Renal/Genitourinary - Step UP Flashcards
(170 cards)
definition of acute kidney injury
rapid decline in renal function with an increase in serum BUN or Cr (relative = 50% or absolute increase of 0.5-1.0 mg/dL)
MC clinical findings in AKI
weight gain and edema - due to positive water and Na+ balance
azotemia
elevated BUN and Cr
causes of elevated BUN
catabolic drugs (steroids) GI/Soft tissue bleeding dietary protein intake
BUN may be falsely low in..
liver disease
SIADH
malnutrition
etiology of prerenal AKI (7)
decrease in systemic arterial blood volume or renal perfusion
- hypovolemia
- CHF
- hypotension, 3rd spacing
- renal arterial obstruction
- cirrhosis/hepatorenal syndrome
- NSAIDs, ACE i and cyclosporin
- low albumin states
prerenal failure:
- urine osmolarity (1)
- urine Na+ (2)
- FE-Na+ (3)
- urine sediment (4)
- BUN/Cr ratio (5)
- urine-plasma Cr ratio (6)
(1) Uosm > 500; s.g. > 1.010 (concentrated)
(2) UNa < 20
(3) FENa < 1%
(4) hyaline casts; scant sediment
(5) BUN/Cr > 20:1
(6) urine-plasma Cr > 40:1
pt presents with muscle pain, weakness and dark urine - what should you suspect?
rhabdomyolysis
what can cause rhabdomyolysis?
trauma/crush injuries prolonged immobilities seizures snake bites drugs - cocaine alcohol infections
lab findings in rhabdomyolysis
elevated CPK (usually > 100, 000) hyperkalemia myoglobinuria (positive dipstick w/o RBCs) hypocalcemia hyperuricemia
Tx of rhabdomyolysis
IV fluids - maintain urine output of > 300 ml/hour until urine neg. for Myoglobin
Mannitol
Bicarbonate
intrinsic renal failure:
- BUN/Cr ratio (1)
- Urine Na (2)
- FE-Na (3)
- Urine osmolarity (4)
- urine plasma-Cr ratio (5)
- urine sediment (6)
(1) BUN/Cr < 20:1 (usually 10:1)
(2) Urine Na > 40
(3) FE-Na > 2-3%
(4) Uosm < 350
(5) urine plasma-Cr ratio < 20:1
(6) brown pigmented casts, epithelial casts
pt presents with envelope shaped crystals on UA with an increased AG metabolic acidosis - dx?
ethylene glycol poisoning
pt who recently underwent angioplasty develops renal failure and blue discoloration of fingers/toes - dx?
atheroembolic disease
- skin biopsy will show cholesterol crystals
how can you prevent contrast induced nephrotoxicity? (3)
hydration - 1-2L NS 12 hrs before
isotonic bicarbonate
N-acetylcysteine
three basic tests in post-renal failure
- physical examination - palpate bladder
- USG - obstruction, hydronephrosis
- catheter - large volume of urine ; residual volume > 50 ml
causes of post-renal failure
- BPH - MCC
- nephrolithiasis
- obstructing neoplasm
- retroperitoneal fibrosis
- neurogenic bladder
what kind of renal failure does a dipstick positive for protein suggest?
intrinsic renal failure due to glomerular insult
red cell casts
indicate glomerular disease - i.e. GN
broad waxy casts
chronic renal failure
muddy brown, granular casts
acute tubular necrosis
WBC casts
renal parenchymal inflammation
- pyelonephritis
- interstitial nephritis
fatty casts
nephrotic syndrome
formula for FE-Na
FEna = 100 x [Una x Pcr / Pna x Ucr]