Exam 3: Renal AKI Flashcards

1
Q

What is the very general definition of AKI

A

AKI:
An abrupt decline in renal function as measured in rise in BUN:creatinine ratio OR drop in urine output

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2
Q

KDIGO Definitions of AKI:
1. Increase in serum creatinine by ____ in 48 hours

OR

  1. Increase in serum creatinine to ____ times baseline, known or presumed to have occured in prior 7 days

OR

  1. Urine volume _____ for 6 hours
A

KDIGO Definitions of AKI:

  1. Increase in serum creatinine by > 0.3 mg/dL within 48 hours
  2. Increase in serum creatinine to >1.5 times baseline (presumed to have occured in past 7 days)
  3. Urine volume < 0.5 mL/kg/hr for 6 hours
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3
Q

CKD is defined as kidney damage or GFR of ______ for three months or more irrespective of cause

A

GFR is defined as kidney damage or GFR < 60 for three months or more irrespective of cause

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4
Q

AKI:

Etiologies can be

1.

2.

3.

A

AKI:

Etiologies can be Pre - renal, intrarenal, or post renal

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5
Q

Pre-Renal Causes of AKI:

Absolute decrease in effective circulatory volume:

Relative decrease in effective circulatory volume:

Impaired renal autoregulation with low ECV:

Renal Vasoconstriction or Occlusion

A

PreRenal Causes of AKI

Absolute decrease in ECV: hemmorhage or volume depletion

Relative decrease in EVC: heart failure, cirrhosis

Impaired renal autoregulation with low ECV: NSAIDS, ACEI/ARBs

Renal vasoconstriction or occlusion: renal artery stenosis, hypercalcemia

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6
Q

Urine in Pre-renal State of AKI:

Since kidneys per se are fine with intact tubules, ____ is retained in an attempt to conserve volume

Urine is ____ with _____

A

Urine in pre-renal state of AKI:

Kidneys are per se fine, Na/H20 will be retained to conserve volume

Urine is bland with no WBCs or RBCs

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7
Q

Urine Indices in Pre-Renal State of AKI:

Urine will be _______ in an effort to conserve volume and sodium as much as possible

What happens to serum bun/cr ratio?

A

Urine Indices in Pre-Renal State of AKI:

Urine will be concentrated in an effort to conserve volume and sodium as much as possible (>500)

Urea gets reabsorbed with sodium and water, so BUN:creatinine ratio is HIGHER (20:1)

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8
Q

Acute Tubular Necrosis:

What is it?

Explain the different causes

Then give examples of what will cause each category

A

Acute Tubular Necrosis:;

Injury to renal tubules leading to AKI

Most common cause of AKI in hospitalized patients

ATN can be due to toxic causes or ischemia

Toxic:

  • exogenous (antibiotics like vancomyocin, antifungals like amphotericin, chemo agents, contrast, mannitol)
  • endogenous: myoglobin (rhabdo), uric acid, hemoglobin, bilirubin (liver failure)

Ischemia:

  • prolonged prerenal state
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9
Q

Acute Tubular Necrosis:

______ and _____ are highly suceptible to ischemic injury

________ are susceptible to toxic injury

A

Acute Tubular Necrosis (ATN):

Proximal convoluted tubule and thick ascending limb are prone to ischemia

Proximal tubules are most susceptible to toxic injury

Tubular segments that have high o2 requirement from high metabolic rate are thought to be most suceptible to injury

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10
Q

Acute tubular necrosis: Clinical Course:

Initiation Phase (hours to days): _____ tubular injury, potentially reversible if diagnosed early

Maintanence Phase: (1-3 weeks)

  • may be prolonged to 3 months
  • ______ renal injury
  • generally _____uric during this phase
  • ______ urine with ____

Recovery Phase:

  • repair and regeneration of tubules
  • recovery of renal function with decreasing BUN and creatinine
  • ____uric phase and at risk for ____ K and ___ Na due to impaired reabsorption
A
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11
Q

Urine Analysis in Intrinsic Kidney Injury
Urine is ______

Urine Na is ______

Serum BUN/Cr is _____

What does this reflect?

A

Urine Analysis in Intrinsic Kidney Injury

Urine is abnormal (kidneys screaming for your attention)

Urine Na is high… > 40 (tubules are injured, impaired reabsorption of sodium)

Serum BUN/Cr ratio is low (<10:1)

This reflects impaired tubular function

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12
Q

Urinary Casts:

They are _____ in shape

They are aggregations of _______

Urinary casts are formed under what conditions?

Thus urinary casts are indicative of ___ GFR?

A

Urinary Casts:

They are cylindrical

These are aggregations of glycoproteins

Urinary casts are formed under LOW flow, acidic conditions

Urinary casts are indicative of low GFR (can also be seen in glomerular diseases)

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13
Q

Rhabdomyolysis:

Common cause of AKI in _____

Breakdown of _____

Urine characteristics?

A

Rhabdomyolysis:

Common cause of AKI in males (athletes, those training in HIIT or crush injury)
Breakdown of muscle tissue (aka myo..lysis)

Urine characteristics: reddish brown urine due to myoblobin

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14
Q

Rhabdomyolysis causing renal failure:

Rupture of skeletal muscle causes contents to be released into blood stream

Cause of renal failure is typically ____ forming a ___

Causing ______ GFR due to clogging the ____

A

Rhabdomyolysis causing renal failure:

Rupture of skeletal muscle causes contents to be released into blood stream

Cause of renal failure is typically myoglibin forming a proteinaceous gel…. causing decreased GFR

That myoglobin gell gets clogged in the loop of Henle (u-bend in kitchen sink)

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15
Q

“Bloody Urine in Rhabdomyolisis:

What is the reddish brown color in rhabdo caused by?

A

Rhabdomyolysis

Brown-reddish urine is due to MYOGLOBIN

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16
Q

Complications and treatment of Rhabdomyolysis:

If left untreated, rhabdo can cause ____ and ___

What is the treatment for rhabdo?

A

If left untreated, rhabdomyolysis can cause:

  • high plasma K/hyperkelemia (due to muscle lysis and impaired urine excretion)
  • metabolic acidosis

Treatment: controlled IV fluids…. flush out kidneys like you flush out your kitchen sink

17
Q

Post Renal/ Obstructive Uropathy:

Structural or functional hindrance to urinary flow leading to ____ and ____

Can be ___ or ____ obstruction

A

Post Renal/Obstructive Uropathy:
Structural or Functional Hindrance to urinary flow leading to back up of urine and decrease in GFR

Can be upper urinary tract obstruction (ureters) or lower urinary tract obstruction (bladder and below)

18
Q

Upper Urinary Tract Obstruction (ureters involved):

Renal failure seen in _____ or _______

Common causes?

How to dianose?

A

Upper Urinary Tract Obstruction (ureters involved):

Renal failure seen in bilateral obstruction or single functioning kidney or unilateral obstruction with baseline CKD

Common cause: bilateral kidney stones, extrinsic compression by tumors/fibrosis

Diagnosis: Ultrasound or CT (hydronephrosis, aka watery urine back up into kidney)

19
Q

Lower Urinary tract obstruction:
Common causes?

Clinical findings?

Diagnosis?

A

Lower Urinary Tract Obstruction:

Common causes: BPH, drugs, neurogenic bladder

Clinical Findings: fullness of bladder on palpation

Diagnosis: post void residual, or ultrasound with distended bladder