Acute Tubular Necrosis

A 42-year-old woman is admitted with acute kidney injury following rhabdomyolysis from a crush injury. Serum myoglobin is elevated, and urinalysis shows dark brown urine with positive dipstick for blood but no RBCs on microscopy. Which investigation is most appropriate to confirm myoglobin-induced acute tubular necrosis and assess severity?

A 58-year-old man with diabetes mellitus presents with acute kidney injury following sepsis from a urinary tract infection. Serum creatinine has risen from 1.2 to 4.8 mg/dL over 48 hours. Urine output is 200 mL/24 hours. Urinalysis shows muddy brown casts and fractional excretion of sodium (FENa) is 3.2%. Which investigation is most specific for confirming the diagnosis of acute tubular necrosis?

A 42-year-old woman with severe sepsis secondary to urosepsis is admitted to the ICU. She develops acute kidney injury with serum creatinine 3.8 mg/dL, oliguria (urine output 150 mL/24 h), and muddy brown casts on urinalysis. FENa is 3.2%. She is hypotensive (BP 88/52 mmHg) despite 2 L of crystalloid resuscitation. Blood cultures are pending. What is the first-line pharmacological agent to improve renal perfusion in sepsis-induced acute tubular necrosis?

A 58-year-old man with diabetes mellitus presents with acute kidney injury following a contrast-enhanced CT angiography for suspected pulmonary embolism. His urine microscopy shows muddy brown casts and granular casts. Which histopathological feature best distinguishes acute tubular necrosis (ATN) from acute interstitial nephritis (AIN)?

A 42-year-old woman with severe sepsis from urosepsis is admitted to the ICU. She has been oliguric (urine output 0.3 mL/kg/hr) for 18 hours despite aggressive fluid resuscitation. Serum creatinine has risen from 1.2 to 4.1 mg/dL. Urinalysis shows muddy brown casts, and fractional excretion of sodium (FENa) is 3.2%. Serum potassium is 6.8 mEq/L. What is the most appropriate next step in management?