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Kidney Disorders

Acute Renal Failure

Distal RTA - Type I

Proximal RTA - Type II

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Urine findings in Prenal azotemia vs Acute Renal Failure
Prenal azotemia vs Acute renal failure:

  • Specfic gravity >1.018 <1.012
  • Urine osmolality > 300 - 500 < 300 - 400
  • Urine Na (meq) < 20 meq/l > 40 meq/l
  • Urine/plasma creatinine > 40 < 20
  • Renal failure index (U Na/ U/P creat) < 1 >2
  • Fractional excreation Na (U/P Na/ U/P creat)x100 <1 >2
  • Response to fluid challenge ++ *Urine sediment normal, hyaline cast brown granular casts, cellular debris


  1. Hypovolemia: hemorrhage, GI fluid losses, diuretics, third spacing (pancreatitis, peritonitis, burns, traumatized tissue)
  2. Heart failure: CHF, MI, pericardial tamponade, acute PE
  3. Peripheral vasodilatation: bacteremia, antihypertensive medications
  4. Increased renal vascular resistance: anesthesia, surgical operation, hepatorenal syndrome.
  5. Renovascular obstruction, bilateral: thromboembolism


  1. Urethral/bladder obstruction: prostate enlargement, plugged Foley catheter, stone, trauma, tumor(cancer), spasm, swelling (inflammation or infection), neurogenic bladder (+/ ganglionic blocking agents)
  2. Bilateral ureter obstruction a. Intraureteral: blood clots, sulfonamide & uric acid crystals, pyogenic debris, stones, edema, necrotizing papillitis. b. Extraureteral: tumor (cervix, prostate, endometriosis), periureteral fibrosis, accidental ureteral ligation during pelvic operation.


  1. Nephrotoxins, including hypersensitivity reactions
    a. Antibiotics: aminoglycosides, amphotericin B, vancomycin, sulfa
    b. X ray contrast media (esp. in DM)
    c. Heavy metals: mercury, lead, arsenic, bismuth, uranium, cadmium
    d. Ethylene glycol poisoning, carbon tetrachloride, other oranic solvents, pesticides, fungicides
    e. Other drugs & chemical agents: anesthetics (methoxyflurane) phenacetin, diphenylhydantoin, phenylbutazone, uric acids, calcium, poisonous mushroom, venom, etc.
  2. Ischemic disorders
    • Shock or hypotensive episodes: hypovolemia, hemorrhage, sepsis, cardiac failure, neurogenic shock, third spacing, etc.
    • Major trauma, crush syndrome, rhabdomyolysis, myoglobinuuria
    • Transfusion reactions, hemolysis
  3. Major blood vessel disease: renal artery thromboembolism, stenosis, bilateral renal vein thrombosis.
  4. Diseases of glomeruli & small blood vessels:
    • Acute posotstreptococcal glomerulonephritis
    • Idiopathic rapidly progressive glomerulonephritis
    • Postpartum renal failure
    • SLE glomerulonephritis
    • Vasculitis: polyarteritis nodosa, Schonlein Henock ppurpura, Goodpasture's syndrome, drug related vasculitis, serum sickness, subacute bacterial endocarditis, hemolytic uremic syndrome
    • Malignant hypertension
  5. Interstitial nephritis: a. Drugs b. Diffuse infection c. Hypercalcemia nephritis d. Postpartum renal failure e. SLE glomerulonephritis f . Vasculitis: polyarteritis nodosa

RX of the complications of intrinsic Acute Renal Failure:

  1. Rx for fluid overload: fluid & salt restriction, diuretics, dialysis or ultrafiltration.
  2. Rx for hyponatremia: water intake restriction
  3. Rx for hyperkalemia: K diet restriction, avoid K+ sparing diuretics, Kayexalate 30 g 3-4x/d PO + 100 mL 20% sorbitol to prevent constipation (or 30-50 g in 200 mL sorbitol rectal enema q6h), Ca-gluconate 10% 10 mL amp over 5 min (be careful if pt on digoxin), NaHCO3 7.5% 1-2 amp + insulin 10-15 u in 500 mL D5W over a couple hours; IV Furosemide 40-80 mg; Florinef (fludrocortisone 0.1-1 g/d.)
    *   Dialysis !
  4. Rx for Metab. acidosis: restrict diet protein <40-60 g/d; NaHCO3, Dialysis.
  5. Hypocalcemia Rx: CaCO3, or Ca-gluconate 10% 10-20 mL
  6. Hyperphosphatemia Rx: restrict diet phosphate intake, phosphate binding agents (CaCO3, Al-OH)
  7. Hypermagnesemia Rx: avoid Mg++ containing antacids
  8. Hyperuricemia Rx: usually not needed if < 15 mg/dL
  9. Nutrition Rx: diet protein 0.5 g/kg/d, carbohydrate 100 g/d
  10. Drug dosage: adjust for degree of renal impairment.
  11. Dialysis for intractable fluid overload, hyperkalemia, metab. acidosis, & uremic symptoms & signs.

(REF: Harrison's Med Text 1994)