Acute renal failure ARF

• History / PE:
  Prerenal ARF (decreased renal perfusion)
  Thirst, orthostatic hypotension , tachycardia, dry mucous membranes
  FeNa < 1%, UNa < 20, urine specific gravity > 1.020
  BUN/Cr > 20
  
  Intrinsic ARF (injury within nephron unit)
  History of drug exposure ( aminoglycosides , NSAIDs ), infection, or exposure to contrast media or toxins (eg. myoglobin, myeloma protein)
  Hematuria or tea-colored urine, foamy urine, HTN, edema
  
  Postrenal ARF (urinary outflow obstruction)
  Prostatic disease, decreased urine output leading to suprapubic pain, distended bladder and flank pain
• Treatment:
  Foley insertion
  Hemodialysis (if indicated)
• Complications:
  Chronic kidney disease
  CHF and pulmonary edema (volume overload)
• Pneumonic:
  Indications for urgent dialysis (" A E I O U ")
  
  A cidosis
  E lectrolyte abnormalities ( hyperkalemia )
  
  I ngestions (salicylates, theophylline , methanol, barbiturates, lithium , ethylene glycol)
  
  O verload (fluid)
  U remic symptoms ( pericarditis , encephalopathy, bleeding, nausea, pruritis, myoclonus)
• Notes:
  Both kidneys need to be out before see a significant rise in creatinine or BUN
  
  Patients with ARF may have normal urine volume (oliguria defined as < 500 cc/day)
• Differential Diagnosis:
  Prerenal ARF
  Hypovolemia (hemorrhage, burn, dehydration)
  Cardiogenic shock
  Systemic vasodilation
  Anaphylaxis
  Drugs (ACEIs, ARBs, NSAIDs )
  Renal artery stenosis
  Cirrhosis with ascites ( hepatorenal syndrome )
  
  Intrinsic ARF
  Acute tubular necrosis
  Acute/allergic interstitial nephritis
  Glomerulonephritis
  Thromboembolism
  Renovascular disease ( scleroderma , HUS/TTP)
  
  Postrenal ARF
  Prostatic disease
  Nephrolithiasis
  Pelvic tumors
  Recent pelvic surgery
  Retroperitoneal fibrosis