ACUTE  RENAL  FAILURE

 

Etiology:

Increase of BUN/Cr. over hours to weeks and classified as :

  1. Prerenal- hypovolemia (dehydration, hemorrhage, hypotension, vasodilation, renal artery     stenosis, aortic dissection, sepsis, diuretics).
     
  2. Renal - tubuloglomerular (ATN, glomerulonephritis, rhabdo, NSAIDs, renal artery thrombosis, contrast material, meds)
     
  3. Postrenal - obstruction (BPH, mass obstructing urethras).

S & S:

  1. May present with anuria, oliguria or normouria.
     
  2. Uremic state (AMS), Met. Acidosis, Pulmonary edema,  Arrhythmias (2ry to  K).

DX:

  1. BUN/Cr., EKG, CBC, Ca, CPK,  UA, Cxray, ECHO/TEE (prn), US (prn).
     
  2. We can also identify renal failure into prerenal, renal and postrenal by following method: 


     

    PRERENAL

    RENAL

    POSTRENAL

    U Na

    <20mEq/L

    >40mEq/L

    20-40mEq/L

    U SG

    >1.020

    <1.010

    <1.010

    Bun/Cr

    >20:1

    =10:1

    <10:1

    FENa

    <1%

    >2%

    >2%








    *FENa = U Na / S Na    x 100
                            U Cr / S Cr

Legend: U = urine, SG = specific gravity, FENa = fractional  excretion of  Na.

Treatment:

  1. Prerenal - IVF, renal dose dopamine, R/O CV catastrophes if indicated.
     
  2. Renal - IVF, diuretics., dialysis (prn), alkalinization of urine with IV NaHCO3 1-2 amps in case  of  myoglobinuria.
     
  3. Postrenal - Foley cath, GU consult (prn)              

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