SIM - acute renal failure

Question 1

Acute vs. Chronic Renal Failure

Answer 1

acute –> less than a month, would see changes in hematocrit and creatinine

Question 2

Azotemia

Answer 2

elevated BUN and serum creatinine levels

Question 3

Prerenal failure

Answer 3

due to decreased blood flow to kidneys (heart failure)

• causes decreased GFR, azotemia, and oliguria
• resorption of fluid and BUN ensues and causes high BUN:Cr ratio (>15)
• tubular function remains intact

Question 4

Postrenal failure

Answer 4

due to obstruction of urinary tract flow (downstream from kidneys)

• causes decreased GFR, azotemia, oliguria
• EARLY = increased tubular forces –> increased BUN:Cr ratio
• LATE = tubular damage –> decreased BUN:Cr ratio and increased FENa (reduced sodium resorption)

Question 5

Acute Tubular Necrosis

Answer 5

due to injury and necrosis of tubular epithelial cells (most common cause of ARF)

• necrotic cells plug up tubules –> obstruction (decreased GFR) –> cells get sloughed off and result in oliguria with brown, granular casts in urine
• dysfunctional tubular epithelium causes decreased BUN:Cr ratio, increased FENa (reduced sodium resorption)
• can be ischemic or nephrotoxic etiology

Question 6

Acute Interstitial Nephritis

Answer 6

drug-induced hypersensitivity involving interstitium and tubules

• NSAIDs, penicillin, diuretics
• oliguria, fever, rash, eosinphilia in urine
• resolves with cessation of drug

Question 7

Key feature of NSAID induced interstitial nephritis

Answer 7

Rash, eosinophilia (40% of cases), hematuria (40% of cases), pyuria, eosinophiluria, proteinuria, renal failure (requiring dialysis in about 1/3 of cases), nephrotic syndrome