Kidney Disorders
Acute Renal Failure
Distal RTA - Type I
Proximal RTA - Type II
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ACUTE RENAL FAILURE (ARF)
Urine findings in Prenal azotemia vs Acute Renal Failure
Prenal azotemia vs Acute renal failure:
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Specfic gravity >1.018 <1.012
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Urine osmolality > 300 - 500 < 300 - 400
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Urine Na (meq) < 20 meq/l > 40 meq/l
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Urine/plasma creatinine > 40 < 20
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Renal failure index (U Na/ U/P creat) < 1 >2
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Fractional excreation Na (U/P Na/ U/P creat)x100 <1 >2
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Response to fluid challenge ++ *Urine sediment normal, hyaline cast
brown granular casts, cellular debris
A. PRERENAL AZOTEMIA
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Hypovolemia: hemorrhage, GI fluid losses, diuretics, third spacing
(pancreatitis, peritonitis, burns, traumatized tissue)
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Heart failure: CHF, MI, pericardial tamponade, acute PE
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Peripheral vasodilatation: bacteremia, antihypertensive medications
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Increased renal vascular resistance: anesthesia, surgical operation,
hepatorenal syndrome.
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Renovascular obstruction, bilateral: thromboembolism
B. POSTRENAL AZOTEMIA
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Urethral/bladder obstruction: prostate enlargement, plugged Foley
catheter, stone, trauma, tumor(cancer), spasm, swelling (inflammation or
infection), neurogenic bladder (+/ ganglionic blocking agents)
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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.
C. RENAL DISORDERS/ AZOTEMIA
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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.
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Ischemic disorders
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Shock or hypotensive episodes: hypovolemia, hemorrhage, sepsis, cardiac
failure, neurogenic shock, third spacing, etc.
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Major trauma, crush syndrome, rhabdomyolysis, myoglobinuuria
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Transfusion reactions, hemolysis
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Major blood vessel disease: renal artery thromboembolism, stenosis,
bilateral renal vein thrombosis.
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Diseases of glomeruli & small blood vessels:
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Acute posotstreptococcal glomerulonephritis
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Idiopathic rapidly progressive glomerulonephritis
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Postpartum renal failure
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SLE glomerulonephritis
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Vasculitis: polyarteritis nodosa, Schonlein Henock ppurpura, Goodpasture's
syndrome, drug related vasculitis, serum sickness, subacute bacterial
endocarditis, hemolytic uremic syndrome
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Malignant hypertension
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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:
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Rx for fluid overload: fluid & salt restriction, diuretics, dialysis
or ultrafiltration.
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Rx for hyponatremia: water intake restriction
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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 !
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Rx for Metab. acidosis: restrict diet protein <40-60 g/d; NaHCO3,
Dialysis.
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Hypocalcemia Rx: CaCO3, or Ca-gluconate 10% 10-20 mL
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Hyperphosphatemia Rx: restrict diet phosphate intake, phosphate binding
agents (CaCO3, Al-OH)
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Hypermagnesemia Rx: avoid Mg++ containing antacids
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Hyperuricemia Rx: usually not needed if < 15 mg/dL
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Nutrition Rx: diet protein 0.5 g/kg/d, carbohydrate 100 g/d
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Drug dosage: adjust for degree of renal impairment.
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Dialysis for intractable fluid overload, hyperkalemia, metab. acidosis,
& uremic symptoms & signs.
(REF: Harrison's Med Text 1994)
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