an approach to evaluation and management of acute kidney disease

1. Acute renal failure
Acute kidney injury

2. ARF
 Sudden- <48 hours- decrease in renal
function
 Results in inability to excrete nitrogenous
waste & maintain fluid-electrolyte balance
 Present in-
 ~30% of ICU admissions
 ~5% of hospital admissions
 Develops in ~25% of in-patients
 Measured by rising serum creatinine

3. Classification
 Pre-renal- decreased renal perfusion- ~50%
 Renal- ~40-45%
 Acute tubular necrosis- ATN- ~80%
ischemic or toxic insult
 Acute interstitial nephritis- AIN- ~15%
mostly drug-induced inflammatory
response
 Acute glomerulonephritis- AGN- ~5%
immunological glomerular injury
 Post-renal- obstruction of B/L urinary tract,
increasing intraluminal pressure- ~5-10%

4. ARF- pre-renal
 Commonest cause of ARF
 Due to renal hypoperfusion, due to-
 Decreased intravascular volume- hemorrhage, diarrhea,
dehydration, pancreatitis, burns, diuresis
 Change in vascular resistance- shock, NSAIDs, ACEI,
vasopressors, cyclosporin, renal artery stenosis
 Low cardiac output- cardiogenic shock, CHF, PE,
pericardial tamponade
 Dx- clinical scenario & BUN/Cr ratio >20
 Rx- of underlying cause, fluid repletion

5. ARF- post-renal
 Due to obstruction of urinary flow, due
to-
 Urethral valve/stricture
 Bladder outlet obstruction- BPH, prostate/bladder ca.
 B/L ureteric obstruction- cervical cancer, stones, clots
 Dx- clinical scenario & ultrasound/CT
 Rx- relieve obstruction
 Beware of post-obstructive diuresis

6. ATN- proximal tubule
 Causes-
 Ischemia- surgery, trauma, rhabdomyolysis, prolonged hypoperfusion
 Nephrotoxins- aminoglycosides, radiocontrast, Amphotericin,
Vancomycin, Cyclosporin
 Dx- clinical scenario & urinanalysis-muddy granular cast,
hyperkalemia is common
 Rx- recovery heralded by diuresis
 Monitoring & supportive treatment
 Diuretics- loop ± thiazides
 Dialysis- hyperkalemia, fluid overload, acidosis, encephalopathy
 Px- better for non-oliguric patient &
worse for surgical illness

7. AIN
 Interstitial edema & inflammation
 Causes-
 Drugs- penicillins, cephalosporins, sulfonamides, NSAIDs
 Infections- streptococcal, leptospirosis, CMV, RMSF
 s/s- fever, rash, arthralgia
 Dx- eosinophilia & eosinophiluria, WBC casts
 Rx- remove inciting drug & supportive Rx,
steroids & dialysis in severe prolonged cases

8. AGN
Part of ‘Glomerulonephritis’