
• Regular monitoring of renal function and simple nephroprotection measures are recommended for patients who have recovered from ATN to prevent chronic kidney disease 2.
• The majority of critically ill patients with normal renal function prior to the renal insults will recover sufficient renal function if they survive the precipitating cause of ATN 4.