From the Research
The initial workup for a patient suspected of having Acute Tubular Necrosis (ATN) should include a comprehensive assessment of renal function, urinalysis, and identification of potential causes, with a focus on recent exposures to nephrotoxic medications, hypotensive episodes, or major surgeries, as evidenced by studies such as 1. The workup should begin with a thorough history and physical examination.
- Laboratory tests should include serum creatinine, blood urea nitrogen (BUN), electrolytes, complete blood count, and urinalysis with microscopy.
- Urinalysis typically reveals muddy brown granular casts, renal tubular epithelial cells, and mild proteinuria in ATN.
- Calculate the fractional excretion of sodium (FENa), which is usually >2% in established ATN, distinguishing it from prerenal causes, as noted in 2.
- Renal ultrasound should be performed to rule out obstruction and assess kidney size and echogenicity. Additional tests may include:
- Urine osmolality
- Urine sodium concentration
- Urine-to-plasma creatinine ratio
- Biomarkers like neutrophil gelatinase-associated lipocalin (NGAL) or kidney injury molecule-1 (KIM-1) for early detection, as discussed in 3. These investigations help establish the diagnosis of ATN, differentiate it from other causes of acute kidney injury, and guide management decisions including fluid resuscitation, discontinuation of nephrotoxic agents, and consideration of renal replacement therapy if necessary, with the goal of reducing morbidity, mortality, and improving quality of life, as emphasized in 4 and 5.