Acute Tubular Necrosis (ATN)

Exam Cram

• Acute tubular necrosis (ATN) describes a histological process which is a leading cause of renal AKI, particularly occurring with sepsis

• Diagnosis: AKI + high urine sodium > 40

• Pre-renal AKI results in a urinary sodium < 20

• Management: Renal Replacement Therapy 

Renal Reg Notes

Background

• Urine sodium is low in pre-renal disease < 20mmol to conserve fluid

• In ATN: urinary sodium > 40-50, relating to tubular injury

• Fraction excretion of sodium is a more accurate method for assessing urine sodium

High risk events for ATN to occur: 

• Shock: cardiogenic, haemorrhagic, hypovolaemia

• Sepsis

• Pancreatitis

• Severe burns

• Major surgery

Assessment

History

Examination

Investigations

• Raised urinary sodium

• Muddy brown urine casts

Diagnosis

Diagnostic criteria: clinical- acute AKI + raised urinary sodium, biopsy rarely done (gold standard)

Classification (aetiology)

• Ischaemia 

• Nephrotoxic drugs

• Ethylene glycol

• Lead, mercury

• Tenofovir

• Vancomycin (+- AIN)

Management

Acute

• Fluid balance

• Stop nephrotoxic drugs

• Renal Replacement Therapy as required

Inotropes and duiretics not shown to be of benefit in ATN

Prevention

• IVF balance

• Stop DAMN drugs: diuretics, ACEi, metformin, NSAIDs

Resources and References

1. Hanif MO, Bali A, Ramphul K. Acute Renal Tubular Necrosis. [Updated 2023 Jul 4]. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2025 Jan-. Available from: https://www.ncbi.nlm.nih.gov/books/NBK507815/

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Written in 2025