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D&T test 5 - Renal, Urogential > Pathoma12.2 Acute Renal Failure (ARF) > Flashcards

Pathoma12.2 Acute Renal Failure (ARF) Flashcards

1
Q

What are the 2 hallmarks of acute renal failure (ARF)?

A

Azotemia

oliguria

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2
Q

What is azotemia

A

increased BUN and Creatinine (Cr)

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3
Q

What causes prerenal azotemia

A

decreased BF to kidneys

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4
Q

what is a normal BUN:Cr ratio?

A

15

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5
Q

when the tubule is intact, what is the fractional excretion of Sodium [FENa] and urine osmolality [osm]

A

FENa <1%

[osm] > 500mOsm/kg

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6
Q

What happens to BUN:Cr ratio in prerenal azotemia?

A

it increases >15

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7
Q

What is Mechnism of BUN:Cr increase in prerenal azotemia?

A

decreased GFR –> decreased Na–> renin–> Aldo–> Na and water reabsorbed–> BUN reabsorbed–> increased BUN:Cr ratio

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8
Q

what happens to FENa and urine osm in prerenal azotemia and why

A

nothing

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9
Q

what happens to FENa and urine osm in early stages of postrenal azotemia and why

A

nothing= normal

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10
Q

what happens to FENa and urine osm in late stage postrenal azotemia and why

A

FENa increases (>2%) because tubule can’t reabsorb sodium and [osm] decreases (<500) bc can’t concentrate urine

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11
Q

what is cause of Postrenal azotemia (MOA)

A

obstruction of urinary tract (ureter) downstream from kidney–> decreased outflow–> decreased GFR (backpressure), azotemia, oliguria

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12
Q

BUN:Cr in early postrenal azotemia and why?

A

> 15 because increased tubular pressure forces BUN into blood

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13
Q

BUN:Cr in late postrenal azotemia and why?

A

<15 because tubular damage makes reabsorbing BUN impossible–> decreased BUN:Cr

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14
Q

What are the 2 forms of intrarenal azotemia?

A

Acute tubular necrosis

Acute interstitial nephritis

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15
Q

What happens to GFR in Acute tubular necrosis and why

A

decreases becuase necrotic tubular cells plug the tubule

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16
Q

What is seen in the urine in Acute tubular necrosis

A

brown, granular casts (made of necrotic tubular cells)

17
Q

What happens to BUN:Cr in Acute tubular necrosis

A

decreased

18
Q

What does BUN reabsorption depend on ***

A

normal/intact tubular cells

19
Q

What happens to FENa and urine osm in Acute tubular necrosis

A 
FENa increases (>2%) because can't reabsorb sodium
[osm] decreases (<500) because can't concentrate urine
20
Q

2 etiologies of Acute Tubular necrosis

A

Ischemia

Nephrotoxic

21
Q

Ischemic Acute Tubular necrosis affects what parts of the tubule?

A

PCT, medullary segment of TAL

22
Q

Nepphrotoxic Acute Tubular necrosis affects what parts of the tubule?

A

PCT

23
Q

6 common causes of Nephrotoxic Acute Tubular necrosis

A
  1. Aminoglycosides
  2. Urate (tumor lysis syndrome)
  3. Lead
  4. Myoglobinuria (crush injury)
  5. ethylene glycol (oxalate crystals in urine)
  6. radiocontrast dye
24
Q

What is tumor lysis syndrom eand why does it cause nephrotoxic Acute Tubular necrosis?

A

chemothx kills large amounts of cells which leads to release of nuclear contents including uric acid–>tubular damage

25
Q

What 2 things are used to prevent urate-induced Acute Tubular necrosis

A

Hydration (increased GFR)

Allopurinol

26
Q

what electrolytes are changed in ATN?

A

hyperkalemia

metabolic acidosis

27
Q

WHat happens to BUN and Cr levels in ATN and why?

A

both increase due to decreased GFR

28
Q

What happens to urine output in ATN?

A

it decreases

29
Q

Prognosis of ATN

A

reversible but requires dialysis

30
Q

how long does oliguria persist in ATN and why?

A

2-3 weeks because tubular cells are STABLE and take time to reenter the cell cycle and regenerate

31
Q

What is the cuase of Acute Interstitial Nephritis (AIN)?

A

drug-induced HSR

32
Q

3 drug types that cause AIN

A

penicillin, diuretics, NSAIDs

33
Q

how does AIN present? 4 things?

A

oliguria, rash, fever, eosinophils in urine

34
Q

What does AIN progress to?

A

Renal Papillary Necrosis

35
Q

How does Renal Papillary Necrosis present (2)

A

gross hematuria, flank pain

36
Q

4 causes of Renal Papillary Necrosis

A
  1. Chronic analgesic abuse (phenacetin or aspirin)
  2. Diabetes Mellitus
  3. Sickle cell trait or disease
  4. Acute pyelonephritis

D&T test 5 - Renal, Urogential (27 decks)

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