Renal/Genitourinary - Step UP Flashcards
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]
formula for renal failure index
(Una x Pcr) / Ucr
- > 1% = prerenal failure
- < 1% = ATN
MC mortal complications in early AKI
hyperkalemic cardiac arrest
pulmonary edema
metabolic complications in AKI
hyperkalemia metabolic AG acidosis hypocalcemia hyponatremia hyperphosphatemia hyperuricemia
how do you monitor fluid balance in AKI?
daily weight measurements - most accurate
input/output records
when should you order dialysis in AKI?
symptomatic uremia
intractable acidemia, hyperkalemia or volume overload develop
Tx. of prerenal AKI
eliminate any offending agents
give normal saline to restore BP
Tx. of intrinsic AKI
therapy is supportive
may try furosemide to increase urine output
Tx. of postrenal AKI
bladder catheter
urology consult
uremia
signs and symptoms associated with accumulation of nitrogenous waste due to impaired renal function; BUN > 60
signs and symptoms of uremia (8)
severe acidosis mental status changes hyperkalemia fluid overload anemia hypocalcemia pericarditis impaired cellular and humoral immunity
chronic renal insufficiency
renal function is compromised but not failed
serum Cr between 1.5-3.0 mg/dL
CV symptoms in CRF
HTN - secondary to salt and H20 retention
CHF
pericarditis - uremic
Neurologic findings in CRF
lethargy, confusion, somnolence, peripheral neuropathy, seizures
P/E findings - weakness, asterixis, hyperreflexia, “Restless legs”
Hematologic findings in CRF
- normochromic normocytic anemia (def. EPO) Tx. EPO replacement
- bleeding dysfunction - platelets cant degranulate in uremic envt (Tx. DDVAP)
endocrine disturbances in CRF
hyperphosphatemia –> decreased vit D production –> hypocalcemia –> elevated PTH –> renal osteodystrophy and eventually hyPERcalcemia
calciphylaxis
in high phosphate states, the phosphate may precipitate with calcium causing vascular calcifications and necrotic skin lesions
what drugs can slow the progression of ESRD?
ACEi - dilate efferent arteriole and control BP
diet in CRF
low protein - 0.7-0.8 g/kg body weight
restrict K+, phosphate and Mg2+ intake
how do you tx. hyperphosphatemia in CRF?
phosphate binders
- calcium citrate
- sevelamer/levanthum (esp. when due to vit D intake)
- cinacalcet (mimics effect of Ca2+ on PTH)
what type of replacement therapy should CRF pts be on?
long term oral Calcium and vit D
oral Bicarb if acidotic
when should you treat anemia with EPO?
if Hct < 30 or Hb < 10 mg/dl AFTER iron deficiency has been ruled out and pt w/ symptoms of anemia on dialysis
non-emergent indications for dialysis:
- symptoms of uremia i.e. NV, bleeding, lethargy, mental status changes, pericarditis
emergency indications for dialysis (5)
- pulmonary edema
- refractory HTN emergency
- refractory hyperkalemia, hypermagnesemia
- severe metabolic acidosis
- certain drug overdoses
which drugs are dialyzable?
Lithium
Salicylates
Ethylene glycol/Methanol
Mg2+ containing laxatives
“First use” syndrome in dialysis
chest pain, back pain and anaphylaxis (rare) occuring immediately after patient uses a new dialysis machine
complications associated with peritoneal dialysis
peritonitis - cloudy fluid
abdominal/inguinal hernia
hyperglycemia/hypertriglyceridemia
protein malnutrition
what should you do if you suspect orthostatic proteinuria in someone?
obtain daytime and nighttime urine samples
- decrease protein in night-time samples
what is orthostatic proteinuria associated with?
nutcracker syndrome - entrapment of Left renal vein b/w aorta and SMA
key features of nephrotic syndrome
proteinuria > 3.5 g/day hypoalbuminemia --> edema hyperlipidemia/lipiduria hypercoagulable state increased infections
initial test once proteinuria is detected on urine dipstick
urinalysis –> if UA confirms proteinuria, next step is 24 hr urine collection
how do you test for microalbuminuria?
special dipsticks can detect 30-300 mg/day of protein –> if these are positive, do a radioimmunoassay to confirm
most sensitive and specific test for microalbuminuria
radioimmunoassay
definition of proteinuria
> 150mg/24 hrs
definition hematuria
> 3 RBCs/hpf on urinalysis
- persistent if in > 2 samples
microscopic hematuria is more commonly (1) whereas, gross hematuria is more commonly (2)
(1) glomerular origin
(2) nonglomerular or urologic
in adults, gross hematuria is what? unless proven otherwise
malignancy - consider bladder cancer or renal cell carcinoma
what are the initial diagnostic tests in gross hematuria?
- upper urinary tract CT scan or IVP
2. endoscopic assessment of bladder and urethra
what medications can cause hematuria?
Rifampin cyclophosphamide anticoagulants salicylates sulfonamides analgesics
what do you do if you find RBC casts and dysmorphic RBCs on UA? what does this mean?
evaluate for intrinsic renal disease –> likely a glomerular cause
what does it mean if the dipstick if positive for blood but no RBCs can be seen under microscope?
hemoglobinuria or myoglobinuria is present
how do you approach hematuria if U/A and urine culture turn up negative?
- do a coag study - if +, coagulopath
- if negative proceed to 2) KUB
- if shows stones, tx stones
- if normal, do 3) IVP, CT scan and cytology
classic lab findings in nephritic syndrome
hematuria anuria/oliguria proteinuria < 3 g/day HTN edema
Tx. of nephrotic syndrome
1) steroids
2) if no effect: add cyclophosphamide or azathioprine
3) ARBs/ACEi can inhibit proteinuria
young child presents with nephrotic syndrome; you note fusion of foot processes on EM - dx? what is this dx associated with?
dx = minimal change disease
- assoc. with Hodgkins and NH lymphomas