Acute Kidney Injury Flashcards
7 cards from real Internal Medicine Exam practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.
Read the first 7 Acute Kidney Injury flashcards as text
A 68-year-old man with chronic heart failure presents with worsening dyspnea and oliguria. Creatinine has risen from 1.2 to 2.8 mg/dL after aggressive diuresis. Urine sodium is 8 mEq/L and BUN/Cr ratio is 28. What is the most likely mechanism of AKI?
Answer: Cardiorenal syndrome type 1
Cardiorenal syndrome type 1 occurs when acute cardiac decompensation causes AKI, with low urine sodium reflecting avid sodium retention due to reduced renal perfusion.
Which of the following urine microscopy findings is most specific for acute tubular necrosis?
Answer: Muddy brown granular casts
Muddy brown granular casts (composed of sloughed tubular epithelial cells) are the hallmark finding of acute tubular necrosis.
A patient develops AKI after receiving vancomycin. Urinalysis shows eosinophiluria and white blood cell casts. Serum creatinine peaks at 3.1 mg/dL on day 10. What is the primary pathophysiology?
Answer: Acute interstitial nephritis
Vancomycin-induced AKI commonly causes acute interstitial nephritis, characterized by eosinophiluria, WBC casts, and a delayed onset after drug exposure.
In the AKIN staging system, Stage 2 AKI is defined as:
Answer: Creatinine increase ≥2× baseline or urine output <0.5 mL/kg/h for 12 hours
AKIN Stage 2 is defined as serum creatinine increase ≥2× but <3× baseline, or urine output <0.5 mL/kg/h for ≥12 hours.
A 55-year-old woman with lupus presents with AKI, RBC casts, proteinuria >2 g/day, and hypertension. Which diagnosis best fits this presentation?
Answer: Lupus nephritis causing rapidly progressive glomerulonephritis
RBC casts, nephrotic-range proteinuria, and hypertension in a lupus patient indicate lupus nephritis with rapidly progressive glomerulonephritis as the cause of AKI.
Which medication most commonly causes AKI through renal afferent arteriolar vasoconstriction leading to decreased GFR?
Answer: NSAIDs
NSAIDs inhibit prostaglandin synthesis, impairing afferent arteriolar dilation that normally compensates in states of reduced renal perfusion, causing prerenal AKI.
A 72-year-old man with BPH presents with AKI and bilateral hydronephrosis on ultrasound. Bladder scan shows 800 mL of residual urine. After Foley catheter placement, urine output is 400 mL/hour. What electrolyte complication is most expected?
Answer: Post-obstructive diuresis causing hypokalemia and hyponatremia
Post-obstructive diuresis after relief of urinary obstruction commonly causes hypokalemia and hyponatremia due to loss of electrolytes in large urine volumes.