Renal · AKI classification, prerenal/intrinsic/postrenal diagnosis, ATN, AIN, papillary necrosis, rhabdomyolysis
By completing this question set, you will be able to classify acute kidney injury as prerenal, intrinsic, or postrenal using a structured laboratory approach (BUN/Cr ratio, FENa, urine Na⁺, urine osmolality, urine sediment). You will calculate and interpret FENa, recognize its limitations, and know when to use FE-urea instead. You will diagnose specific intrinsic AKI causes by matching urine sediment to disease: muddy brown granular casts (ATN), WBC casts with eosinophiluria (AIN), and RBC casts (glomerulonephritis). You will distinguish ischemic from nephrotoxic ATN, describe the three phases of ATN recovery, and prevent contrast-induced nephropathy. You will identify acute interstitial nephritis from drug history and systemic features, recognize the NSAID exception to the AIN triad, and identify papillary necrosis from its clinical causes. You will diagnose rhabdomyolysis from its distinctive laboratory constellation and manage the resulting AKI.