Caster- Approach to AKI Flashcards
Does Cr clearance over- or under-estimate GFR? by how much? and why?
it over estimates it by 10-15% because that much is secreted by the PCT
Cr is derived from what?
mtb of creatine in skeletal muscle
What is required for accurate Cr level measurement
steady state
Cr level depends on what 3 things?
Age,
Muscle Mass/weight,
Gender
Cr levels are higher in what race
AA
The most dangerous/extreme changes in kidney function occur when Cr increases from what to what?
1-2
What is normal serum level for Cr?
0.6 - 1.2
define AKI
decline in renal function that occurs over hours-days
serum Cr increase 1–> 2 represents what % decrease in GFR?
50%
serum Cr increase 2 –> 3 represents what % decrease in GFR?
17%
What 4 tyhings are you unable to do in AKI
- excrete waste
- regulate volume
- Manage electrolytes
- make bicarb
What is stage one of AKIN criteria designed to catch and how
it catches early changes in kidney function by being the stage that occurs if sCr increases >0.3mg/dl
both RIFLE and AKIN criteria for AKI measure what two criteria (either of which can be used)
Serum Cr or Urine Output can be used
4 risk factors for AKI
CKD
DM
Heart or Liver dysfunction
Age >50
define azotemia
increased BUN and Cr
3 presenting things with AKI
Azotemia
Oliguria
Electrolyte Imbalance
define Oliguria
< 400 ml/day
define Anuria
< 50 ml/day
3 major causes of AKI
pre-renal
intra-renal
post-renal
What are the four intra-renal locations of AKI
tubular
Interstitial
GLomerular
Vascular
What are 2 indications for doing a renal biopsy on AKI pt?
1) Acute glomerulonephritis suspected (proteinuria, hematuria, RBC casts)
2) If etiology of AKI unclear or recovery is not as expected
Urinalysis shows muddy brown casts = what dx?
ATN
pre-renal AKI is caused by hypoperfusion cuased by what two things?
hypovolemia- (improves with fluids)
Decreased effective BV
What 3 conditions cuase decreased effective BV?
CHF
Cirrhosis
Sepsis
Inresponse to decreased BF kidneys do what 2 things to increase GFR?
release PGs to dilate AA
ATII vasoconstricts the EA (more than AA)
what 2 drug classes block ATII activity?
ACEIs, ARBs
What drug class blocks PG production–> AA vasoconstriction
NSAIDs
Pre-renal AKI BUN:cr ratio value and MOA
> 15
MOA: decreased GFR –> RAAS –> Na/H20 reabsorption and BUN follows
Urine Na in pre-renal AKI
low (<20)
Fractional excretion of Na (FeNa) in pre-renal AKI
<1%
Urine osm in pre-renal AKI and MOA
high (>500)
low GFR–> upregulated ADH –> concentrated urine
FeNa <1% = what dx
FeNa >2% = what dx
<1% = pre-renal AKI >2% = Intra-renal AKI (usually ATN or obstruction)
When do you use FeUrea instead of FeNa and why
if pt is on diuretics (since they impair Na reabsorption)
FeUrea <35% –> what dx
Pre-renal AKI
FeNa= equation FeUrea = equation
[(uNa)x(sCr)/(sNa)x(uCr)] x 100
[(sCr)x(uUrea)/(sUrea)x(uCr)] x 100
What is MC AKI in hospital
ATN
3 stages of ATN
Initisaition
Maintenance
Recovery
What causes muddy brown casts in ATN
necrotic tubule cells slough off into tubule
2 etiologies of ATN
ischemic
nephrotoxic
prolonged hypoperfusion destroys which 2 parts of tubule and why those?
PCT, TAL bc they are the most metabolically active
Nephrotoxic destroys which part of tubule
PCT
which mtbolite of ethylene glycol forms a stone and which type of stone in nephrotixic ATN
oxalate is a mtbolite
forms calcium oxalate stones
Pigment Nephropathy is due to what two proteins? what type of proteins are these?
Heme proitiens:
Myoglobin (muscle injury),
Hemoglobin (Hemolysis)
Two etiologies of Interstitial AKI
Pyelonephritis
AIN
What causes AIN
Drug -induced HSR in the interstitium and tubules
what are 4-drug causes of AIN
NSAIDs, Penicillin, diuretics, PPIs
Presentation of AIN ( 3 things- plus 1 finding which is the hallmark!!!???)
Fever, rash, pyuria/hematuira
Eosinophils in interstitium/urine = Hallmark!!!!
What 3 vascular TMAs cause interstitial AKI
Hemolytic Uremic Syndrome (HUS)
Thrombotic Thrombocytopenic Purpura (TTP)
Malignant HTN
common cause of AKI in children
Hemolytic Uremic Syndrome (HUS)
Cancer can cause what type of AKI
obstructive/post-renal
What is MC stone in adults
Calcium oxalate
What are urine findings (pH, smell) in Magnesium Ammonium phosphate (MAP) stones?
smells like Ammonia
Alkaline urine
Proteus causes what type os stone and what specific named calculus type
causes Magnesium Ammonium phosphate (MAP) stone with a “staghorn calculus”
AKI, AGMA, calcium oxalate stones = what dx
ethylene glycol ingestion
staghorn calculus, signs of infx (urine WBCs), alkaline urine–> what dx
proteus infx
Radiopaque (visible on XR) = what type of stones
calcium stones
Post-obstructive diuresis: MOA, complication of what?
accumulation of solutes –> osmotic diuresis
complicationo of bladder decompression after Stone removal
Indictaions for hemodialysis (5)= mnemonic and the thing itself
AEIOU
Acidosis (metabolic) - refractory
Electrolyte imbalance: hyperK, hyperCa, HypoNa
Ingestion: ehtylene glycol, methanol, lithium
Overload: refractory to diurectics
Uremia: BUN >100, sx (AMS, tremors)
if RBC cast is seen = dx
Glomerulonephritis
eosinophils in urine = dx
AIN
WBC cast = 2 dx
AIN, pyelonephritis
fatty cast or proteinuria = dx
nephrotic synd
