Caster- Approach to AKI Flashcards by Thomas Ems

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

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Cr is derived from what?

mtb of creatine in skeletal muscle

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What is required for accurate Cr level measurement

steady state

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Cr level depends on what 3 things?

Age,
Muscle Mass/weight,
Gender

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Cr levels are higher in what race

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The most dangerous/extreme changes in kidney function occur when Cr increases from what to what?

1-2

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What is normal serum level for Cr?

0.6 - 1.2

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define AKI

decline in renal function that occurs over hours-days

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serum Cr increase 1–> 2 represents what % decrease in GFR?

50%

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serum Cr increase 2 –> 3 represents what % decrease in GFR?

17%

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What 4 tyhings are you unable to do in AKI

excrete waste
regulate volume
Manage electrolytes
make bicarb

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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

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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

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4 risk factors for AKI

CKD
DM
Heart or Liver dysfunction
Age >50

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define azotemia

increased BUN and Cr

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3 presenting things with AKI

Azotemia
Oliguria
Electrolyte Imbalance

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define Oliguria

< 400 ml/day

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define Anuria

< 50 ml/day

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3 major causes of AKI

pre-renal
intra-renal
post-renal

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What are the four intra-renal locations of AKI

tubular
Interstitial
GLomerular
Vascular

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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

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Urinalysis shows muddy brown casts = what dx?

ATN

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pre-renal AKI is caused by hypoperfusion cuased by what two things?

hypovolemia- (improves with fluids)

Decreased effective BV

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What 3 conditions cuase decreased effective BV?

CHF
Cirrhosis
Sepsis

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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