Please enable JavaScript.

Coggle requires JavaScript to display documents.

ACUTE RENAL FAILURE (ARF) - Coggle Diagram

- - - - Early stage of obstruction→ ↑↑ tubular pressure "forces" BUN into the blood (serum BUN:Cr ratio> 15); tubular function remains intact (FENa < 1% and urine osm > 500 mOsm/kg)
        
        Long-standing obstruction→tubular damage →
        ↓reabsorption of BUN serum; BUN:Cr ratio< 15
        ↓decreased reabsorption of sodium; FENa > 2%
        inability to concentrate urine: urine osm < 500 mOsm/kg
- - - - Dysfunctional tubular epithelium→ ↓↓reabsorption of BUN
        
        Etiology:
        
        Nephrotoxic: Toxic agents →necrosis of tubules
        
        Proximal tubule is particularly susceptible
        
        Causes: MOST COMMON aminoglycosides, heavy metals (lead), myoglobinuria (from crush injury to muscle), ethylene glycol (associated with oxalate crystals in urine), radiocontrast dye, and urate (tumor lysis syndrome).
        
        Hydration and allopurinol are used prior to initiation of chemotherapy to decrease risk of urate-induced ATN.
        
        Ischemic: Decreased blood supply results in necrosis of tubules
        
        Preceded by prerenal azotemia
        
        Proximal tubule & medullary segment of the thick ascending limb are particularly susceptible to ischemic damage.
        
        Clinical features
        
        Oliguria + brown-granular casts
        
        ↑↑ BUN + ↑↑ creatinine
        
        Hyperkalemia (due to decreased renal excretion) + metabolic acidosis
        
        Reversible!! BUUUUT often requires supportive dialysis since electrolyte imbalances can be fatal; Oliguria for 2-3 weeks before recovery tubular cells (stable cells) take time to reenter the cell cycle and regenerate.
      - BUN:Cr ratio< 15
        FENa > 2%
        urine osm < 500 mOsm/kg
- - - - Reabsorption of fluid and BUN→ serum BUN:Cr ratio > 15
        
        Tubular function remains intact → fractional excretion of sodium FENa < 1% + urine osmolality [osm] > 500 mOsm/kg
- - - - Clinical: oliguria, fever, and rash days
        to weeks after starting a drug;
        eosinophils may be seen in urine.
        
        Resolves with cessation of drug
        
        May progress to renal papillary necrosis
- - - - Etiology:
        
        Chronic analgesic abuse (long-term phenacetin or aspirin)
        
        DM
        
        Sickle cell trait/disease
        
        Severe acute pyelonephritis